Buspirone
Buspirone is an oral anxiolytic (azapirone class) used for the management of anxiety disorders or short-term relief of the symptoms of anxiety. Buspirone is used for Anxiety disorders / symptoms of anxiety and Depression.
Also called: Bucapsol (United States)
Pronunciation: pronunciation varies by local usage.
- Generic name
- buspirone hydrochloride
- Drug class
- Anxiolytic (azapirone; non-benzodiazepine)
- Form
- Tablet (US labelling: buspirone hydrochloride tablets, USP; UK labelling: buspirone hydrochloride 10 mg tablets). The notes do not describe other dosage forms.
- Route
- Oral
- Legal status
- Prescription-only medicine; not a controlled substance
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What buspirone hydrochloride is and how it works
Buspirone is an oral anxiolytic (azapirone class) used for the management of anxiety disorders or short-term relief of the symptoms of anxiety. In the US label, efficacy was shown in outpatients whose diagnosis roughly corresponds to generalized anxiety disorder, including patients with coexisting depressive symptoms. The UK SmPC wording covers the short-term management of anxiety disorders and relief of symptoms of anxiety with or without accompanying depression. Its mechanism of action is not known; it has high affinity for 5-HT1A receptors and moderate affinity for D2 receptors, with no significant affinity for benzodiazepine receptors. (1) (3) (5)
US and UK labelling differ in several areas, including doses, contraindications, and how severe kidney or liver problems are handled; the relevant local label applies. Buspirone is not a controlled substance and human and animal studies show no evidence of abuse potential, tolerance, or physical or psychological dependence. The sources retrieved do not state how quickly buspirone starts to work.
Mechanism of action: how buspirone hydrochloride works
The mechanism of buspirone's anxiolytic action is unknown. Unlike benzodiazepines it has no anticonvulsant or muscle-relaxant effect and lacks prominent sedation. It has high affinity for 5-HT1A receptors and moderate affinity for D2 receptors, with no significant affinity for benzodiazepine receptors. Buspirone is about 95% plasma protein bound. In vitro it does not displace tightly bound drugs such as warfarin from serum proteins but may displace less firmly bound drugs such as digoxin, with unknown clinical significance. (1) (5)
What is Buspirone hydrochloride used for?
Anxiety disorders / symptoms of anxiety
Buspirone is indicated for the management of anxiety disorders or short-term relief of the symptoms of anxiety. In the US label, efficacy was shown in outpatients whose diagnosis roughly corresponds to generalized anxiety disorder, including patients with coexisting depressive symptoms. The US label notes that anxiety or tension associated with everyday stress usually does not require an anxiolytic. The UK SmPC describes short-term management of anxiety disorders and relief of anxiety symptoms with or without accompanying depression. (1) (5)
Limits of the evidence
The US label states that effectiveness in long-term use, that is, for more than 3 to 4 weeks, has not been demonstrated in controlled trials. The UK SmPC describes use as short-term. The sources retrieved do not state a time to onset of anxiolytic effect. (1) (5)
Depression
The UK SmPC states that buspirone should not be used alone to treat depression and may potentially mask the clinical signs of depression. Depression with anxiety should be assessed and managed by a clinician. (5)
Before taking buspirone hydrochloride
Do not take / not appropriate for
- Do not use buspirone if you have had a hypersensitivity reaction to buspirone hydrochloride or to any ingredient of the tablet. This is a listed contraindication in both the US and UK labelling. (all products) (1) (5)
- Do not use buspirone together with an MAOI intended to treat depression, or within 14 days of stopping either drug. The US label lists this as a contraindication because of serotonin syndrome and/or elevated blood pressure; the UK SmPC states that buspirone is not recommended with an MAOI and that elevated blood pressure has been reported when buspirone is added to an MAOI regimen. (all products) (1) (5)
- Do not start buspirone in a patient already being treated with a reversible MAOI such as linezolid or intravenous methylene blue. Listed as a contraindication in the US label. (US labelling) (1)
- Severe liver or kidney impairment — the US label says use in patients with severe hepatic or renal impairment cannot be recommended. This is a 'not recommended' statement in US labelling, not a formal contraindication there. UK labelling instead lists severe renal or hepatic impairment as a contraindication (severe renal impairment defined in UK labelling as creatinine clearance 20 ml/min or below, or plasma creatinine above 200 micromol/l). Seek clinician advice rather than adjusting anything yourself. (label-dependent; see text) (1) (5)
- In the UK, buspirone is contraindicated in epilepsy and in acute intoxication with alcohol, hypnotics, analgesics, or antipsychotic drugs. Decision on suitability rests with the prescriber under the applicable label. (UK labelling) (5)
Tell your clinician about
- All medicines you take, especially antidepressants including MAOIs, SSRIs, fluvoxamine, nefazodone, trazodone, tricyclics, lithium, tramadol, triptans, linezolid, and St John's wort, and antipsychotics or dopamine antagonists.
