Why ranitidine is not used as anti-allergic drug ?

Sometimes it is: Ranitidine is an h2 type of antihistamine. Most h2 receptors are in the stomach and therefore ranitidine is effective in acid suppression for stomach acid reflux. However, there are h2 receptors around blood vessels so ranitidine is sometimes used in treatment of hives and severe allergic reactions like anaphylaxis. H1 antihistamines are best for allergic reactions.