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Guanfacine ER

Common Brand Names: Intuniv

Side Effects & Precautions

Medically reviewed by Jessica Swirble, PharmD
Last updated on 7/10/2024

Drug Information | Side Effects | Use & Dosage | Request a Prescription

What are the side effects of extended-release guanfacine?

The use of extended-release guanfacine can lead to various side effects in some individuals.

Common mild side effects of extended-release guanfacine use include:

  • Drowsiness
  • Fatigue or weakness
  • Irritability
  • Headache
  • Dizziness
  • Dry mouth
  • Constipation
  • Stomach pain
  • Decreased appetite
  • Decreased libido
  • Insomnia

More severe side effects include:

  • Hypotension (low blood pressure)
  • Bradycardia (slow heart rate)
  • Fainting
  • Mood changes or depression
  • Severe allergic reactions (rash, itching, swelling)

If you experience any severe or concerning side effects while taking extended-release guanfacine, contact your healthcare provider right away.

What should I tell my healthcare provider before using extended-release guanfacine?

Inform your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with extended-release guanfacine. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with guanfacine.

Tell your provider if you are taking these medications or supplements:

  • Other ADHD medications
  • Antihistamines
  • Blood pressure medications
  • Heart medications
  • Sedatives or tranquilizers
  • Antidepressants
  • Anti-anxiety medication
  • Certain seizure medications
  • HIV medication
  • Opioid pain medications
  • Antibiotics
  • Antifungals
  • Cyclosporine
  • Tizanidine

You should also mention medical conditions such as:

  • Heart problems
  • Liver or kidney disease
  • Low blood pressure
  • Recent stroke or heart attack
  • Recent or upcoming surgery (including dental surgery)
  • History of fainting
  • Liver or kidney disease

If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential risks and benefits of using guanfacine with your healthcare provider.

Are there any other special instructions I should follow?

Take extended-release guanfacine exactly as prescribed by your healthcare provider. Do not exceed the recommended dose or duration of treatment.

Extended-release guanfacine can cause drowsiness or dizziness. Do not drive or operate machinery until you know how this medication affects you.

Complete the full course of treatment, even if you feel better, to ensure the medication's effectiveness in managing your condition.

What should I do in case of an overdose?

In case of an extended-release guanfacine overdose, seek medical attention immediately. Symptoms of overdose may include severe drowsiness, dizziness, slow heart rate, and low blood pressure. If you suspect an overdose, contact the poison control helpline at 1-800-222-1222 or call emergency services.