- Medicines that affect CYP3A4, including erythromycin, itraconazole, diltiazem, verapamil, rifampicin, phenobarbital, phenytoin, carbamazepine, cimetidine, and grapefruit juice.
- Alcohol use, and sedating medicines such as baclofen, lofexidine, nabilone, or antihistamines.
- Kidney or liver problems, including any previous diagnosis or history of hepatic or renal impairment.
- In the UK: a history of epilepsy or acute intoxication with alcohol, hypnotics, analgesics, or antipsychotics, and rare hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption (the UK SmPC says such patients should not take this medicine).
- Narrow-angle glaucoma, myasthenia gravis, or a history of drug dependence, which the UK SmPC lists as situations requiring care.
- Pregnancy, plans for pregnancy, breastfeeding, and the use of any other medicine, including warfarin, haloperidol, diazepam, or digoxin.
- Whether you drive or operate machinery, because buspirone has a moderate influence on the ability to drive and use machines.
- Whether you are taking benzodiazepines or other sedative/hypnotic drugs: buspirone does not share cross-tolerance with them and will not prevent their withdrawal syndrome, so the prescriber should plan any withdrawal.
Buspirone hydrochloride dosage and how to take it
- Take buspirone exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. All dose figures below are prescriber-directed label information, not instructions to follow on your own.
- US label adult dose: recommended initial dose 15 mg daily given as 7.5 mg twice daily; it may be increased by 5 mg per day at intervals of 2 to 3 days as needed; maximum 60 mg per day. In trials, divided doses of 20 mg to 30 mg per day were commonly used.
- UK SmPC adult dose (including the elderly): usual starting dose 5 mg two to three times per day; the dose may be increased every 2 to 3 days; usual therapeutic dose 15 to 30 mg daily in divided doses; maximum recommended dose 45 mg daily in divided doses.
- Take it at the same time each day and consistently either always with food or always without food, because food increases the bioavailability of buspirone.
- The prescriber may start you on a low dose and gradually increase it, not more often than once every 2 to 3 days. It may take several weeks before you reach a dose that works for you. The sources retrieved do not state a time to onset of anxiolytic effect.
- Dose changes are made by the prescriber only; do not self-adjust the dose.
- If buspirone is taken with a potent CYP3A4 inhibitor, the label's lower-dose interaction guidance applies and is a prescriber decision.
- Avoid consuming large quantities of grapefruit juice while taking buspirone.
- The UK SmPC advises that alcohol use should be avoided, and that patients should be gradually withdrawn from benzodiazepines or other sedative/hypnotic drugs before buspirone is started; that withdrawal plan is the prescriber's decision.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (3) (5)
Missed dose
Take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue the regular schedule. Do not take a double dose. Contact the prescriber or pharmacist if you are unsure.
Overdose
In normal volunteers the maximum tolerated dose of buspirone was 375 mg/day; as maximum dose levels were approached the most commonly observed symptoms included nausea, vomiting, headache, dizziness, drowsiness, tinnitus, restlessness, miosis, and gastric distress. Mild bradycardia and hypotension have been reported, extrapyramidal symptoms have been reported after therapeutic doses, and convulsions may rarely occur. No deaths have been reported with buspirone alone; rare fatal intentional overdoses always involved multiple drugs and/or alcohol. There is no specific antidote and buspirone is not removed by haemodialysis. Treatment is symptomatic and supportive with monitoring of breathing, pulse and blood pressure, and the stomach should be emptied as quickly as possible. Call emergency services or a poison control centre (US 1-800-222-1222) immediately, and tell the treating team about any other medicines or alcohol involved. (1) (5)
Buspirone hydrochloride side effects
Side effects of buspirone, if they occur, are generally observed at the beginning of drug therapy and usually subside with continued use and/or a decreased dosage. Dizziness, headache, nervousness, lightheadedness, nausea, excitement, and sweating/clamminess were the side effects occurring with significantly greater frequency than placebo. In premarketing trials, about 10% of 2,200 patients discontinued for an adverse event, mainly CNS effects such as dizziness, insomnia, nervousness and drowsiness; nausea; and headache and fatigue. Frequency categories below follow the UK SmPC (very common at least 1 in 10; common at least 1 in 100 and less than 1 in 10; very rare less than 1 in 10,000) — read them as label information, not as a personal prediction.
