Claritin can treat post-nasal drip caused by sinusitis and viral infections, according to WebMD. Post-nasal drips are caused by a variety of conditions, and the method of treatment depends on the underlying cause of the post-nasal drip.
Methods of post-nasal drip treatment include antibiotics, antihistamines, decongestants and thinning the mucus, explains WebMD. In addition, flushing out excess mucus and irritants with a saline nasal spray can help relive a post-nasal drip. Older antihistamines, such as Benadryl, can actually thicken mucus as a result of drying it. Newer antihistamines, such as Claritin, Allegra and Zyrtec may be better options and are less likely to cause drowsiness.