Daily OTC Pearl: ZzzQuil

Diphenhydramine is an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold.

Indication: Diphenhydramine is an antihistamine used to relieve symptoms of allergyhay fever, and the common cold.


  • This medication works by blocking a certain natural substance (histamine) that the body makes during an allergic reaction. Its drying effects on such symptoms as watery eyes and runny nose are caused by blocking acetylcholine.
  • Take the tablet, capsule, or liquid form by mouth with or without food. Measure liquid forms of this medication using a special measuring cup or spoon.
  • Adverse effects can include drowsiness, dizzinessconstipationstomach upset, blurred vision, or dry mouth, nose or throat.
  • To relieve dry mouth, suck hard candy or ice chips, chew gum, drink water, or use a saliva substitute.
  • Before taking diphenhydramine, pharmacists should know whether the patient is allergic to ZzzQuil or dimenhydrinate. This product may contain inactive ingredients, which can cause allergic reactions or other problems