Dizziness (including lightheadedness), headache, somnolence
What to notice: These are listed as very common in the UK SmPC. Dizziness and lightheadedness are also among the events reported more often than placebo.
What to do: Discuss persistent or troublesome symptoms with the prescribing team rather than changing the dose yourself. (5) (1)
Nervousness, insomnia, disturbance in attention, depression, confusional state, sleep disorder, anger
What to notice: Listed as common psychiatric adverse events in the UK SmPC.
What to do: Tell the prescribing team, especially if mood symptoms are new or worsening. (5)
Paraesthesia, blurred vision, abnormal coordination, tremor, tinnitus
What to notice: Listed as common nervous system adverse events in the UK SmPC.
What to do: Report persistent or worsening symptoms to the prescribing team. (5)
Tachycardia, chest pain
What to notice: Listed as common cardiac adverse events in the UK SmPC.
What to do: New or persistent chest pain or a racing heartbeat should be assessed promptly by a clinician. (5)
Nasal congestion, pharyngolaryngeal pain
What to notice: Listed as common respiratory adverse events in the UK SmPC.
What to do: Tell the prescribing team if troublesome or persistent. (5)
Nausea, abdominal pain, dry mouth, diarrhoea, constipation, vomiting
What to notice: Listed as common gastrointestinal adverse events in the UK SmPC; nausea is also among events reported more often than placebo.
What to do: Discuss persistent symptoms with the prescribing team rather than changing the dose yourself. (5) (1)
Cold sweat, rash
What to notice: Listed as common skin and subcutaneous tissue adverse events in the UK SmPC; sweating/clamminess is among events reported more often than placebo.
What to do: Tell the prescribing team; seek prompt assessment for any swelling of the face, lips or throat or widespread rash. (5) (1)
Musculoskeletal pain; fatigue
What to notice: Listed as common in the UK SmPC.
What to do: Discuss persistent or troublesome symptoms with the prescribing team. (5)
Suspected serotonin syndrome
What to notice: Mental status changes (agitation, hallucinations, delirium, coma); autonomic instability (fast heart rate, labile blood pressure, dizziness, sweating, flushing, high temperature); neuromuscular changes (tremor, rigidity, muscle jerks/myoclonus, overactive reflexes, incoordination); seizures; and/or nausea, vomiting, diarrhoea.
What to do: Get urgent medical help if these appear. The UK SmPC advises that if serotonin syndrome is suspected, treatment with buspirone should be immediately discontinued and supportive symptomatic treatment initiated — let the clinician you see advise on whether to continue or stop buspirone. Patients on other serotonergic medicines should be monitored. (1) (5)
Elevated blood pressure when combined with an MAOI
What to notice: Elevated blood pressure reported when buspirone is added to an MAOI regimen.
What to do: Seek prompt medical assessment. Buspirone is not recommended with an MAOI, and the US label lists combined use within 14 days of stopping either drug as a contraindication. (1) (5)
Seizures
What to notice: Convulsions. Rare cases of seizures have been reported in patients taking buspirone with SSRIs, and convulsion is listed as a very rare adverse event; rare seizures may also occur in overdose.
What to do: Seek emergency medical attention. (5)
Other very rare effects listed in the UK SmPC
What to notice: Psychotic disorder, hallucination, depersonalization, affect lability, tunnel vision, extrapyramidal disorder, cogwheel rigidity, dyskinesia, dystonia, syncope, amnesia, ataxias, Parkinsonism, akathisia, restless leg syndrome, restlessness, urinary retention, galactorrhoea, angioneurotic oedema, ecchymosis, urticaria.
What to do: Report these to the prescribing team or seek medical assessment promptly; do not change or stop treatment yourself. (5)
Possible effects on other medicines
What to notice: Increases in prothrombin time have been reported after buspirone was added to a warfarin regimen, and haloperidol serum levels can increase when haloperidol and buspirone are taken together.
What to do: Tell the prescriber and any anticoagulation or monitoring service about all medicines so monitoring can be arranged. (5)
Transaminase increase with trazodone
What to notice: Concomitant administration of trazodone showed a 3-6 fold increase of ALT in some patients.
What to do: The prescribing team decides on any liver monitoring; report symptoms such as yellowing of the skin or eyes. (5)
Serious warnings
Serotonin syndrome — urgent
Symptoms: Mental status changes (agitation, hallucinations, delirium, coma); autonomic instability (fast heart rate, labile blood pressure, dizziness, sweating, flushing, high temperature); neuromuscular changes (tremor, rigidity, muscle jerks/myoclonus, overactive reflexes, incoordination); seizures; and/or nausea, vomiting, diarrhoea.
