Clonidine

Pronunciation: KLOH-nih-deen.

Generic name
clonidine hydrochloride
Drug class
Centrally acting alpha-2 adrenergic agonist (antihypertensive)
Form
Tablet, typically 100 mcg / 0.1 mg, 150 mcg / 0.15 mg, 200 mcg / 0.2 mg, or 300 mcg / 0.3 mg depending on market
Route
Oral (tablet); also available as a transdermal patch and as an injectable solution for other clinical settings
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Catapres 100 / Catapres 150 (5), Catapres injection (5) · Full directory

What clonidine hydrochloride is and how it works

Clonidine is a prescription medicine that lowers blood pressure by reducing signals from the brain that tell blood vessels to constrict. It works centrally (in the brain and spinal cord) rather than directly on the heart or blood vessels themselves. (1) (2)

Clonidine is usually taken as a tablet, twice or more times a day. It is generally well tolerated, but two things matter for safety: it commonly causes drowsiness and dry mouth, especially when starting treatment, and stopping it suddenly can cause a dangerous rebound rise in blood pressure -- so any change to your dose should always go through your prescriber.

Mechanism of action: how clonidine hydrochloride works

Clonidine is a centrally acting alpha-2 adrenergic receptor agonist. Stimulation of these receptors in the brainstem reduces sympathetic outflow, producing decreases in peripheral vascular resistance, renal vascular resistance, heart rate, and blood pressure. (1) (2)

What clonidine hydrochloride is used for

Hypertension (high blood pressure)

Used, alone or together with other blood pressure medicines (such as thiazide diuretics), to treat essential and secondary hypertension of all grades. (1) (2) (4)

Before taking clonidine hydrochloride

Do not take / not appropriate for

  • Do not take clonidine if you have a known allergy to it. (all countries) (1) (2)
  • Do not take clonidine if you have severe bradyarrhythmia caused by sick sinus syndrome, or 2nd or 3rd degree AV (heart) block. (United Kingdom, European Union) (2)
  • Do not stop taking clonidine suddenly, or without your prescriber's guidance, because of the real risk of a dangerous rebound rise in blood pressure. (all countries) (1) (4)

Tell your clinician about

  • Any history of slow heart rate, fainting, or heart rhythm problems (including sick sinus syndrome or AV block).
  • Whether you are taking a beta-blocker, since the order in which these medicines are stopped matters for safety.
  • Any history of depression, since clonidine has been associated with mood changes in some patients.
  • Whether you are pregnant, plan to become pregnant, or are breastfeeding.
  • Any other medicines you take that cause drowsiness, including sleeping tablets, other sedatives, or alcohol use.
(1) (2)

How to take clonidine hydrochloride

  • Take exactly as prescribed, at the same times each day.
  • Never stop taking clonidine abruptly or skip several doses in a row without medical advice -- doing so can cause a rapid, dangerous rise in blood pressure.
  • If you also take a beta-blocker and both are being stopped, your prescriber will usually withdraw the beta-blocker first, then reduce clonidine gradually.
  • Be cautious with driving or operating machinery until you know how clonidine affects you, since drowsiness and dizziness are common, especially when starting treatment.
(1) (2) (4)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

Contact your prescriber if you miss one or more doses, particularly if you are unwell and cannot take your tablets as normal (for example, due to vomiting) -- do not simply resume at a higher dose on your own, since missed doses followed by resumption, or prolonged interruption, both carry blood-pressure risks that should be managed with medical guidance.

Overdose

Seek emergency medical help immediately if an overdose is suspected. Signs can include very low blood pressure, slow heart rate, extreme drowsiness or unresponsiveness, slowed or shallow breathing, and low body temperature. This is a medical emergency requiring hospital assessment and supportive treatment. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Dry mouth (around 40% of patients).

What to notice: Dry mouth (around 40% of patients).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Drowsiness/sedation (around 33%).

What to notice: Drowsiness/sedation (around 33%).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Dizziness (around 16%).

What to notice: Dizziness (around 16%).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Constipation (around 10%).

What to notice: Constipation (around 10%).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Headache and reduced tear production (dry eyes).

What to notice: Headache and reduced tear production (dry eyes).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Serious warnings

Rebound hypertension after stopping clonidine suddenly — high caution

Symptoms: Nervousness, agitation, headache, tremor, palpitations, and a rapid rise in blood pressure, sometimes appearing within 12 to 48 hours of stopping.

Action: Seek urgent medical attention if these symptoms occur after missing doses or stopping treatment. Never stop clonidine abruptly -- your prescriber will reduce the dose gradually over several days. Rare but serious complications, including hypertensive encephalopathy, stroke, and death, have been reported with abrupt withdrawal. (1) (4)

Signs of a very slow heart rate or heart block — high caution

Symptoms: Marked slowing of the heart rate, fainting, or dizziness on standing.

