Before taking clemastine,
tell your doctor and pharmacist if you are allergic to clemastine, other antihistamine medications, any other medications, or any of the ingredients in clemastine tablets or liquid. Ask your doctor or pharmacist or check the package label for a list of the ingredients.
tell your doctor if you are taking monoamine oxidase (MAO) inhibitors such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate). Your doctor may tell you not to take clemastine if you are taking one of these medications.
tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: other medications for colds, hay fever, or allergies; medications for depression or seizures; muscle relaxants; narcotic medications for pain; sedatives; sleeping pills; and tranquilizers. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
tell your doctor if you have or have ever had asthma or lung disease; glaucoma (a condition in which increased pressure in the eye can lead to gradual loss of vision); ulcers; difficulty urinating (due to an enlarged prostate gland); blockage in the passage between the stomach and intestine; blockage in the bladder;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 medication may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
talk to your doctor about the safe use of alcohol while you are taking clemastine. Alcohol can make the side effects of this medication worse.