Medication Quick Search
My Medicine List Your Hospital Pharmacist Medication Tips and Tools

Guanabenz

(gwahn' a benz)

Brand Name(s): Wytensin®; also available generically

WHY is this medicine prescribed?

Guanabenz is used to treat high blood pressure. It is in a class of medications called centrally acting alpha2A-adrenergic receptor agonists. Guanabenz works by decreasing your heart rate and relaxing the blood vessels so that blood can flow more easily through the body.

High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

Are there OTHER USES for this medicine?

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

HOW should this medicine be used?

Guanabenz comes as a tablet to take by mouth. It usually is taken twice a day at evenly spaced intervals. Take guanabenz at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take guanabenz exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Guanabenz controls high blood pressure but does not cure it. Continue to take guanabenz even if you feel well. Do not stop taking guanabenz without talking to your doctor. If you suddenly stop taking guanabenz you may develop high blood pressure and experience unwanted side effects.

What SPECIAL PRECAUTIONS should I follow?

Before taking guanabenz,

  • tell your doctor and pharmacist if you are allergic to guanabenz, any other medications, or any of the ingredients in guanabenz tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: amitriptyline, clomipramine (Anafranil), desipramine (Norpramin), doxepin (Silenor), imipramine (Tofranil, Surmontil), medications for high blood pressure and sleep, nortriptyline (Pamelor), protriptyline (Vivactil), and trimipramine (Surmontil).
  • tell your doctor if you have had a recent heart attack, or have coronary artery disease, or kidney or liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking guanabenz, call your doctor.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking guanabenz.
  • you should know that this medication may make you drowsy or dizzy. Do not drive a car or operate machinery until you know how this medication affects you.
  • ask your doctor about the safe use of alcohol while you are using guanabenz. Alcohol can make the side effects from guanabenz worse.
  • talk to your doctor about the risks and benefits of taking guanabenz if you are 65 years of age or older. Older adults should not usually take guanabenz because it is not as safe or effective as other medications that can be used to treat the same condition.

What SPECIAL DIETARY instructions should I follow?

Your doctor may prescribe a low-salt or low-sodium diet. Follow these directions carefully.

What should I do IF I FORGET to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Guanabenz may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • dry mouth
  • drowsiness
  • dizziness
  • weakness
  • headache
  • decreased sexual ability
  • upset stomach

If you experience any of the following symptoms, call your doctor immediately:

  • fainting
  • increased or decreased heartbeat
  • irregular heartbeat
  • swollen ankles or feet

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor and the laboratory. Your blood pressure should be checked regularly to determine your response to guanabenz.

Your doctor may ask you to check your pulse (heart rate) daily and will tell you how rapid it should be. Ask your doctor or pharmacist to teach you how to take your pulse. If your pulse is slower or faster than it should be, call your doctor before taking the medication that day.

To avoid dizziness or faintness, get up slowly from a sitting or lying position. If you feel dizzy or faint at any time, you should lie or sit down.

To relieve dry mouth caused by guanabenz, chew gum or suck sugarless hard candy.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

This branded product is no longer on the market. Generic alternatives may be available.


This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists® represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists® makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists® does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

Pronunciation Guide for Drug Names is used with permission. © 2009. The United States Pharmacopeial Convention. All Rights Reserved.

AHFS® Patient Medication Information™. © Copyright, 2020. The American Society of Health-System Pharmacists®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: August 15, 2018.