Medication Guide
Guanfacine ER (Intuniv) Side Effects and Uses
A plain-language guide to Guanfacine ER, a non-stimulant ADHD medication (alpha-2A agonist). Learn how it helps, what it treats, how to take it and which side effects to know about.
Quick answer. Guanfacine ER (Intuniv) is a non-stimulant ADHD medication (alpha-2A agonist). Common guanfacine er side effects include drowsiness, tiredness, dizziness or lightheadedness and low blood pressure. The rare but serious ones, and when to get help, are listed under guanfacine er side effects below. Never stop or change your dose on your own.
How Guanfacine ER Can Help You
Guanfacine extended-release is a non-stimulant ADHD medicine. It works on alpha-2A receptors in the front of the brain. This strengthens the brain's own control over attention, impulses and emotional reactions. It helps most with the hyperactive and impulsive side of ADHD, such as a quick temper, big reactions and restlessness. It can be used alone or added to a stimulant.
Guanfacine started out as a blood pressure medicine, so it tends to calm rather than energize. Benefits build over a few weeks of daily use. Families often notice fewer blowups and smoother transitions first, then steadier attention. It is not a controlled substance and has no misuse risk. Intuniv is FDA-approved for ADHD in children and teens 6 to 17.
Uses for Guanfacine ER
- ADHD in children and teens, alone or with a stimulant
- Hyperactivity and impulsive actions
- Big emotional reactions in ADHD (off-label)
- Tic disorders (off-label)
- ADHD in adults (off-label)
- Poor sleep or evening rebound from stimulants (off-label)
- Hyperarousal in PTSD (off-label)
How to Take Guanfacine ER
Your prescriber decides your dose and any changes, usually starting low and going slowly. Take it at the same time every day, morning or evening. Evening dosing is common if it makes you sleepy. Swallow the tablet whole. Do not crush or chew it, and do not take it with a high-fat meal, which raises how much you absorb. Limit alcohol, which adds to drowsiness and low blood pressure.
Guanfacine is not a controlled substance, but you must not stop it suddenly after regular use. Stopping all at once can cause blood pressure and heart rate to rebound. Your prescriber will taper it slowly. If you miss a dose, take the next one on schedule without doubling. If you miss two or more days, call your prescriber, since you may need to restart slowly.
Guanfacine ER Side Effects
Common Side Effects
- Drowsiness, most of all early on
- Tiredness
- Dizziness or lightheadedness
- Low blood pressure
- Dry mouth
- Headache
- Stomachache or nausea
- Constipation
- Slower heart rate
Serious: Get Medical Help Promptly
- Very low blood pressure or fainting.
- Very slow heart rate.
- Rebound high blood pressure if stopped suddenly.
- Heavy sedation or confusion.
- Allergic reaction (rash, swelling).
How Guanfacine ER Works
Guanfacine tunes alpha-2A receptors in the prefrontal cortex. That helps brain signals for focus and self-control come through more clearly. It also lowers the body's fight or flight tone, which is why it can lower blood pressure and heart rate.
The extended-release form is made to give steady levels all day from one dose. It is not the same as the older short-acting guanfacine tablets used for blood pressure. The two cannot be swapped milligram for milligram.
Before You Start and Stopping Safely
Tell your prescriber about low blood pressure, fainting, a slow heartbeat or other heart problems. Share all medicines. Some antifungal drugs, antibiotics and seizure medicines can change guanfacine levels. Other sedating medicines add to drowsiness.
Guanfacine should always be tapered, not stopped. Keep refills on time so you do not run out. Stand up slowly and drink enough fluids, most of all in hot weather. Learn more on our child and teen ADHD page.
Is Guanfacine ER Right for You?
Only a full evaluation with a prescriber can tell you if Guanfacine ER fits your symptoms, history and goals. Harpal Singh, PMHNP-BC offers psychiatric evaluations and ongoing medication management by telehealth anywhere in California.
SCHEDULE AN APPOINTMENT CALL (888) 457-8124
Related Medication Guides
Other guides in the same group, written the same simple way. Being in one group does not mean you can swap one medicine for another.
- Atomoxetine (Strattera), non-stimulant ADHD medication (norepinephrine reuptake inhibitor)
- Clonidine ER (Kapvay), non-stimulant ADHD medication (alpha-2 agonist)
- Dexmethylphenidate (Focalin), stimulant (methylphenidate)
- Lisdexamfetamine (Vyvanse), stimulant (amphetamine prodrug)
- Methylphenidate (Ritalin), stimulant (methylphenidate)
- Mixed Amphetamine Salts (Adderall), stimulant (amphetamine)
FAQ
Questions About Guanfacine ER
How is guanfacine different from a stimulant?
Stimulants raise dopamine and norepinephrine broadly. Guanfacine fine-tunes receptors in the front of the brain to strengthen self-control. It calms rather than energizes, works around the clock once built up and has no misuse risk.
Will guanfacine make my child (or me) sleepy all day?
Sleepiness is the most common early side effect, and it often eases over the first few weeks. Starting low, going slowly and taking it in the evening are common ways prescribers manage it. Tell your prescriber if it does not improve.
Can guanfacine be combined with Adderall or Vyvanse?
Yes. Intuniv is FDA-approved as an add-on to stimulants, and the pairing is common. The stimulant drives focus, while guanfacine smooths impulses, rebound and evening behavior. Many people get better coverage from the pair than from either alone.
Why can't I just stop taking it?
Guanfacine lowers blood pressure, so stopping suddenly can cause a rebound jump in blood pressure and heart rate. Your prescriber will taper it slowly whenever it is stopped.
Does guanfacine help with emotional outbursts?
It is one of the better options for the big emotions that often come with ADHD, like quick frustration and slow recovery. Families often notice fewer meltdowns and smoother evenings before they notice changes in attention.
Can adults take guanfacine for ADHD?
Intuniv is FDA-approved for children and teens 6 to 17. Some prescribers use it for adults off-label when it fits. Your prescriber decides based on your health and needs.
Can I drink alcohol while taking guanfacine?
It is best to limit or avoid it. Alcohol adds to drowsiness and can lower blood pressure further. That raises the risk of dizziness and fainting.
Can guanfacine be prescribed by telehealth in California?
Yes. Guanfacine is not a controlled drug, so it can be prescribed by telehealth after a full evaluation. Blood pressure and heart rate checks are part of follow-up care.