Action: Get urgent medical help. Serotonin syndrome has been reported with buspirone, particularly with other serotonergic drugs (including triptans), drugs impairing serotonin metabolism, or antipsychotics/dopamine antagonists, and in isolated reports in patients on concomitant SSRI therapy. Patients should be monitored. In the UK SmPC, suspected serotonin syndrome means buspirone should be immediately discontinued and supportive symptomatic treatment initiated — the clinician you see advises on whether to continue or stop buspirone. (1) (5)
MAOI combination — urgent
Symptoms: Elevated blood pressure; the US label also cites serotonin syndrome as a reason for the contraindication.
Action: Buspirone must not be used with MAOIs intended to treat depression or within 14 days of stopping either drug (US contraindication). Seek urgent medical assessment if you have taken both. The UK SmPC states that buspirone is not recommended with an MAOI and that elevated blood pressure has been reported when buspirone is added to an MAOI regimen. (1) (5)
Severe hepatic or renal impairment — label-dependent
Symptoms: Steady-state AUC rose 13-fold in hepatic impairment; the US label says use in patients with severe hepatic or renal impairment cannot be recommended, and the UK SmPC lists severe renal or hepatic impairment as a contraindication (UK severe renal impairment: creatinine clearance 20 ml/min or below, or plasma creatinine above 200 micromol/l). UK labelling also states buspirone should not be administered to patients with a creatinine clearance below 20 ml/min/1.72 m2, especially anuretic patients, because of possible increased and untreated levels of buspirone and its metabolites. In mild to moderate renal insufficiency (creatinine clearance 20-49 ml/min/1.72 m2) a slight increase in buspirone blood levels was seen without an increase in half-life, and UK labelling advises caution with a low dosage twice daily and careful evaluation before any increase. In cirrhosis, higher maximum concentrations of unchanged buspirone and an increased half-life occur, and UK labelling advises caution with careful individual titration and consideration of increased doses only after 4-5 days' experience with the prior dosage.
Action: Tell your prescriber about any kidney or liver problem so the applicable label can be applied. Do not change your dose yourself. (1) (5)
Driving and operating machinery — caution
Symptoms: Buspirone has a moderate influence on the ability to drive and use machines; drowsiness or dizziness induced by the drug are the relevant risks, and the medicine can impair cognitive function.
Action: UK SmPC advice to patients: the medicine is likely to affect your ability to drive; do not drive until you know how the medicine affects you; it is an offence to drive while under the influence of this medicine. Discuss driving with your prescriber. (5)
Depression — caution
Symptoms: Buspirone should not be used alone to treat depression and may potentially mask the clinical signs of depression.
Action: Tell your prescriber about depression or any change in mood so it can be assessed and managed appropriately. (5)
Benzodiazepine and sedative/hypnotic withdrawal — caution
Symptoms: Buspirone does not exhibit cross-tolerance with benzodiazepines and other common sedative/hypnotic agents and will not block the withdrawal syndrome often seen with cessation of therapy with these agents.
Action: UK labelling advises that patients should be gradually withdrawn from these agents before buspirone treatment is initiated, especially patients who have used a CNS-depressant drug chronically; the withdrawal plan is the prescriber's decision. Do not stop any sedative or hypnotic yourself. (5)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| MAO inhibitors | Co-administration may cause increases in blood pressure; the US label lists combined use, or use within 14 days of stopping either drug, as a contraindication because of serotonin syndrome and/or elevated blood pressure. Elevated blood pressure has been reported when buspirone was added to regimens including phenelzine and tranylcypromine. | Buspirone is not recommended with an MAOI; tell the prescriber and pharmacist about every antidepressant you take, and seek urgent advice if both have been taken. (1) (5) |
| Grapefruit juice | In healthy volunteers, buspirone 10 mg with double-strength grapefruit juice (200 mL for 2 days) increased buspirone plasma concentrations (Cmax increased 4.3-fold and AUC 9.2-fold); the US label reports a 9.2-fold AUC increase with 200 mL double-strength three times daily. | Patients taking buspirone should avoid consuming large quantities of grapefruit juice. (1) (5) |
| Erythromycin | Concomitant buspirone 10 mg single dose and erythromycin 1.5 g once daily for four days increased buspirone plasma concentrations (Cmax 5-fold, AUC 6-fold), with more side effects. | If used in combination, UK labelling recommends a low buspirone dose (e.g. 2.5 mg twice daily), with subsequent adjustments of either drug based on clinical response; this is a prescriber decision. (1) (5) |
