Claritin - loratadine
- is a long-acting antihistamine. Histamine is a chemical that causes
many of the signs that are part of allergic reactions, for example,
swelling of tissues. Histamine is released from histamine-storing cells
(mast cells) and attaches to other cells that have receptors for
histamine. The attachment of the histamine to the receptors causes the
cell to be "activated," releasing other chemicals which produce the
effects that we associate with allergy. Loratadine blocks one type of
receptor for histamine (the H1 receptor) and thus prevents activation of
cells by histamine. Unlike most other antihistamines, loratadine does
not enter the brain from the blood and, therefore, does not cause
drowsiness.
SIDE EFFECTS: In studies in which loratadine was compared to a
placebo (an inactive tablet which was made to look like loratadine), the
rates of side effects with loratadine was no greater than that of the
placebo. The most common complaints were headache, tiredness, and dry
mouth.
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