Guanfacine

Pronunciation: GWAHN-fa-seen.

Generic name
guanfacine
Drug class
Centrally-acting alpha2A-adrenergic receptor agonist
Form
Extended-release tablet (Intuniv, for ADHD) or immediate-release tablet (Tenex, for hypertension)
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

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

Australia: Intuniv (6) · Full directory

What guanfacine is and how it works

Guanfacine is a prescription-only medicine that works on the central nervous system to reduce sympathetic (fight-or-flight) nerve signals. The extended-release form (Intuniv) is used for ADHD in children and adolescents; the older immediate-release form (Tenex) is used for high blood pressure in adults. (1) (2)

Take guanfacine exactly as your prescriber directs, at a consistent time each day. Never change your dose or stop taking it without your prescriber's guidance -- stopping suddenly can cause your blood pressure to rise back up sharply (rebound hypertension), so any dose change or stopping needs to be planned and supervised by your prescriber.

Mechanism of action: how guanfacine works

Guanfacine is a selective agonist at central alpha2A-adrenergic receptors (with substantially higher affinity for the alpha2A subtype than alpha2B/C), reducing sympathetic outflow from the central nervous system, which lowers peripheral vascular resistance and heart rate, and is believed to improve prefrontal cortical signalling relevant to attention and impulse control in ADHD. (1) (2) (3)

What guanfacine is used for

Attention deficit hyperactivity disorder (ADHD) -- extended-release form

The extended-release form (Intuniv) is used to treat ADHD in children and adolescents aged 6-17, either on its own or alongside a stimulant medicine, as part of a broader treatment plan that may also include behavioural, educational, and social support. (1) (3)

High blood pressure (hypertension) -- immediate-release form

The older immediate-release form (Tenex) is used to help manage high blood pressure in adults, either alone or together with other blood-pressure medicines, especially thiazide-type diuretics. (2)

Before taking guanfacine

Do not take / not appropriate for

  • Do not take guanfacine if you have had a serious allergic reaction to guanfacine or any ingredient in the tablet. (all countries) (1) (2)

Tell your clinician about

  • Any history of low blood pressure, slow heart rate, fainting, or heart rhythm problems.
  • Any kidney or liver problems, which can change how much guanfacine you need.
  • Whether you are pregnant, planning pregnancy, or breastfeeding.
  • All other medicines you take, especially other blood-pressure medicines, sedatives, or medicines that affect liver enzymes (such as certain antifungal or anti-seizure medicines).
  • Any history of vomiting illnesses or difficulty keeping medicines down, which matters for children taking the extended-release form.
(1) (2) (3)

How to take guanfacine

  • Take at a consistent time each day, as your prescriber directs.
  • Swallow extended-release (Intuniv) tablets whole -- do not crush, chew, or break them, as this changes how the medicine is released.
  • Avoid taking with a high-fat meal, which can increase how much of the medicine your body absorbs.
  • Your prescriber will decide your dose gradually, adjusting over time based on your response.
  • Never change your dose or stop this medicine on your own -- always follow your prescriber's specific instructions for any dose change, and contact them first if you are considering stopping.
(1) (2)

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 for specific guidance if you miss one or more doses, especially for the extended-release ADHD form -- missing two or more doses in a row may mean your prescriber needs to restart your dose gradually rather than resuming your usual dose right away.

Overdose

Seek urgent medical attention if you think too much guanfacine has been taken, especially if there are symptoms such as extreme drowsiness, a very slow heartbeat, or fainting. (1) (2)

Side effects

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

Sleepiness (somnolence) and tiredness (fatigue), especially when starting treatment.

What to notice: Sleepiness (somnolence) and tiredness (fatigue), especially when starting treatment.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Dry mouth.

What to notice: Dry mouth.

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

Headache and stomach pain.

What to notice: Headache and stomach pain.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (3)

Low blood pressure or dizziness.

What to notice: Low blood pressure or dizziness.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (3)

Constipation.

What to notice: Constipation.

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

Serious warnings

Rebound rise in blood pressure after stopping or missing doses — high caution

Symptoms: A noticeable rise in blood pressure, headache, anxiety, or restlessness a few days after doses are missed or the medicine is stopped; rarely, this can become severe (hypertensive encephalopathy) with confusion or severe headache.

