Guanfacine

Medically reviewed by Rosanna Sutherby, PharmD on May 7, 2023
Written by Sarah Lewis, PharmD

These approved uses differ based on the form of guanfacine your doctor prescribes.

This article describes guanfacine’s uses, side effects, and more. Below you’ll also find some coupon options to help save on the cost of guanfacine.

This article doesn’t provide coupons for all forms of guanfacine. To find out more about guanfacine extended-release oral tablet, see this article.

Guanfacine may cause mild or serious side effects. More common mild side effects of guanfacine and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about guanfacine’s side effects, ask your doctor or pharmacist. You can also read the prescribing information* for guanfacine.

* To view guanfacine’s prescribing information, see the “Article resources” section below.

Mild side effects

More common mild side effects reported with some forms of guanfacine are listed below. These side effects may differ based on the form of guanfacine you take.

This article doesn’t include all possible mild side effects of the drug. To learn more about guanfacine’s side effects based on the form, see the prescribing information* for guanfacine.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Guanfacine immediate-release (IR) oral tablet’s mild side effects include:

• constipation
• dizziness
• dry mouth
• sleepiness or fatigue (low energy)
• mild allergic reaction†

Guanfacine extended-release (ER) oral tablet’s mild side effects include:

• nausea
• dizziness
• dry mouth
• sleepiness or fatigue
• mild allergic reaction†

Note: IR means the drug is released into your body right away. ER means the drug is slowly released into your body over a long period of time.

* To view guanfacine’s prescribing information, see the “Article resources” section below.
† For details about this side effect, see the “Interactions and warnings for guanfacine” section below.

Serious side effects

Serious side effects of guanfacine are listed below. These side effects may differ based on the form of guanfacine you take.

This article doesn’t include all possible serious side effects of the drug. To learn more about guanfacine’s side effects based on the form, see the prescribing information* for guanfacine.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, guanfacine’s serious side effects include:

• chest pain
• confusion
• depression
• fainting
• heart palpitations (feeling like your heart skips a beat or has an extra beat)
• increased heart rate or blood pressure after suddenly stopping the drug
• lethargy (extreme sleepiness that can make it hard to wake up)
• low blood pressure
• sudden mood changes
• problems with the heart’s electrical system, which may cause palpitations or a slow heart rate
• sexual side effects
• skin rash with peeling skin
• sleep problems, such as excessive sleepiness, nightmares, or insomnia (trouble falling or staying asleep)
• slow heart rate
• trouble swallowing
• urinary incontinence (inability to control when you urinate, which may include bedwetting)
• severe allergic reaction†

* To view guanfacine’s prescribing information, see the “Article resources” section below.
† For details about this side effect, see the “Interactions and warnings for guanfacine” section below.

The Food and Drug Administration (FDA) approves prescription drugs such as guanfacine for certain conditions. Approved uses for guanfacine are described below.

Use for attention deficit hyperactivity disorder (ADHD)

Doctors may prescribe guanfacine extended-release (ER)* oral tablet for treating ADHD. It’s used for this purpose in children ages 6–17 years old. It’s usually prescribed as a long-term treatment.

Guanfacine is not approved to treat ADHD in adults, but doctors may prescribe it off-label for this purpose. An off-label use is when doctors prescribe a drug for conditions other than its approved uses.

With ADHD, symptoms mainly involve focus and behavior. Symptoms can include problems paying attention, being overactive, or acting without thinking. All children experience these things to some degree, but with ADHD, symptoms interfere with everyday life.

Guanfacine can help increase focus and reduce the severity of ADHD symptoms. It might be prescribed together with stimulant medications for ADHD.

* ER means the drug is slowly released into your body over a long period of time.

Use for high blood pressure

Doctors may prescribe guanfacine immediate-release (IR)* oral tablet for treating high blood pressure. It’s used for this purpose in adults and children ages 12 years and older. It’s usually prescribed as a long-term treatment.

With high blood pressure, there usually aren’t any symptoms. But having high blood pressure puts you at risk of serious complications, such as heart attack or stroke. If you have high blood pressure, lowering it with medications such as guanfacine can help prevent these serious problems.

Guanfacine might be prescribed together with other medications for high blood pressure. A common combination is guanfacine and a thiazide diuretic drug, such as hydrochlorothiazide.

* IR means the drug is released into your body right away.

Below you’ll find answers to a few commonly asked questions about guanfacine.

Can guanfacine be used for anxiety, depression, cough, or autism spectrum disorder (ASD)?

Possibly. Guanfacine isn’t approved to treat anxiety, depression, cough, or ASD. But researchers have studied the drug for anxiety, depression, and ASD. So, doctors may choose to prescribe it for these purposes.

These are examples of off-label uses. An off-label use is when doctors prescribe a drug for conditions other than its approved uses.

For a cough, guanfacine isn’t likely to help. But its name is very similar to the effective cough medication guaifenesin (Mucinex).

To learn more about off-label uses of guanfacine or cough treatments, talk with your doctor.

How does guanfacine compare with other similar drugs, such as clonidine or Strattera?

Clonidine (Kapvay) and guanfacine are alpha agonist drugs (sometimes called central agonists). Like guanfacine, clonidine treats high blood pressure and ADHD. Because clonidine is in the same group of drugs as guanfacine, it can cause similar side effects. Clonidine also has similar warnings.

Atomoxetine (Strattera) also treats ADHD. Like guanfacine, it isn’t a stimulant medication. It belongs to a class of drugs called selective norepinephrine reuptake inhibitors. This gives Strattera some effects that can also help treat depression. Because it belongs to a different group of drugs, Strattera may have different side effects and warnings than guanfacine.

