Health Guide

Clemastine (By mouth)

Clemastine (kle-MAS-teen)

Treats allergy symptoms (hay fever).

Brand Name(s):

Good Sense Dayhist Allergy, Tavist Allergy, TopCare Dayhist Allergy

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to clemastine or any other antihistamine medicines. Do not use it if you are breastfeeding, you have a lung disorder such as asthma, or you are using a monoamine oxidase inhibitor (MAOI) such as isocarboxazid, phenelzine, selegiline, or tranylcypromine.

How to Use This Medicine:

Tablet, Liquid

  • You may take this medicine with food to prevent stomach upset.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Keep this medicine at room temperature, away from heat, direct light, and moisture. Do not freeze the oral liquid.

Drugs and Foods to Avoid:

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

  • Some medicines and foods can affect how clemastine works. Tell your doctor if you are using any of the following:
    • Antidepressants
    • Narcotic pain killers
    • Other antihistamines
    • Sleeping pills
    • Tranquilizers
  • Do not drink alcohol while you are taking this medicine.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding.
  • Tell your doctor if you have glaucoma, an ulcer, or problems with your bladder or prostate.
  • This medicine should not be given to children under 12 years of age unless ordered by a doctor.
  • Side effects of this medicine may be more likely in children and older adults. Clemastine syrup contains alcohol.
  • This medicine may make you drowsy. Be careful when you drive or operate dangerous machinery.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

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

  • Facial flushing
  • Fainting
  • Severe drowsiness
  • Trouble breathing

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

  • Clumsiness, mild drowsiness, or dizziness
  • Dry mouth or throat, or thickening of mucus
  • Nausea, vomiting, diarrhea, constipation
  • Urinating often, trouble urinating

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: 8/2/2019
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