Reviewed on 9/23/2021

What Is Guanabenz Used For and How Does it Work?

Guanabenz is used to treat high blood pressure (hypertension).

Guanabenz is available under the following different brand names: Wytensin.

What Are the Dosages of Guanabenz?

Dosages of Guanabenz:


  • 4 mg
  • 8 mg

Dosage Considerations – Should be Given as Follows:


  • Initial dose: 4 mg orally every 12 hours initially; may increase the dose by 4-8 mg/day at 1-2 week intervals
  • The maintenance dose range is typically 4-16 mg orally every 12 hours
  • Not to exceed 32 mg orally every 12 hours

Dosing Considerations

Geriatric patients

  • Adverse CNS effects; may cause bradycardia and orthostatic hypotension; not recommended as routine treatment for hypertension (Beers criteria)
  • Not drug of choice in elderly because of CNS effects
  • 4 mg orally once daily, gradually increase every 1-2weeks

Safety and effectiveness not established in pediatric patients.


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What Are Side Effects Associated with Using Guanabenz?

Side effects of Guanabenz may include:

Less common side effects of Guanabenz include:

  • Weakness
  • Chest pain
  • Fluid retention (edema)
  • Palpitations
  • Anxiety
  • Loss of coordination
  • Depression
  • Itching
  • Rash
  • Breast enlargement in males (gynecomastia)
  • Abdominal pain
  • Constipation
  • Diarrhea
  • Nausea
  • Vomiting
  • Muscle pain
  • Blurred vision
  • Shortness of breath
  • Nasal congestion

Other side effects of Guanabenz include:

  • Rebound hypertension with abrupt discontinuance

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Guanabenz?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Guanabenz has no listed severe interactions with other drugs.
  • Guanabenz has no listed serious interactions with other drugs.
  • Moderate interactions of Guanabenz include:
  • Guanabenz has no listed mild interactions with other drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Guanabenz?


  • This medication contains guanabenz. Do not take Wytensin if you are allergic to guanabenz or any ingredients contained in this drug.
  • Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


  • Hypersensitivity to guanabenz

Effects of Drug Abuse

  • No information is available.

Short-Term Effects

  • See "What Are Side Effects Associated with Using Guanabenz?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Guanabenz?"


Pregnancy and Lactation

  • Use guanabenz during pregnancy with caution if the benefits outweigh the risks. Animal studies show risk and human studies are not available or neither animal nor human studies were done.
  • It is unknown if guanabenz passes into breast milk. Avoid guanabenz use during breastfeeding.


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