| Itraconazole | Concomitant buspirone 10 mg single dose and itraconazole 200 mg once daily for four days increased buspirone plasma concentrations (Cmax 13-fold, AUC 19-fold), with more side effects. | If used in combination, UK labelling recommends a low buspirone dose (e.g. 2.5 mg once daily), with subsequent adjustments based on clinical response; this is a prescriber decision. (1) (5) |
| Potent CYP3A4 inhibitors (general) | When administered with a potent inhibitor of CYP3A4, buspirone exposure increases. | UK labelling recommends a low dose of buspirone used cautiously; if buspirone is given with a potent CYP3A4 inhibitor the initial dose should be lowered and only increased gradually after medical evaluation. US labelling directs following the label's lower-dose interaction guidance. Prescriber decision. (1) (5) |
| Diltiazem | Concomitant buspirone 10 mg single dose and diltiazem 60 mg three times daily increased buspirone plasma concentrations (Cmax 5.3-fold, AUC 4-fold); enhanced effects and increased toxicity of buspirone may be possible. | Subsequent dose adjustments of either drug should be based on clinical response; discuss with the prescriber. (5) |
| Verapamil | Concomitant buspirone 10 mg single dose and verapamil 80 mg three times daily increased buspirone Cmax and AUC 3.4-fold; enhanced effects and increased toxicity of buspirone may be possible. | Subsequent dose adjustments of either drug should be based on clinical response; discuss with the prescriber. (5) |
| Rifampicin and other CYP3A4 inducers | Rifampicin induces buspirone metabolism via CYP3A4; buspirone 30 mg single dose with rifampicin 600 mg once daily for 5 days decreased buspirone Cmax by 84% and AUC by 90%, and reduced its pharmacodynamic effect. The US label reports rifampin reduced AUC by 89.6%. Potent inducers include phenobarbital, phenytoin, carbamazepine and St John's wort. | An adjustment of the buspirone dose may be necessary to maintain its anxiolytic effect; this is a prescriber decision. (1) (5) |
| Nefazodone | Co-administration of buspirone (2.5 or 5 mg twice daily) and nefazodone (250 mg twice daily) in healthy volunteers markedly increased plasma buspirone concentrations (up to 20-fold in Cmax and up to 50-fold in AUC) with about a 50% decrease in the metabolite 1-pyrimidinylpiperazine. Subjects on buspirone 5 mg twice daily with nefazodone experienced lightheadedness, asthenia, dizziness and somnolence. | It is recommended that the dose of buspirone be lowered when administered with nefazodone, with subsequent adjustments based on clinical response; prescriber decision. (5) |
| Fluvoxamine | In short-term treatment with fluvoxamine and buspirone, doubled buspirone plasma concentrations were observed compared with buspirone alone. | Tell the prescriber about any SSRI so that dose decisions are made in the light of the interaction. (5) |
| Trazodone | Concomitant administration of trazodone showed a 3-6 fold increase of ALT in some patients. | Discuss with the prescriber, who may arrange monitoring. (5) |
| SSRIs and other serotonergic drugs (including L-tryptophan, triptans, tramadol, linezolid, lithium and St John's wort) | Although no severe toxicities were observed in trials testing buspirone with SSRIs, there were rare cases of seizures and isolated reports of serotonin syndrome; separate cases of seizures with buspirone plus SSRIs have been reported in regular clinical use. | Buspirone should be used with caution with serotonergic drugs; report symptoms of serotonin syndrome urgently, and let the clinician you see advise on whether to continue or stop buspirone. (5) |
| Other CNS-active drugs, and sedative-enhancing medicines (baclofen, lofexidine, nabilone, antihistamines) | Concomitant use of buspirone with other CNS-active drugs should be approached with caution; baclofen, lofexidine, nabilone and antihistamines may enhance any sedative effect. | Give the prescriber and pharmacist a full medicine list before starting buspirone. (5) |
| Cimetidine | Concomitant use of buspirone and cimetidine has shown a slight increase in the 1-(2-pyrimidinyl)-piperazine metabolite of buspirone; buspirone is about 95% protein bound, so caution is advised when drugs with high protein binding are given together. | Tell the prescriber about cimetidine and any highly protein-bound medicines. (5) |
| Warfarin and other protein-bound drugs | There are reports of increases in prothrombin time after the addition of buspirone to a treatment regimen containing warfarin. In vitro, buspirone does not displace warfarin, digoxin, phenytoin or propranolol from plasma proteins, while it may displace less firmly protein-bound drugs like digoxin; the clinical significance of this is unknown. | Tell the prescriber and any anticoagulation service about buspirone so monitoring can be arranged. (5) |
| Haloperidol | Concomitant administration of haloperidol and buspirone can increase haloperidol serum levels. | Tell the prescriber if both are used. (5) |