Action: Contact your prescriber promptly, or seek emergency care if severe -- this risk is higher if you also take other medicines that slow the heart rate (such as beta-blockers or certain calcium channel blockers). (1) (2)

Severe drowsiness or sedation — moderate

Symptoms: Excessive sleepiness affecting your ability to drive or function safely.

Action: Avoid driving or operating machinery until you know how clonidine affects you; avoid alcohol and other sedating medicines unless cleared by your prescriber. (1) (2)

New seizures after starting clonidine (rare, monitored safety signal) — moderate

Symptoms: A new seizure or seizure-like episode after starting clonidine.

Action: Seek medical attention for any new seizure. New Zealand's medicines regulator investigated a small number of such reports and concluded the overall benefit-risk balance for clonidine remains positive for its approved uses, but any new seizure after starting this medicine should still be reported to your prescriber. (6)

Signs of a serious allergic reaction — emergency

Symptoms: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread rash or hives.

Action: Seek emergency medical help immediately. (2)

Interactions

  • Alcohol, barbiturates, sedatives, and other CNS depressants can increase drowsiness and sedation. (1)
  • Tricyclic antidepressants may reduce clonidine's blood-pressure-lowering effect. (1)
  • Beta-blockers, digitalis, and calcium channel blockers (such as diltiazem or verapamil) can increase the risk of a very slow heart rate or heart block when combined with clonidine -- and the order of stopping these medicines matters if both are being discontinued. (1) (2)
  • Methylphenidate combined with clonidine has been associated with reports of serious adverse events, including sudden death -- tell your prescriber if you or your child take both. (2)
  • Other antihypertensive medicines can add to clonidine's blood-pressure-lowering effect. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Human pregnancy data are limited; clonidine crosses the placenta. Use only if the potential benefit justifies the potential risk, and only under your prescriber's guidance. (1) (2) (3) (4) (5) (6)

Breastfeeding

Clonidine passes into breast milk. UK guidance advises against breastfeeding during treatment; US labelling advises caution -- discuss your individual situation with your prescriber. (1) (2) (3) (4) (5) (6)

Children

Not approved for routine use in children and adolescents in several of the markets reviewed (e.g. UK, New Zealand); the US label states safety and effectiveness have not been established in adequate, well-controlled trials for this standard tablet, and notes that children are particularly susceptible to hypertensive episodes if doses are abruptly missed. (1) (2) (3) (4) (5) (6)

Elderly

May be started on a lower initial dose, reflecting increased sensitivity to blood-pressure-lowering and sedative effects. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

Specific dose-adjustment data were not found in the sources reviewed for this dossier; use with the same caution and clinician oversight as any other population, and discuss with your prescriber. (1) (2) (3) (4) (5) (6)

Renal_impairment

Lower initial doses are generally recommended with careful monitoring; clonidine is minimally cleared by haemodialysis. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Baseline blood pressure and heart rate
  • Review of other medicines that slow heart rate or cause sedation
  • Any history of heart rhythm problems

During treatment

  • Regular blood pressure and heart rate checks, especially during dose titration.
  • Watch for excessive drowsiness, especially when starting treatment or increasing the dose.
  • Never allow treatment to be interrupted for an extended period without medical advice, given the rebound-hypertension risk on abrupt withdrawal.
(1) (2)

Storage

Store at room temperature, in the original packaging, out of reach and sight of children.

Study the drug class: Centrally acting antihypertensives · CNS stimulants and ADHD agents

Professional information

Clinician-facing context only, sourced from the current US DailyMed Catapres label, the UK generic clonidine SmPC, and the Health Canada Catapres product monograph; verify against the current full label before prescribing.

United States / Canada

Indication: Hypertension

Dose summary: Initial 0.1 mg twice daily, titrated by 0.1 mg/day increments; usual maintenance 0.2-0.6 mg/day divided; max effective dose 2.4 mg/day (rarely used).

Renal context: Lower initial doses with careful monitoring in renal impairment; minimal haemodialysis clearance. (1) (4)

United Kingdom / European Union

Indication: Essential and secondary hypertension

Dose summary: Initial 50-100 mcg three times daily, gradually increased every 2-3 days; usual range 300-1200 mcg/day.

Renal context: Dosage adjusted according to individual response and degree of renal dysfunction. (2)

Mechanism of action

Hepatic guidance

No specific hepatic dose-adjustment guidance was identified in the sources reviewed for this dossier.

Overdose note

Overdose can cause hypotension, bradycardia, CNS depression, respiratory depression, and hypothermia; management is supportive with continuous cardiovascular and respiratory monitoring. (1) (2)

Frequently asked questions

Why can't I just stop taking clonidine if I feel better?

