Key facts
Generic name
Guanfacine hydrochloride
UK brand
Intuniv, prolonged release
Class
Non-stimulant, selective alpha-2A adrenergic agonist
Licensed for
Children and adolescents aged six to seventeen
Duration
Continuous, across 24 hours
Legal status
Not a controlled drug
What guanfacine is
Guanfacine is a non-stimulant medicine for ADHD, sold in the UK as Intuniv in a prolonged-release form. It is a selective alpha-2A adrenergic agonist, which means it acts on a different receptor system from the stimulants and from atomoxetine.
In practical terms it is thought to strengthen signalling in the prefrontal cortex, the part of the brain involved in holding attention, regulating emotion and managing impulses. Guanfacine was originally a blood pressure medicine, which explains several of its effects and why blood pressure is monitored during treatment.
It gives continuous cover across the day rather than arriving in the morning and wearing off. Our guide to non-stimulant medication sets out how the group compares with the stimulant options.
Who it is prescribed for in the UK
In the UK, Intuniv is licensed for children and adolescents aged six to seventeen, as part of a wider treatment programme, where stimulants are unsuitable, not tolerated, or have been shown to be ineffective. It is not licensed for adults here.
Adult use is off-label
Guanfacine is sometimes prescribed for adults in the UK, but this is outside the licence and is a specialist decision taken where the balance of benefit and risk supports it. It is not something a GP would initiate, and it should be discussed explicitly rather than assumed.
Clinical context
Where guanfacine is often preferred
Guanfacine is frequently considered where tics are prominent, since stimulants can sometimes make tics more noticeable, and where a stimulant has caused difficulty with sleep or appetite that could not be managed by adjusting timing.
It is also considered where emotional regulation rather than attention is the more prominent difficulty, and where a heart condition or another factor makes a stimulant unsuitable.
Baseline pulse and blood pressure are checked before starting and monitored during treatment, because guanfacine can lower both. A specialist will ask about fainting, heart conditions and any medicines that also affect blood pressure.
Dosage and titration in the UK
Intuniv is usually started at 1mg once daily and increased in steps of no more than 1mg a week. The target dose depends on body weight and on response, and is reached gradually rather than quickly. Blood pressure and pulse are checked as the dose rises.
It is taken once daily, and can be taken in the morning or the evening. Many people find evening dosing better tolerated because it moves the drowsiness to a time when it matters less. Tablets are swallowed whole and not crushed, broken or chewed, because that would defeat the prolonged-release mechanism.
It should not be taken with a high-fat meal, which increases absorption. Our guide to titration explains what the appointments involve and how progress is tracked.
Never stop it abruptly
Guanfacine must be reduced gradually under supervision rather than stopped suddenly. Stopping abruptly can cause a rise in blood pressure and heart rate. If you are considering stopping, or have missed several doses, speak to your prescriber rather than simply restarting at the previous dose.
How long it takes to work
Guanfacine does not work like a stimulant. There is no clear onset an hour after a dose. The effect builds over the weeks of titration as the dose rises, and a fair judgement usually cannot be made until the target dose has been held for a few weeks.
Drowsiness is often most noticeable in the first fortnight and then settles. That pattern, where side effects arrive before benefit does, is the uncomfortable part of starting a non-stimulant, and knowing it in advance is the difference between waiting it out and abandoning a medicine that would have suited.
Once established, the effect is continuous across 24 hours. There is no afternoon drop-off to plan around and no second dose to remember.
Guanfacine side effects
Like all medicines, guanfacine can cause side effects, and not everyone gets them. Most relate to its effect on blood pressure and alertness. Our general guide to ADHD medication side effects covers all the licensed options.
Common
- Drowsiness and tiredness, especially in the first weeks
- Headache
- Stomach pain
- Lowered blood pressure and a slower heart rate
- Dizziness, particularly on standing up quickly
- Dry mouth
- Irritability
Less common
- Fainting
- Weight gain
- Disturbed sleep or unusual dreams
- Mood changes
Drowsiness is the effect most likely to interfere with school or work, and it is often solved by moving the dose to the evening. It is worth raising at review rather than enduring.
Alcohol
The Intuniv product information is explicit: patients should not drink alcohol whilst taking guanfacine. Both lower blood pressure and cause drowsiness, so the sedative effect together can be considerably stronger than expected, and dizziness on standing is more likely. Our guide to ADHD medication and alcohol sets out what the licensed information says for each medicine.
When to contact your prescriber
Seek medical advice promptly for fainting, significant dizziness, a very slow heartbeat, or any new or worsening thoughts of self-harm. Do not stop guanfacine abruptly: it is reduced gradually under supervision. Suspected side effects can also be reported through the MHRA Yellow Card scheme.
- Anxiety Whether medication helps or makes it worse
- Appetite and weight Why it happens and how it is managed
- Alcohol Risks and practical guidance
How guanfacine compares
The only ADHD medicine used here that works on the alpha-2A system.
Scroll the table sideways to see every column.
The licensing difference is the practical one for adults. Atomoxetine is licensed for adults in the UK and guanfacine is not, which is why atomoxetine is usually the first non-stimulant considered in adult treatment.
Common questions
Is guanfacine the same as Intuniv?
Intuniv is the UK brand of prolonged-release guanfacine licensed for ADHD. Guanfacine is the active ingredient. Immediate-release guanfacine used for blood pressure is a different product and is not interchangeable.
Can I drink alcohol on guanfacine?
The Intuniv product information states that patients should not drink alcohol whilst taking guanfacine. Both lower blood pressure and cause drowsiness, so together the sedative effect can be considerably stronger than expected.
Is guanfacine licensed for adults in the UK?
No. Intuniv is licensed for children and adolescents aged six to seventeen. Adult use is off-label and a specialist decision.
Why does guanfacine make me sleepy?
Drowsiness is its most common side effect, particularly in the first few weeks, and reflects how it works. It usually settles, and moving the dose to the evening solves it for many people.
Can guanfacine be stopped suddenly?
No. It should be reduced gradually under supervision, because stopping abruptly can cause blood pressure and heart rate to rise. Speak to your prescriber before stopping.
Is guanfacine a controlled drug?
No. Prescriptions are not limited to about a month, can be issued as repeats, and do not require identification at the pharmacy.
Can guanfacine be taken with a stimulant?
Combining medicines is sometimes considered by a specialist where a single medicine has not given enough benefit. It is a specialist decision, not something to arrange independently.
Important
This information is general and educational. It is not a substitute for medical advice. Decisions about starting, changing or stopping ADHD medication are always made together with a Consultant Psychiatrist following a full assessment.
Considering an ADHD assessment?
Any conversation about medication starts with a diagnosis. Our GMC-registered Consultant Psychiatrists assess adults and children. Assessments are £695 online and £1,095 in person in London or Manchester.
No GP referral needed. Appointments are usually available within weeks.
References
- Attention deficit hyperactivity disorder: diagnosis and management (NG87) National Institute for Health and Care Excellence
- Guanfacine British National Formulary
- Guanfacine NHS medicines A to Z
- Yellow Card scheme Medicines and Healthcare products Regulatory Agency
Last reviewed September 2026. Next review due September 2027.