| Diazepam | After addition of buspirone to a diazepam regimen, no statistically significant differences in steady-state pharmacokinetic parameters (Cmax, AUC, Cmin) were observed for diazepam, but increases of about 15% were seen for nordiazepam, and minor adverse clinical effects (dizziness, headache, nausea) were observed. | Report dizziness, headache or nausea to the prescriber. (5) |
| Amitriptyline | In healthy volunteers no interaction with the tricyclic antidepressant amitriptyline was seen. | Still tell the prescriber about all antidepressants being taken. (5) |
| Alcohol | Alcohol use should be avoided, although buspirone has not been reported to potentiate the psychomotor impairment produced by alcohol; no data are available on concomitant use of alcohol and single doses of buspirone greater than 20 mg. | Avoid alcohol and discuss any alcohol use with the prescriber. (5) |
Special populations
Children and adolescents (under 18 years)
Placebo-controlled trials in which 334 patients were treated with buspirone for up to six weeks have not shown buspirone at doses recommended for adults to be an effective treatment for generalised anxiety disorder in patients less than 18 years. Plasma concentrations of buspirone and its active metabolite were higher in paediatric patients than in adults given equivalent doses. The long-term safety and effectiveness of buspirone have not been determined in individuals below 18 years of age, and the UK SmPC states buspirone is not recommended in children and adolescents. (5)
Older people
The UK SmPC gives the same usual starting dose of 5 mg two to three times per day for adults including the elderly, with individualised dosing. The notes retrieved contain no separate older-person US dose figure. (5)
Pregnancy
There are no adequate well-controlled human pregnancy studies; US labelling says use during pregnancy only if clearly needed. The UK SmPC states there are no or limited data from use in pregnant women, that animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity, and that as a precautionary measure it is preferable to avoid the use of buspirone during pregnancy. The effect of buspirone on labour and delivery is unknown. Do not change treatment yourself; discuss pregnancy and treatment with the prescriber. The sources used here give no FDA pregnancy-letter category, and none should be presented. (1) (5)
Breastfeeding
It is unknown whether buspirone or its metabolite(s) are excreted in human milk; buspirone is excreted in rat milk. US labelling says administration to nursing women should be avoided if clinically possible. The UK SmPC states a decision must be made whether to discontinue breast-feeding or to discontinue/abstain from buspirone therapy, taking into account the benefit of breast feeding for the child and the benefit of therapy for the woman. Discuss this with the prescriber rather than deciding alone. (1) (5)
Severe hepatic or renal impairment
US labelling states use in patients with severe hepatic or renal impairment cannot be recommended. UK labelling lists severe renal or hepatic impairment as a contraindication and gives specifics (see serious warnings). Steady-state AUC rose 13-fold in hepatic impairment. The prescriber applies the applicable local label. (1) (5)
Mild to moderate renal insufficiency and anuric patients
UK labelling describes a slight increase in buspirone blood levels without increased half-life in mild to moderate renal insufficiency, with careful evaluation before any dose increase and a low twice-daily dosage advised; buspirone should not be administered to patients with a creatinine clearance below 20 ml/min/1.72 m2, especially anuretic patients. A single administration in anuretic patients increased levels of the metabolite 1-pyrimidine/piperazine (1-PP), and dialysis did not influence buspirone or 1-PP levels. (5)
Epilepsy, glaucoma, myasthenia gravis and drug dependence
UK labelling contraindicates buspirone in patients with epilepsy and lists acute narrow-angle glaucoma, myasthenia gravis and drug dependence as situations requiring care. Tell the prescriber about any of these. (5)
Hereditary galactose intolerance, lactase deficiency or glucose-galactose malabsorption
UK labelling states that patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine. (5)
Long-term use
The US label states that effectiveness in long-term use, that is, for more than 3 to 4 weeks, has not been demonstrated in controlled trials. The UK SmPC also describes short-term management. The sources retrieved do not state a time to onset of effect. (1) (5)
Monitoring
Before starting
- Confirm the exact diagnosis and whether an anxiolytic is appropriate; the US label notes that anxiety or tension associated with everyday stress usually does not require an anxiolytic.
- Check for hypersensitivity to buspirone or tablet ingredients, current or recent MAOI use (including within 14 days of stopping either drug), and treatment with reversible MAOIs such as linezolid or IV methylene blue.
- Check for severe hepatic or renal impairment, and for UK labelling also epilepsy, acute intoxication with alcohol, hypnotics, analgesics or antipsychotics, narrow-angle glaucoma, myasthenia gravis, drug dependence, and hereditary galactose intolerance or lactase deficiency.