Stopping clonidine suddenly can cause a rebound rise in blood pressure, sometimes with agitation, headache, and tremor, and in rare cases serious complications such as hypertensive encephalopathy or stroke. Your prescriber will always taper the dose down gradually over several days rather than stopping it abruptly. (1) (4)

Is clonidine available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes. Oral clonidine for hypertension is confirmed authorised in all of these regions, generally as Catapres (or Catapresan in parts of the EU) and as generic clonidine hydrochloride tablets. (1) (2) (3) (4) (5) (6)

Has clonidine been linked to seizures?

New Zealand's medicines regulator (Medsafe) investigated a small number of seizure reports in people taking clonidine. After review, it found no established causal mechanism, concluded the benefit-risk balance for clonidine remains positive for its approved uses, and advised patients not to stop treatment on their own. This was a genuinely investigated and closed safety-monitoring signal, not a new, unresolved risk. (6)

What is the mechanism of action of clonidine hydrochloride?

Clonidine is a centrally acting alpha-2 adrenergic receptor agonist. Stimulation of these receptors in the brainstem reduces sympathetic outflow, producing decreases in peripheral vascular resistance, renal vascular resistance, heart rate, and blood pressure. (1) (2)

What is the generic name of Clonidine?

The generic name is clonidine hydrochloride. (1) (2)

What class of drug is clonidine hydrochloride?

Clonidine is classed as: Centrally acting alpha-2 adrenergic agonist (antihypertensive). (1) (2)

References

  1. CATAPRES (clonidine hydrochloride) tablets -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH) · United States · accessed 2026-07-30 · source 1
  2. Clonidine Hydrochloride 100 microgram Tablets -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-30 · source 2
  3. Clonidine -- list of nationally authorised medicinal products (PSUSA/00000813)European Medicines Agency (EMA) -- Periodic Safety Update Report Single Assessment (PSUSA) for clonidine · European Union · accessed 2026-07-30 · source 3
  4. CATAPRES (clonidine hydrochloride) and generic CLONIDINE/APO-CLONIDINE Product MonographsHealth Canada product monographs · Canada · accessed 2026-07-30 · source 4
  5. CATAPRES 100 (ARTG 17921), CATAPRES 150 (ARTG 78376), and CATAPRES injection (ARTG 17919)Therapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-30 · source 5
  6. CATAPRES (tablets/injection), CATAPRES-TTS (patch), and generic CLONIDINE (Teva) New Zealand Data SheetsMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient clonidine 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

  • Clonidine transdermal system.3 mg/d, .2 mg/d, .1 mg/d · trupharma, llc
  • Catapres-TTS-1.1 mg/d, .2 mg/d, .3 mg/d · technomed inc.
  • JAVADIN20 ug/mL · azurity pharmaceuticals, inc.
  • CLONIDINE HCI100 ug/mL · hf acquisition co llc, dba healthfirst
  • Duraclon.1 mg/mL · mylan institutional llc
  • ONYDA XR.1 mg/mL · nextwave pharmaceuticals, inc
  • Nexiclon XR.17 mg · rosemont pharmaceuticals llc

United Kingdom

  • Clonidine Hydrochloride (generic tablets/oral solution) (2)MHRA licensed emc smpc confirmed · 25 mcg, 100 mcg · multiple UK generic manufacturers

Canada

  • Catapres (4)Health Canada approved confirmed · 0.1 mg, 0.2 mg · Boehringer Ingelheim (Canada)
  • APO-CLONIDINE (generic) (4)Health Canada approved confirmed · 0.1 mg, 0.2 mg · Apotex Inc.

Australia

  • Catapres 100 / Catapres 150 (5)TGA ARTG registered confirmed · 100 mcg, 150 mcg · Clinect Pty Ltd (ARTG 17921, 78376)
  • Catapres injection (5)TGA ARTG registered confirmed · 150 mcg/mL · ARTG 17919

New Zealand

  • Catapres (tablets/injection) (6)Medsafe registered confirmed · 100 mcg, 150 mcg · Boehringer Ingelheim (NZ)
  • Catapres-TTS (transdermal patch) (6)Medsafe registered confirmed · 3.5 cm2, 7.0 cm2, 10.5 cm2 · Boehringer Ingelheim (NZ)
  • Clonidine (Teva, generic) (6)Medsafe registered confirmed · 100 mcg · Teva
View brands in additional countries.

European Union

Catapresan (3)

This page provides general reference information about clonidine and is not a substitute for advice from the prescriber managing your treatment. All dosing and treatment decisions, especially any change or stop in treatment, should be made with your prescriber.

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