Clemastine fumarate comes in the form of a tablet, and is used to relieve allergy symptoms such as sneezing and the common cold. This medicine is also “indicated for the relief of mild, uncomplicated allergic skin manifestations of urticaria and angioedema.”(rxlist.com) Bear in mind that drowsiness is the most common side effect associated with the treatment in question. And considering the fact that it occurs relatively frequently, discontinuing therapy is recommended in some cases. You should also keep the following side effects in mind before taking Clemastine fumarate, or any other drug that belongs to the class of antihistamines for that matter. The side effects that can occur include dryness of mouth, headache, Hemolytic anemia, hysteria, nausea, and vomiting. According to rxlist.com, “antihistamines should be used with considerable caution in patients with: narrow angle glaucoma, stenosing peptic ulcer, pyloroduo-denal obstruction, symptomatic prostatic hypertrophy, and bladder neck obstruction.” Remember that children under the age of 12 years should not use Clemastine fumarate as it is still not clear whether it is safe for them or not. And if you are pregnant, you need to consult your doctor before taking this drug. On a side note, you should take Clemastine fumarate with food or milk if stomach upset occurs.