- Review all medicines for CYP3A4 inhibitors and inducers, serotonergic drugs, CNS-active drugs, sedating medicines, and protein-bound drugs such as warfarin and digoxin.
- Ask about grapefruit juice intake and alcohol use.
- Review pregnancy status, breastfeeding, and plans for either.
- Discuss driving and operating machinery, since buspirone has a moderate influence on these and can impair cognitive function.
During treatment
- Monitor for serotonin syndrome, particularly when buspirone is used with other serotonergic drugs (including triptans), drugs impairing serotonin metabolism, or antipsychotics/dopamine antagonists, and in patients on concomitant SSRI therapy.
- Monitor for elevated blood pressure where an MAOI has been involved.
- Reassess the dose slowly, following the applicable label; the prescriber increases the dose gradually (not more often than once every 2 to 3 days in the MedlinePlus wording), and reaching an effective dose may take several weeks.
- Reassess adverse effects and continue to be alert to effects that are rare, including convulsion, extrapyramidal symptoms, urinary retention and galactorrhoea.
- For patients with hepatic or renal impairment, titrate with care according to the applicable label, and consider increased doses only after 4-5 days' experience with the prior dosage in cirrhosis (UK labelling).
- Watch for possible effects on other medicines, such as prothrombin-time increases with warfarin and increased haloperidol levels, and arrange monitoring accordingly.
- The sources retrieved do not state a time to onset of anxiolytic effect; do not infer one from this page.
Storage
Store at 20-25 degrees C (68-77 degrees F) according to the label. MedlinePlus consumer advice: keep in the original container, tightly closed, out of reach of children, at room temperature away from light, excess heat and moisture (not in the bathroom).
Professional information
Clinician-facing context only. Use the current local indication, dosing instructions, contraindications, interaction guidance and monitoring requirements; US and UK labelling differ materially for buspirone.
United States
Indication: Anxiety disorders / symptoms of anxiety
Dose summary: Recommended initial dose 15 mg daily given as 7.5 mg twice daily; may be increased by 5 mg per day at intervals of 2 to 3 days as needed; maximum 60 mg per day. In trials, divided doses of 20 mg to 30 mg per day were commonly used. Take consistently with or without food because food increases bioavailability. With a potent CYP3A4 inhibitor, follow the label's lower-dose interaction guidance.
Renal context: US labelling states that use in patients with severe renal impairment cannot be recommended; no numerical renal dose adjustment appears in the retrieved US note. (1)
United Kingdom
Indication: Short-term management of anxiety disorders and relief of symptoms of anxiety with or without accompanying depression
Dose summary: Individualise. Adults including the elderly: usual starting dose 5 mg two to three times per day; may be increased every 2 to 3 days; usual therapeutic dose 15 to 30 mg daily in divided doses; maximum recommended dose 45 mg daily in divided doses. Take at the same time each day and consistently with or without food. If administered with a potent CYP3A4 inhibitor, lower the initial dose and increase only gradually after medical evaluation. Patients should avoid consuming large quantities of grapefruit juice.
Renal context: Mild to moderate renal insufficiency (creatinine clearance 20-49 ml/min/1.72 m2): slight increase in buspirone blood levels without increased half-life; administer with caution and a low dosage twice daily is advised, with careful evaluation of response and symptoms before any increase. Do not administer to patients with creatinine clearance below 20 ml/min/1.72 m2, especially anuretic patients. Dialysis did not influence buspirone or 1-PP levels. (5)
Hepatic guidance
US labelling: steady-state AUC rose 13-fold in hepatic impairment and use in severe hepatic impairment cannot be recommended. UK labelling: buspirone is contraindicated in severe hepatic impairment; in cirrhosis higher maximum concentrations of unchanged buspirone and an increased half-life occur, so use with caution, titrate individual doses carefully to reduce central undesirable effects, and consider increased doses only after 4-5 days' experience with the prior dosage. This page does not provide an impairment-specific dose.
Overdose note
Maximum tolerated dose in normal volunteers was 375 mg/day; features of overdose include nausea, vomiting, headache, dizziness, drowsiness, tinnitus, restlessness, miosis, gastric distress, and reported mild bradycardia and hypotension; extrapyramidal symptoms have been reported after therapeutic doses and convulsions rarely. No specific antidote; buspirone is not removed by haemodialysis; empty the stomach as quickly as possible and provide symptomatic and supportive treatment with monitoring of breathing, pulse and blood pressure; suspect ingestion of multiple agents. No deaths have been reported with buspirone alone; rare fatal intentional overdoses always involved multiple drugs and/or alcohol. (1) (5)
Frequently asked questions
How long does buspirone take to work?
