Guanfacine (Intuniv)
What is guanfacine?
Guanfacine is known as Intuniv in the United States and Japan alike (インチュニブ on Japanese packaging). It's a non-stimulant medicine for ADHD that works through a different route from every other option: it stimulates alpha-2A receptors, which strengthens the brain's own "braking" system for attention and impulses, and settles physical hyperarousal.
How is it different from stimulant ADHD medicines?
- Not a controlled substance: no registration system, no import permits; any doctor can prescribe it
- A genuinely different route: often helpful for the impulsivity, emotional reactivity, and physical restlessness side of ADHD
- No abuse or dependence potential, and it doesn't disturb sleep the way stimulants can
- Fully startable for adults in Japan, without the registry that stimulant treatment requires
What is it used for in Japan?
ADHD (attention-deficit / hyperactivity disorder), in both children and adults.
How does it help?
By strengthening the brain's own braking system, it settles impulsivity, restlessness, and emotional spikes, and steadies attention. Like atomoxetine, it builds up gradually: the benefit comes over one to a few weeks, so keep taking it as prescribed even if you don't notice a change at first.
Guanfacine, atomoxetine, or Concerta: which is right for me?
There's no universal winner; the three trade different strengths, and the choice is individual.
| Concerta (stimulant) | Atomoxetine (non-stimulant) | Guanfacine (non-stimulant) | |
|---|---|---|---|
| Speed | Works from day one | Builds over a few weeks | Builds over one to a few weeks |
| Effect | Often somewhat stronger on average | Solid and steady, focus-led | Solid, especially on impulsivity and restlessness |
| Coverage | About 12 hours; can fade in the evening | Around the clock | Around the clock |
| Rules | Controlled medicine: registered doctors only, import permits | Ordinary medicine: any doctor, normal import rules | Ordinary medicine: any doctor, normal import rules |
| Habit-forming potential | Regulated as a stimulant | None | None |
| Getting it right now | Supply has been restricted since late 2025, and starting it new can be difficult | Supply was also disrupted, but prescribing continues | Normally available |
Among the non-stimulants, guanfacine is often preferred when tics, sleep problems, or strong emotional reactivity travel with the ADHD, while atomoxetine leans toward the attention-and-focus side. Plenty of people do well on any of the three, switching is routine, and it's a decision you make with your doctor.
What should I tell my doctor before starting?
A few situations rule it out entirely; your doctor will choose something else if any of these apply:
- A past allergic reaction to guanfacine
- Pregnancy (see the section below; guanfacine is one of the few psychiatric medicines that is formally ruled out in pregnancy)
- A significant heart block (second- or third-degree AV block, a specific heart-rhythm condition)
And tell your doctor first if any of these apply; these usually just need adjustments or a closer eye:
- Low blood pressure, a slow heartbeat, fainting episodes, or other heart concerns
- Liver or kidney problems
- Other blood-pressure medicines, or strongly sedating medicines
- Pregnant, planning to be, or breastfeeding (see the section below)
Your blood pressure and pulse are checked before starting and as the dose changes, since guanfacine lowers blood pressure and can slow the heart.
How do I take it, and what if I miss a dose?
Guanfacine is taken once a day, and the tablet is swallowed whole (don't crush or chew it; it's a slow-release design).
- If you miss a dose: just skip it if the next one is close. Never take a double dose to catch up
- Sleepiness is strongest in the first weeks and usually eases; many people take it in the evening
- Go easy on alcohol; it deepens the drowsiness
What side effects should I expect?
Most are mild and often settle, and many can be eased by adjusting the dose or timing. Not everyone gets them; the rough figures below just give a sense of how common each one is.
- Drowsiness or sleepiness (very common: around 50%): strongest early, usually easing; evening dosing helps
- Low blood pressure, or dizziness: stand up slowly, especially at first
- Headache
- Dry mouth
- Constipation
If anything is bothering you, tell your doctor; there's often a way to adjust.
Finally, one thing that is rare (most people never experience it) but good to know:
- Feeling faint, or actually fainting: sit or lie down if you feel it coming, and tell your doctor if it happens; the dose and your blood pressure will be reviewed
Will I become dependent? How do I stop safely?
No; guanfacine isn't habit-forming, but it's the one non-stimulant that should never be stopped abruptly. Stopping suddenly can cause a rebound rise in blood pressure and a fast heartbeat, so your doctor lowers it gradually. Time any change together rather than deciding alone.
Can I drive while taking it?
The Japanese label advises against driving while taking it. Guanfacine's drowsiness is significant, especially early on, and the prescribing information here instructs that patients on it shouldn't drive or operate dangerous machinery. Discuss your own situation with your doctor, particularly once the sedation has eased.
What about pregnancy and breastfeeding?
Guanfacine is not used in pregnancy; this is a formal rule, not a judgement call. If you're taking it and planning a pregnancy, or discover you're pregnant, contact your doctor promptly rather than stopping on your own (sudden stops rebound on blood pressure); the switch is planned and quick. Breastfeeding is decided case by case. Our guides to medication in pregnancy and medication while breastfeeding cover the details.