If you’d like to know more about other options for treating ADHD, you can talk with your doctor or pharmacist.

Is withdrawal a possible side effect of guanfacine?

Yes, it’s possible to have withdrawal symptoms (also called rebound effects) if you suddenly stop guanfacine. Withdrawal symptoms can occur when you stop taking a drug your body is dependent on. With dependence, your body needs the drug to function like usual.

Withdrawal symptoms from stopping guanfacine can include:

• agitation
• nervousness
• headache

Stopping guanfacine suddenly can also cause rebound high blood pressure and increased heart rate. This can cause serious symptoms, including extreme sleepiness, severe headache, vomiting, vision problems, and seizures. Seek immediate medical care or call 911 if you have any of these symptoms.

Do not stop taking guanfacine without talking with your doctor. Call your doctor right away if you aren’t able to take your guanfacine for any reason (such as if you’re vomiting too much).

Does guanfacine cause weight gain or weight loss?

Possibly. Weight changes weren’t reported in the prescribing information* for guanfacine immediate-release (IR) tablets. But weight gain was reported in the prescribing information* for guanfacine extended-release (ER) tablets.

Talk with your doctor if you notice weight changes after starting guanfacine. They can help determine the most likely cause. They can also suggest ways to manage it, if necessary.

Note: IR means the drug is released into your body right away. ER means the drug is slowly released into your body over a long period of time.

* To view guanfacine’s prescribing information, see the “Article resources” section below.

How does guanfacine work? And how long does it take to start working?

Guanfacine works in the brain. For high blood pressure, it affects the area of the brain that controls blood pressure. It causes heart rate to slow and blood vessels to relax. This results in lower blood pressure.

Guanfacine can have an effect on blood pressure soon after you take it. Its half-life is about 17 hours. So, most people have steady levels of guanfacine in their blood by about 4 days after starting treatment. (It takes about 5 half-lives.) But it can take a few weeks to see the drug’s full effects on blood pressure.

It isn’t known how exactly guanfacine works for ADHD. It can also take a few weeks to see whether guanfacine is helping to reduce ADHD symptoms.

To learn more about what you can expect with guanfacine, talk with your doctor or pharmacist.

The dosage of guanfacine your doctor prescribes may vary based on your condition and certain other factors. Talk with your doctor about the dosage you should take.

Taking guanfacine

Guanfacine immediate-release (IR)* oral tablet is swallowed, with or without food.

Guanfacine extended-release (ER)* oral tablet is swallowed, with or without food. But you should not take it with a high fat meal. Also, do not crush, chew, or break the ER tablet. Swallow it whole.

Your doctor will talk with you about how to take guanfacine. They’ll explain how much to take and how often. Always follow your doctor’s recommendation.

* IR means the drug is released into your body right away. ER means the drug is slowly released into your body over a long period of time.

Overdose of guanfacine

You should not take more guanfacine than your doctor prescribes. For some drugs, doing so may lead to serious side effects or overdose.

If you think you’ve taken too much guanfacine, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Below, you’ll find information about guanfacine’s possible interactions and warnings.

Interactions of guanfacine

For some medications, certain things may affect how the drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take guanfacine, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription medications
• over-the-counter medications
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for guanfacine” section just below.

Warnings for guanfacine

Guanfacine should be taken cautiously by certain people.

Guanfacine could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether guanfacine is a safe option for you. These warnings may differ based on the form of guanfacine you take.

Ask your doctor about specific warnings for guanfacine, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Guanfacine can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to guanfacine or any of its ingredients, your doctor will likely not prescribe guanfacine. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to guanfacine, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Pregnancy or breastfeeding and guanfacine

Information about guanfacine and pregnancy and breastfeeding is described below.

Guanfacine and pregnancy

It’s not known whether guanfacine should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.

If you take guanfacine for attention deficit hyperactivity disorder (ADHD) during pregnancy, you could consider joining the National Pregnancy Registry for ADHD Medications. Pregnancy registries help gather information about how certain drugs affect pregnancy.

To learn more or sign up for the registry, you can call 866-961-2388 or visit the registry website. You can also talk with your doctor.

Guanfacine and breastfeeding

It’s not known whether guanfacine should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.

You may be able to save money on your prescription for guanfacine by using our Perks discount coupons. They can be found at the end of this article.

If you have questions about how to pay for guanfacine, talk with your doctor or pharmacist.

Note: Optum Perks coupons cannot be used with insurance copays or benefits.

This article describes guanfacine’s uses and dosage, ways to save on cost, and more. Let your doctor know if you have questions about guanfacine or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• How does guanfacine compare to other drugs that could treat my condition?
• Am I at higher risk of side effects than other people taking guanfacine?
• Do any of my medications interact with guanfacine?

• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
• Guanfacine- guanfacine tablet, extended release. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/00f244f8-353d-4674-b479-26aad6b1619a/spl-doc
• Guanfacine hydrochloride- guanfacine tablet. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/fc86633a-ee61-4f16-82d4-765539a52d7e/spl-doc
• Mineur YS, et al. (2015). Antidepressant-like effects of guanfacine and sex-specific differences in effects on c-fos immunoreactivity and paired-pulse ratio in male and female mice. https://pubmed.ncbi.nlm.nih.gov/26146014/
• Politte LC, et al. (2018). A randomized, placebo-controlled trial of extended-release guanfacine in children with autism spectrum disorder and ADHD symptoms: An analysis of secondary outcome measures. https://europepmc.org/article/med/29540864
• Strawn JR, et al. (2017). Extended release guanfacine in pediatric anxiety disorders: A pilot, randomized, placebo-controlled trial. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5695796/

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.