Can i mix allergy medications?

Careful: Some allergy medications such as Benadryl (diphenhydramine) and zyrtec are sedating and together may be too sedating to function. Mixing allergy medications is best prescribed under the supervision of an allergist to avoid side effects. It depends what you are trying to treat, usually one second generation antihistamine is enough to treat nasal allergies. Other medications can be used for other symptoms.