Health Guide

Guanabenz (By mouth)

Guanabenz (GWAHN-a-benz)

Treats high blood pressure.

Brand Name(s):

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to guanabenz in the past.

How to Use This Medicine:


  • Take this medicine exactly as your doctor ordered. Even if you feel fine your blood pressure can still be high.
  • May be taken with or without food.

If a dose is missed:

  • Take the missed dose as soon as you remember.
  • Skip the missed dose if it is almost time for your next regular dose.
  • If you miss more than two doses in row, talk with your doctor.
  • You should not use two doses at the same time.

How to Store and Dispose of This Medicine:

  • Store at room temperature, away from heat, moisture, and direct light.
  • Keep all medicine out of the reach of children.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Tell your doctor if you are taking a beta blocker such as Inderal®, Tenormin®, Lopressor®, Visken®, or Corgard®.
  • Avoid drinking alcohol while taking this medicine.

Warnings While Using This Medicine:

  • Check with your doctor before taking if you have heart, kidney, or liver disease.
  • Talk with your doctor before taking this medicine if you are pregnant or breastfeeding.
  • Do not stop taking this medicine suddenly, because you may need to take smaller and smaller doses before completely stopping the medicine.
  • Tell your doctor or dentist that you are taking guanabenz before having any kind of surgery.
  • Guanabenz can make some people dizzy or drowsy, be careful if you drive a car or operate machinery.
  • To avoid dizziness while taking this medicine, stand up slowly from a sitting or lying position.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Irregular heartbeat
  • Chest pain
  • Trouble breathing
  • Skin rash, severe itching or hives
  • Severe dizziness or fainting

If you notice these less serious side effects, talk with your doctor:

  • Drowsiness or dizziness
  • Dry mouth, increased sweating
  • Headache, nervousness, or restlessness
  • Diarrhea
  • Breast swelling in men
  • Sexual difficulties
  • Nausea or vomiting

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 4/4/2018
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