Consumer Drug Information

guanfacine

Generic Name: guanfacine (GWAHN fa seen)
Brand Names: Tenex

What is guanfacine?

Guanfacine reduces nerve impulses in your heart and blood vessels. Guanfacine works by relaxing blood vessels, which lowers blood pressure and improves blood flow.

Guanfacine is used to treat high blood pressure (hypertension). It is sometimes given together with other blood pressure medications.

Guanfacine may also be used for other purposes not listed in this medication guide.

What is the most important information I should know about guanfacine?

You should not use this medication if you are allergic to guanfacine.

Before taking guanfacine, tell your doctor if you have heart disease, coronary artery disease or a history of stroke, kidney disease, liver disease, or if you have recently had a heart attack.

Do not stop taking this medication without first talking to your doctor. If you stop taking guanfacine suddenly, your condition may become worse and you could have unpleasant symptoms.

To be sure this medication is helping your condition, your blood pressure will need to be checked on a regular basis. Do not miss any scheduled appointments.

Avoid drinking alcohol. It can increase some of the side effects of guanfacine. Guanfacine can cause drowsiness and should be taken at bedtime unless your doctor has told you otherwise.

Tell your doctor if you regularly use other medicines that make you sleepy (such as cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by guanfacine.

What should I discuss with my healthcare provider before taking guanfacine?

You should not use this medication if you are allergic to guanfacine.

Before taking guanfacine, tell your doctor if you are allergic to any drugs, or if you have:

heart disease;
coronary artery disease or a history of stroke;
kidney disease;
liver disease; or
if you have recently had a heart attack.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take guanfacine.

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. It is not known whether guanfacine passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take guanfacine?

Take this medication exactly as prescribed by your doctor. Do not take it in larger amounts or for longer than recommended. Follow the directions on your prescription label.

Guanfacine can cause drowsiness and should be taken at bedtime unless your doctor has told you otherwise.

Your doctor may occasionally change your dose to make sure you get the best results from this medication.

Do not stop taking this medication without first talking to your doctor. If you stop taking guanfacine suddenly, your condition may become worse and you could have unpleasant symptoms.

To be sure this medication is helping your condition, your blood pressure will need to be checked on a regular basis. Do not miss any scheduled appointments.

Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms, so you may not know when your blood pressure is high. You may need to use blood pressure medication for the rest of your life.

Store this medication at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember. If it is almost time for your next dose, wait until then to take the medicine and skip the missed dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include drowsiness, weakness, slow heart rate, or feeling like you might pass out.

What should I avoid while taking guanfacine?

Guanfacine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol. It can increase some of the side effects of guanfacine.

Guanfacine side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have a serious side effect such as:

fast or slow heart rate;
pounding heartbeats, chest tightness;
numbness or tingling; or
feeling like you might pass out.

Less serious side effects may include:

drowsiness, dizziness;
dry mouth;
headache;
sleep problems (insomnia);
weakness;
constipation, diarrhea;
stomach pain;
impotence, loss of interest in sex; or
mild itching or skin rash.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

Guanfacine Dosing Information

Usual Adult Dose for Hypertension:

Initial dose: 1 mg orally once a day at bedtime, when given alone or in combination with another antihypertensive drug.
Maintenance dose: 1 to 3 mg orally once a day at bedtime.

What other drugs will affect guanfacine?

The following drugs can interact with guanfacine. Tell your doctor if you are using any of these:

a barbiturate such as amobarbital (Amytal), butabarbital (Butisol), mephobarbital (Mebaral), secobarbital (Seconal), or phenobarbital (Luminal, Solfoton);
diazepam (Valium) or similar medicines such as alprazolam (Xanax), lorazepam (Ativan), temazepam (Restoril), triazolam (Halcion), and others; or
phenothiazines such as chlorpromazine (Thorazine), mesoridazine (Serentil), prochlorperazine (Compazine), thioridazine (Mellaril), and others.

This list is not complete and there may be other drugs that can interact with guanfacine. Tell your doctor about all your prescription and over-the-counter medications, vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start a new medication without telling your doctor.

Where can I get more information?

Your pharmacist can provide more information about guanfacine.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.