Clemastine (patient information)
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Why this medication is prescribed
Clemastine, an antihistamine, is used to relieve hay fever and allergy symptoms, including itchy skin; hives; sneezing; runny nose; and red, itchy, tearing eyes.
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
How this medication should be used
Clemastine comes in regular and extended-release tablets and liquid to take by mouth. It usually is taken twice a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take clemastine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Do not crush or chew extended-release tablets; swallow them whole.
Speak with your doctor before giving this medication to a child younger than 12 years of age.
Special precautions
Before taking clemastine:
- tell your doctor and pharmacist if you are allergic to clemastine or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially other medications for colds, hay fever, or allergies; medications for depression or seizures; muscle relaxants; narcotics (pain medications); sedatives; sleeping pills; tranquilizers; and vitamins. Do not take clemastine if you have taken an MAO inhibitor [phenelzine (Nardil) or tranylcypromine (Parnate)] in the last two weeks.
- tell your doctor if you have or have ever had asthma or lung disease, diabetes, glaucoma, ulcers, difficulty urinating (due to an enlarged prostate gland), heart disease, high blood pressure, seizures, or an overactive thyroid gland.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking clemastine, call your doctor.
- if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking clemastine.
- you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how this drug affects you.
- remember that alcohol can add to the drowsiness caused by this drug.
What to do if you forget a dose
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Side effects
Minor side effects
Clemastine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- drowsiness
- dry mouth, nose, and throat
- dizziness
- upset stomach
- chest congestion
- headache
Severe side effects
If you experience any of the following symptoms, call your doctor immediately:
- dry mouth
- excitement (especially in children)
- nervousness
- enlargement of pupils in the eye
- increased sensitivity to sunlight
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].
Storage conditions needed for this medication
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of emergency/overdose
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
Other information
Keep all appointments with your doctor.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
Brand names
- Anti-Hist®-1
- Dayhist®-1
- Tavist®
- Tavist® Allergy (formerly Tavist-1®)
- Tavist® Syrup