Claritin (Clarityne) contains the active ingredient loratadine, which is a type
of medication called a non-sedating antihistamine. It works by preventing the
actions of histamine.
Loratadine (Clarityne) works by blocking your histamine H1 receptors. It doesn't prevent the
actual release of histamine from mast cells, but it does prevent it binding to
the
receptors. This in turn prevents the release of other allergy chemicals and
increased blood supply to the area, and provides relief from the typical
symptoms of hay fever.
Loratadine can also be used to relieve the symptoms of a condition called
chronic idiopathic urticaria. This is a chronic and itchy rash, similar to the nettle
rash, but with no apparent causes. Blocking the actions of the histamine relieves the
itching and reduces the rash associated with these conditions.