Action: Never stop or reduce this medicine without your prescriber's guidance. Your prescriber will taper the dose down gradually (typically over days to weeks) if it needs to be stopped, and will advise closely if doses have been missed. Seek urgent medical care for severe headache, confusion, or very high blood pressure readings. (1) (2) (3)

Signs of very low blood pressure, slow heart rate, or fainting — high caution

Symptoms: Feeling faint, dizzy on standing, unusually slow pulse, or actually fainting.

Action: Sit or lie down and contact your prescriber promptly; seek emergency care for an actual fainting episode or if it happens repeatedly. (1) (3)

Severe sedation affecting daily safety — high caution

Symptoms: Extreme drowsiness that interferes with school, work, or safely driving or operating machinery.

Action: Tell your prescriber -- your dose or timing may need adjustment. Avoid driving or operating machinery until you know how this medicine affects you, and avoid alcohol or other sedating medicines unless your prescriber says it is safe. (1) (2)

Interactions

  • Certain antifungal and other medicines that strongly affect liver enzymes (CYP3A4), such as ketoconazole, can significantly increase guanfacine levels -- your prescriber may need to lower your dose. (1) (3)
  • Certain seizure medicines (such as phenytoin or phenobarbital) or the antibiotic rifampin can lower guanfacine levels -- your prescriber may need to raise your dose or monitor more closely. (1) (2)
  • Other blood-pressure medicines, sedatives, and alcohol can add to guanfacine's blood-pressure-lowering and sedative effects. (1) (3)
  • Grapefruit juice can increase guanfacine levels and should generally be avoided. (3)
  • If used together with a stimulant ADHD medicine, both may need to be tapered carefully together if treatment is ever changed, under your prescriber's supervision. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

There is limited human data. Guanfacine is generally not recommended during pregnancy or in those who could become pregnant and are not using contraception, unless your prescriber judges the benefit outweighs the risk. A pregnancy exposure registry exists in the US for ADHD medicines. (1) (2) (3) (4) (5) (6)

Breastfeeding

There is limited data on whether guanfacine passes into breast milk in meaningful amounts; a risk to a breastfed infant cannot be excluded. Discuss the benefits and risks with your prescriber, and watch a breastfed infant for unusual sleepiness or feeding difficulty if this medicine is used. (1) (2) (3) (4) (5) (6)

Children

The extended-release form (Intuniv) is approved for ADHD in children and adolescents aged 6-17 (regional age ranges vary slightly); the immediate-release form (Tenex) is used in adults for hypertension. (1) (2) (3) (4) (5) (6)

Elderly

Not specifically established as a distinct population in the sources reviewed; lower starting doses and closer monitoring for low blood pressure and sedation are generally prudent in older adults. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

Liver problems can change guanfacine levels -- your prescriber may adjust your dose. (1) (2) (3) (4) (5) (6)

Renal_impairment

Reduced kidney function lowers the clearance of guanfacine -- your prescriber will generally use the lower end of the dosing range. (1) (2) (3) (4) (5) (6)

Source_ids

US-DAILYMED-INTUNIV-2026,US-DAILYMED-TENEX-2026,UK-EMC-INTUNIV-2026 (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Blood pressure and heart rate
  • Cardiovascular history review
  • Height/weight/BMI baseline in children

During treatment

  • Blood pressure and heart rate before starting, after each dose increase, and periodically during treatment.
  • Weekly monitoring during the dose-adjustment (titration) period, then regular checks (e.g. every 3 months in the first year for the ADHD form).
  • Watching for sedation, dizziness, or fainting.
  • Careful monitoring of blood pressure and pulse during any clinician-directed dose reduction or stopping.
(1) (3)

Storage

Store at controlled room temperature, 20-25°C (68-77°F); brief excursions between 15-30°C (59-86°F) are permitted. Keep in the original container, away from moisture, and out of reach 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 FDA prescribing information (Intuniv and Tenex) and UK SmPC; verify against the current full label before prescribing.

United States (Intuniv, ADHD)

Indication: ADHD, ages 6-17

Dose summary: Start 1 mg once daily; titrate in increments of no more than 1 mg/week to a target of approximately 0.05-0.12 mg/kg/day (typical range 1-7 mg once daily). Swallow whole; avoid high-fat meals. Taper by no more than 1 mg every 3-7 days when discontinuing.

