Claritin treats symptoms associated with seasonal allergies, such as sneezing, a runny nose and watery eyes, according to Drugs.com. Claritin can also treat hives, inflammation of the nose due to allergies and allergic conjunctivitis, explains WebMD.
Claritin is an antihistamine that works by blocking the body's production of histamine, states Drugs.com. During an allergic reaction, the body produces histamine, which can cause watery eyes, sneezing and other symptoms common during allergic reactions. Allergy sufferers usually take it once a day and should not chew or crush the tablets prior to taking them.
Common side effects of Claritin, according to Drugs.com, are headache, nervousness, drowsiness, dry mouth and red eyes. Claritin can sometimes cause nose bleeds, a sore throat or hoarseness as well. These side effects are generally mild, but if a person experiences side effects such as seizures, jaundice, a rapid or uneven heartbeat or a feeling of faintness, she should seek immediate medical attention.
Claritin may also interact with other drugs or vitamins, according to Drugs.com. Some known interactions include a very similar medication called desloratadine, which WebMD recommends not using while taking Claritin. It may also interfere with certain laboratory tests, such as allergy tests, so anyone having such a test should inform the prescribing doctor.