Claritin contains the drug loratadine, while Claritin-D adds the decongestant pseudoephedrine, according to Drugs.com. Loratadine is an antihistamine that blocks the effects of histamine, such as sneezing, watery eyes and a runny nose. Pseudoephedrine shrinks the blood vessels to relieve swelling that causes congestion.
Some forms of Claritin are self-dissolving in the mouth; however, users should swallow Claritin-D tablets whole and not chew them. They should also swallow the nondissolving form of Claritin whole, warns Drugs.com. It is essential that users read and follow label directions exactly for the type of Claritin they are using.
While Claritin is available as a liquid for children, parents should not give it to a child under 2. They should only give the medication to children under 6 on the advice of a physician, indicates Drugs.com.
Common side effects of Claritin include headache, stomach pain, dry mouth and feeling tired or hyperactive. Claritin-D has similar side effects, but with the addition of pseudoephedrine, it may also cause nervous system side effects, affect blood pressure and cause cardiac problems.
While loratadine is an antihistamine, it does not stop hives or anaphylactic shock, according to WebMD. Patients with a prescription for ephedrine for anaphylaxis should carry their injector pen and not depend on loratadine for treatment.