Renal context: Dose reduction may be necessary in renal impairment. (1)

United States (Tenex, hypertension)

Indication: Hypertension, adults

Dose summary: Start 1 mg daily at bedtime; may increase to 2 mg after 3-4 weeks if needed; doses above 3 mg/day markedly increase adverse reactions. Use the low end of the dosing range in renal impairment.

Renal context: Reduced clearance in renal insufficiency; use low end of dosing range. Poorly dialysed -- usual doses generally appropriate for dialysis patients. (2)

United Kingdom (Intuniv, ADHD)

Indication: ADHD, ages 6-17

Dose summary: Start 1 mg daily, increase by no more than 1 mg/week; maintenance 0.05-0.12 mg/kg/day; up to 4 mg (ages 6-12) or 7 mg (ages 13-17) depending on weight. Taper by no more than 1 mg every 3-7 days when discontinuing.

Renal context: Not specifically established in the source reviewed for this dossier. (3)

Mechanism of action

Hepatic guidance

Dose reduction may be necessary in hepatic impairment, given guanfacine's substantial hepatic metabolism.

Overdose note

Overdose most often presents as exaggerated pharmacologic effects: hypotension, bradycardia, sedation, or lethargy; initial hypertension has occasionally been reported. Manage supportively with cardiovascular monitoring. (1) (2) (3)

Frequently asked questions

Can I just stop taking guanfacine if I feel better or want to stop?

No -- guanfacine should never be stopped on your own. Suddenly stopping can cause blood pressure to rebound to levels higher than before treatment, in rare cases severely. Your prescriber will taper your dose down gradually and safely if it is time to stop. (1) (2) (3)

Is guanfacine the same medicine for ADHD and for high blood pressure?

It is the same active ingredient, but sold as two different products dosed differently: an extended-release form (Intuniv) for ADHD, and an older immediate-release form (Tenex) for hypertension. They are not interchangeable without your prescriber's specific guidance. (1) (2)

Is guanfacine available in the US, UK, Europe, Canada, and Australia?

Yes, it is approved and available in the United States, United Kingdom, European Union, Canada, and Australia. Its registration status in New Zealand could not be confirmed from public regulator sources at the time of this review. (1) (3) (4) (5) (6)

What is the mechanism of action of guanfacine?

Guanfacine is a selective agonist at central alpha2A-adrenergic receptors (with substantially higher affinity for the alpha2A subtype than alpha2B/C), reducing sympathetic outflow from the central nervous system, which lowers peripheral vascular resistance and heart rate, and is believed to improve prefrontal cortical signalling relevant to attention and impulse control in ADHD. (1) (2) (3)

What is the generic name of Guanfacine?

The generic name is guanfacine. (1) (2)

What class of drug is guanfacine?

Guanfacine is classed as: Centrally-acting alpha2A-adrenergic receptor agonist. (1) (2)

References

  1. INTUNIV (guanfacine) extended-release tablets -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information, Takeda Pharmaceuticals America, Inc. · United States · accessed 2026-07-30 · source 1
  2. TENEX (guanfacine hydrochloride) tablets -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information (guanfacine hydrochloride immediate-release) · United States · accessed 2026-07-30 · source 2
  3. Intuniv prolonged-release tablets (1 mg/2 mg/3 mg/4 mg) -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Takeda UK Ltd · United Kingdom · accessed 2026-07-30 · source 3
  4. Intuniv European Public Assessment Report (EPAR) summary for the publicEuropean Medicines Agency (EMA) · European Union · accessed 2026-07-30 · source 4
  5. INTUNIV XR (guanfacine hydrochloride extended-release tablets) Product MonographHealth Canada product monograph · Canada · accessed 2026-07-30 · source 5
  6. INTUNIV guanfacine (as hydrochloride) modified release tablets -- ARTG registrationTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient guanfacine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Intuniv2 mg, 3 mg, 1 mg, 4 mg · takeda pharmaceuticals america, inc.

United Kingdom

  • Intuniv (3)MHRA licensed emc smpc confirmed · 1 mg, 2 mg, 3 mg, 4 mg · Takeda UK Ltd

Canada

  • INTUNIV XR

Australia

  • Intuniv (6)TGA ARTG registered 2017-08-22 confirmed · 1 mg, 2 mg, 3 mg, 4 mg · Takeda Pharmaceuticals Australia Pty Ltd
View brands in additional countries.

European Union

Intuniv (4)

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

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