Guanfacine is a non-stimulant ADHD medication with a different mechanism from atomoxetine and from stimulants. It is sold in the UK as Intuniv and as generic guanfacine modified-release [2]. This article covers how guanfacine works, the situations where it is the right fit, what the titration looks like, and the side effects that warrant planning around.
What guanfacine is
Guanfacine is a selective alpha-2A adrenergic receptor agonist. It works on the prefrontal cortex by binding to alpha-2A receptors on the postsynaptic neurons, which strengthens signal transmission in the circuits that handle working memory, attention and behavioural regulation [2]. The mechanism is quite different from stimulants (which act on dopamine and noradrenaline reuptake and release) and from atomoxetine (which inhibits noradrenaline reuptake).
The UK licensed formulation is modified-release guanfacine, taken once daily. It is licensed in the UK for the treatment of ADHD in children and adolescents aged 6 to 17 where stimulants are not suitable, not tolerated, or have proved insufficient [2]. Guanfacine is not licensed in the UK for adult ADHD, although off-label use occurs in specialist settings; NICE NG87 references it as a recognised non-stimulant option [1].
Guanfacine is not a controlled drug.
When guanfacine is the right fit
Several clinical pictures make guanfacine a reasonable choice in children and adolescents [1, 2]:
- ADHD with co-occurring tics or Tourette syndrome where stimulants have worsened tics
- Significant difficulty with emotional regulation, irritability or oppositional features alongside ADHD
- ADHD with co-occurring sleep difficulties where the sedating side effect of guanfacine is helpful
- A history of stimulant intolerance and an inadequate response to atomoxetine
- Significant anxiety symptoms that have not responded well to stimulants
Under NICE NG87, the usual order in children and adolescents is methylphenidate first, lisdexamfetamine second, atomoxetine third, guanfacine fourth, with clinical judgement allowed to reorder these where the picture demands it [1]. Guanfacine in combination with a stimulant is sometimes used in specialist practice where partial response to either alone is incomplete.
The Cortese 2018 network meta-analysis included guanfacine and found a moderate effect size for children and adolescents, lower than stimulants but clinically meaningful, with a different side-effect profile [4].
What treatment looks like
Guanfacine titration is the slowest of the licensed UK ADHD medications. Specific doses are a prescribing decision and depend on weight and clinical picture, but the shape of ADHD medication and prescribing with NeuroFX for guanfacine usually involves:
- A low starting dose taken once daily, often in the evening
- A dose increase no sooner than once weekly during titration [2]
- Continued review of blood pressure, heart rate, weight and somnolence at every increase
- A working dose typically reached over six to eight weeks
- A formal review at three months once the working dose is stable
The slow titration reflects the cardiovascular profile: guanfacine lowers blood pressure and heart rate (in contrast to stimulants and atomoxetine, which raise both). A rapid increase risks fainting, dizziness, and excessive sedation.
The clinical benefit usually becomes apparent across the first four to six weeks. Like atomoxetine, guanfacine builds its effect over time rather than producing the same-day response of a stimulant.
Common side effects
The BNFc and BNF list the common adverse effects of guanfacine [2, 3]. They include:
- Sleepiness, particularly in the first two to four weeks (this often settles, and is sometimes useful for patients with co-occurring sleep difficulty)
- Low blood pressure and dizziness, especially on standing
- Low heart rate
- Headache
- Fatigue
- Reduced appetite (less marked than with stimulants)
- Stomach upset
- Dry mouth
- Mood changes in some patients
Most early effects settle within four to six weeks. Persistent or significant cardiovascular effects warrant prescriber review and may prompt a dose adjustment or a switch.
A specific feature of guanfacine is that the dose must not be stopped suddenly. Abrupt withdrawal can cause rebound rises in blood pressure and heart rate [2]. Any plan to stop guanfacine should be discussed with the prescriber and follows a gradual taper.
Monitoring under NICE NG87
The monitoring requirements for guanfacine [1, 2] are similar in structure to other ADHD medications but with a cardiovascular emphasis pointed in the opposite direction. Baseline measurements at initiation include blood pressure, heart rate and weight (and height in children). At each titration step and at each review, blood pressure and heart rate are remeasured. Symptoms of dizziness on standing, fainting, or excessive sedation are flagged at each visit.
Long-term review is at least annual. Children also have a growth check at each review.
Where guanfacine fits in the wider plan
Guanfacine is sometimes described as "the last option", which understates its usefulness in specific situations. For a child with ADHD plus tics, ADHD plus marked emotional dysregulation, or ADHD plus persistent sleep difficulty, guanfacine can be the better fit than a stimulant or atomoxetine. The choice between options is a clinical conversation that takes the whole picture into account, not a single linear pathway.
It is also worth noting that guanfacine works through a circuit-strengthening mechanism that may improve aspects of working memory and impulse regulation that stimulants address less directly [2]. For some patients this is the most useful aspect of the medication.
Practical notes
- Guanfacine is not a controlled drug. Prescriptions can include repeats and are not subject to the 28-day quantity limits.
- The modified-release tablet should be swallowed whole and not crushed, chewed or broken [2]. Taking with a high-fat meal increases absorption substantially and is generally avoided.
- Do not stop guanfacine abruptly. A taper, planned with the prescriber, is required.
- Combination with stimulants is a specialist decision; never combine medications without prescriber authorisation.
- Alcohol amplifies the sedation and the cardiovascular effects of guanfacine; conservative consumption is sensible.
What this means in practice
- Guanfacine is a non-stimulant ADHD medication with a different mechanism from atomoxetine and stimulants, acting on prefrontal alpha-2A receptors.
- It is licensed in the UK for children and adolescents aged 6 to 17 where stimulants are not suitable, not tolerated, or have not worked.
- Titration is slow by design, with weekly dose increases and careful monitoring of blood pressure and heart rate.
- Most clinical benefit emerges over four to six weeks.
- Do not stop guanfacine abruptly. Always taper under prescriber direction.
When to speak to a professional
Speak to your GP, your prescriber or NHS 111 if a new symptom appears that worries you, if dizziness on standing is significant, or if mood, sleep or appetite changes are not settling. Seek urgent help via 999 or A&E for fainting, chest pain, or any acute mental health crisis. For UK families and adults wanting specialist guidance, NeuroFX offers paediatric ADHD assessment for children aged 6 and upwards alongside private adult ADHD assessment.
Sources
- NICE. Attention deficit hyperactivity disorder: diagnosis and management. NG87. National Institute for Health and Care Excellence. https://www.nice.org.uk/guidance/ng87
- British National Formulary for Children. Guanfacine. https://bnfc.nice.org.uk/drugs/guanfacine/
- British National Formulary. Guanfacine. https://bnf.nice.org.uk/drugs/guanfacine/
- Cortese S, Adamo N, Del Giovane C, et al. Comparative efficacy and tolerability of medications for attention-deficit/hyperactivity disorder in children, adolescents, and adults: a systematic review and network meta-analysis. Lancet Psychiatry. 2018;5(9):727-738.
