It became the first FDA-approved prescription antihistamine in 1946.

For chronic or especially troublesome outbreaks of hives, your doctor will probably order a course of prescription antihistamines.

He hadn't yet unpacked their toothbrushes and shaving gear, but he'd left a plastic pharmacy bottle, containing a prescription antihistamine, on the counter beside the sink.

Some over-the-counter antihistamines and some prescription antihistamines can cause drowsiness.

Sold over the counter (OTC), they are less expensive than prescription nonsedating antihistamines.

Hives and angioedema often need no medication, but severe cases may require prescription antihistamines, Zantac, or steroid pills.

And a prescription antihistamine, decongestant, nasal steroid or other medication may be indicated to help you cope with your symptoms.

Examples of prescription antihistamines include:

None of the three major prescription antihistamines (Allegra, Claritin, Zyrtec) seems to be consistently more effective than the others.

The drug, used widely for allergies, also contained a prescription antihistamine.