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Uses

What is guanfacine used for?

Guanfacine is commonly used to treat high blood pressure and attention deficit hyperactivity Disorder (ADHD).

Guanfacine may also be used for other conditions as determined by your healthcare provider.

How does guanfacine work (mechanism of action)?

Guanfacine lowers your heart rate and relaxes your blood vessels. This helps to lower your blood pressure. The exact way guanfacine works for treating attention deficit hyperactivity Disorder (ADHD) is not fully understood.

How is guanfacine supplied (dosage forms)?

Brands and other names

  • Intuniv

Dosage forms and strengths

  • 1 mg extended-release oral tablets
  • 2 mg extended-release oral tablets
  • 3 mg extended-release oral tablets
  • 4 mg extended-release oral tablets
  • 1 mg oral tablets
  • 2 mg oral tablets

How should I store guanfacine?

Guanfacine should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of guanfacine?

The most common side effects of guanfacine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dry mouth
  • Drowsiness (or sleepiness) (see below)
  • Dizziness
  • Constipation 
  • Low blood pressure (see below)
  • Nausea 
  • Trouble sleeping
  • Stomach pain
  • Irritability (extended-release tablets)
  • Vomiting (extended-release tablets)
  • Slow heart rate (see below) 

There may be other side effects of guanfacine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of guanfacine?

While less common, the most serious side effects of guanfacine are described below, along with what to do if they happen.

Severe Allergic Reactions. Guanfacine may cause allergic reactions, which can be serious. Stop taking guanfacine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Heart Rate Changes. Guanfacine can make your heart beat slower than normal (bradycardia). Check your heart rate regularly before and during your guanfacine treatment. Avoid other drugs that affect your heart rate. Be sure to avoid becoming dehydrated or overheated. Call your healthcare provider right away if you have any of the following symptoms of bradycardia. 

  • Feeling lightheaded, dizziness, or fainting
  • Confusion
  • Feeling weak or easily tired 
  • Chest pain
  • Shortness of breath

Heart Rhythm Changes. Guanfacine may cause heart rhythm problems that can lead to an irregular heartbeat and fainting. In rare cases, this may cause the heart to suddenly stop beating (cardiac arrest). Some people have a higher risk of this, including people with existing heart disease or who take other medicines that affect the heart. Get emergency help if you have any of the following signs of heart rhythm changes.

  • Chest pain
  • Shortness of breath
  • Feeling dizzy, lightheaded, or fainting
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat

Low Blood Pressure Upon Standing (Orthostatic Hypotension). Guanfacine may cause a sudden drop in blood pressure when standing up from a seated or lying position. To help prevent this, be careful not to get up too quickly. If you feel dizzy, sit or lie down right away until the dizziness stops, then take your time getting up again. Check your blood pressure regularly before and during your guanfacine treatment. Avoid other drugs that may lower your blood pressure. Be sure to avoid becoming dehydrated or overheated. Tell your healthcare provider right away if you have any of the following symptoms of orthostatic hypotension.

  • Dizziness, feeling lightheaded, or fainting upon standing
  • Blurred vision
  • Confusion
  • Feeling weak

Sleepiness. Guanfacine can make you sleepy. Be aware of any other medications you use that can also cause sleepiness. Be sure to separate these medications if possible. Do not drive or do other activities that require alertness or coordination until you know how guanfacine affects you.

Warnings & Precautions

Who should not use guanfacine?

Allergies to Ingredients. People who are allergic to any of the following should not take guanfacine.

  • Guanfacine
  • Intuniv
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Intuniv or the specific generic guanfacine products they stock.

What should I know about guanfacine before using it?

Do not take guanfacine unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share guanfacine with other people, even if they have the same condition as you. It may harm them.

Keep guanfacine out of the reach of children.

Do not crush, chew, or break guanfacine extended-release tablets (Intuniv) before swallowing.

Do not stop taking guanfacine without talking to your healthcare provider. Stopping guanfacine may cause a sudden increase in blood pressure. If you need to stop taking guanfacine, your healthcare provider will give you instructions on how to stop the medicine.

Guanfacine can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how Guanfacine affects you.

What should I tell my healthcare provider before using guanfacine?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if guanfacine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

Other Medicines and Supplements. Guanfacine may interact with other medicines and supplements. Before using guanfacine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how guanfacine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take guanfacine while you are pregnant or trying to get pregnant. 

If you become pregnant while taking guanfacine extended-release (Intuniv), you can register for the National Pregnancy Registry for ADHD Medications by calling 866-961-2388. This registry collects safety information about the use of ADHD medicines during pregnancy.

Breastfeeding. It is not known if guanfacine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take guanfacine while breastfeeding. They may recommend monitoring your child for drowsiness, sleepiness, and poor feeding if you are breastfeeding during your guanfacine treatment.

Interactions

Does guanfacine interact with foods or drinks?

Avoid taking guanfacine with high-fat meals. This can raise guanfacine levels in the body.

It is best to limit the amount of alcohol you drink while taking guanfacine. The risk of drowsiness and dizziness may be increased if you drink alcohol while taking guanfacine.

Does guanfacine interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking guanfacine.

  • A barbiturate, such as phenobarbital, butalbital, or primidone which is a medicine that may be used to treat insomnia, migraines, or seizures
  • A benzodiazepine, which is a medicine used for certain mental health conditions
  • An antipsychotic, which is a medicine for certain mental health conditions
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety
  • A medicine for high blood pressure
  • Ketoconazole, which is a medicine used for fungal infections

Many other medicines may alter the blood levels of Guanfacine. Tell your healthcare provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with guanfacine. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much guanfacine?

If you or someone else has used too much guanfacine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of guanfacine?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

If you miss two or more doses, talk with your healthcare provider. You may need to restart guanfacine with a lower dose.