Xyzal (levocetirizine) and Zyrtec (cetirizine) are over-the-counter (OTC) allergy medications. Learn about their key ...

Taking too much antihistamine can lead to adverse side effects and a potential antihistamine overdose. Signs may include fast heart rate, fever, and dilated pupils. People should follow the dosage ...

Medically reviewed by Corinne Savides Happel, MD If you're pregnant, you may wonder if it's safe to use antihistamines. An estimated 10% to 15% of pregnant people do use these drugs to treat allergic ...