What are the precautions for clemastine (Dayhist Allergy or Tavist)?

Stacy Wiegman, PharmD
Pharmacy Specialist

There are several precautions you should discuss with your doctor and/or pharmacist before taking clemastine (Dayhist Allergy or Tavist).

  • Tell your doctor if you have allergies to clemastine or other antihistamines (such as diphenhydramine or chlorpheniramine).
  • Do not take any monoamine oxidase inhibitors (older antidepressants).
  • Tell your doctor and pharmacist every other nonprescription substance (including vitamins or aspirin) and prescription drug you are taking.
  • Talk to your doctor before taking clemastine if you have a history of asthma or lung disease, glaucoma, ulcers, problems urinating, blockage in your gastrointestinal tract or bladder, heart disease, high blood pressure, seizures or an overactive thyroid.
  • If you plan to become pregnant or already are, talk to your doctor.
  • Tell your doctor or dentist that you are taking clemastine prior to any procedure or surgery.

Clemastine may cause one or more side effects. More common and less serious side effects include the following:

  • Chest congestion
  • Drowsiness and/or dizziness
  • Dry mouth, nose and throat
  • Headaches
  • Lack of coordination
  • Nausea
  • Nervousness or excitement (children may be especially affected)

Other side effects of clemastine can be serious. Call your doctor if you experience any of these symptoms:

  • An irregular, fast or pounding heartbeat
  • Changes in your vision
  • Difficulty breathing or swallowing
  • Itching, hives, redness or rash
  • Problems urinating

Call 911 for difficulty breathing or swelling of the mouth, lips or tongue.

Take a missed dose of clemastine when you remember it, unless it is nearly time for the next dose. If it is close to the time of your next dose, then skip the missed dose and continue the proper dosage at the regular time.

Do not double-up on doses if you miss one since this may cause more severe side effects. Call your local poison control center at 1-800-222-1222 if someone takes too much. Also, call your doctor and/or pharmacist to help you determine what to do. If the person who has overdosed is not breathing or collapsed, call 911 for emergency services.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.