The sources used for this page do not state a time to onset of anxiolytic effect. The US DailyMed label, the UK SmPC and MedlinePlus were checked, and none gives an onset timeframe such as a number of weeks. What is documented is that the prescriber may start you on a low dose and gradually increase it, not more often than once every 2 to 3 days, and that it may take several weeks before you reach a dose that works for you. Do not change your dose yourself. (1) (3) (5)
Is buspirone addictive, and will I get withdrawal symptoms if I stop it?
Buspirone is not a controlled substance, and human and animal studies show no evidence of abuse potential, tolerance, or physical or psychological dependence. The label does not describe a withdrawal syndrome for buspirone. Buspirone does not share cross-tolerance with benzodiazepines and other sedative/hypnotic agents and will not block the withdrawal syndrome seen when those drugs are stopped, so UK labelling advises that patients should be gradually withdrawn from those agents before buspirone is started, especially with chronic CNS-depressant use. Any decision to stop or change treatment should be made by your prescriber. (1) (5)
Can I drink grapefruit juice while taking buspirone?
Patients taking buspirone should avoid consuming large quantities of grapefruit juice. In healthy volunteers, buspirone 10 mg with double-strength grapefruit juice (200 mL for 2 days) increased buspirone plasma concentrations (Cmax 4.3-fold, AUC 9.2-fold). Ask your pharmacist or prescriber if you are unsure about your usual intake. (1) (5)
Are US and UK buspirone doses the same?
No. US labelling gives an initial dose of 15 mg daily as 7.5 mg twice daily, increased by 5 mg per day at intervals of 2 to 3 days as needed, maximum 60 mg per day. UK labelling gives a usual starting dose of 5 mg two to three times per day, increased every 2 to 3 days, usual therapeutic dose 15 to 30 mg daily in divided doses, maximum recommended dose 45 mg daily in divided doses. The applicable local label and your prescriber's instructions apply. (1) (5)
Does buspirone work the same way as a benzodiazepine?
No. Buspirone has no significant affinity for benzodiazepine receptors, has no anticonvulsant or muscle-relaxant effect, and lacks prominent sedation. It does not share cross-tolerance with benzodiazepines and will not block benzodiazepine withdrawal, which is why UK labelling advises gradual withdrawal of those drugs before buspirone is started, especially after chronic use. (1) (5)
Can I drive while taking buspirone?
Buspirone has a moderate influence on the ability to drive and use machines and can impair cognitive function; drowsiness and dizziness are the relevant risks. UK SmPC advice to patients: the medicine is likely to affect your ability to drive, do not drive until you know how the medicine affects you, and it is an offence to drive while under the influence of this medicine. Discuss driving with your prescriber. (5)
What should I do if I miss a dose?
Take it as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue the regular schedule. Do not take a double dose. (3)
What is the mechanism of action of buspirone hydrochloride?
The mechanism of buspirone's anxiolytic action is unknown. Unlike benzodiazepines it has no anticonvulsant or muscle-relaxant effect and lacks prominent sedation. It has high affinity for 5-HT1A receptors and moderate affinity for D2 receptors, with no significant affinity for benzodiazepine receptors. Buspirone is about 95% plasma protein bound. In vitro it does not displace tightly bound drugs such as warfarin from serum proteins but may displace less firmly bound drugs such as digoxin, with unknown clinical significance. (1) (5)
References
- Buspirone Hydrochloride tablet, USP — prescribing informationDailyMed, U.S. National Library of Medicine (prescribing information, buspirone hydrochloride tablet USP) · United States · dated SPL effective 2026-03-20 · accessed 2026-10-09 · source 1
- Buspirone hydrochloride tablets — prescribing information (addendum: dosing, pregnancy, lactation, overdose, serotonin syndrome, storage)DailyMed, U.S. National Library of Medicine (prescribing information, buspirone hydrochloride tablets) · United States · dated SPL effective 2026-03-20 · accessed 2026-10-12 · source 2
- Buspirone: MedlinePlus Drug InformationMedlinePlus, U.S. National Library of Medicine · United States · accessed 2026-10-09 · source 3
- Buspirone: MedlinePlus Drug Information (addendum: missed dose and storage)MedlinePlus, U.S. National Library of Medicine · United States · accessed 2026-10-12 · source 4
- Buspirone Hydrochloride 10 mg Tablets — Summary of Product Characteristicselectronic Medicines Compendium (UK) · United Kingdom · accessed 2026-10-17 · source 5
Brand names by country
Single-ingredient buspirone hydrochloride names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- Bucapsolcapsule · 7.5 mg, 5 mg, 10 mg, 15 mg · pangea pharmaceuticals, llcregulator source
Canada
- AMB-BUSPIRONEregulator source