Loratadine 10 milligram tablets are the generic of Claritin, an antihistamine used to treat unpleasant allergy symptoms, such as sneezing, itchy eyes and a runny nose, states RxList. One of the most common side effects of Loratadine tablets is difficulty falling or staying asleep, notes MedlinePlus.
Drowsiness when taking Loratadine may be a symptom of overdose, along with a fast or pounding heartbeat, irregular body movements and headache, according to MedlinePlus.
Antihistamines work by blocking histamine in the body, which causes allergic reactions and symptoms. Loratadine is available in antihistamine form or in combination with pseudoephedrine, as stated by MedlinePlus.