According to WebMD, hydroxyzine HCl is an oral antihistamine used to treat itching caused by allergic reactions. The medicine works by blocking the production of histamine the body makes in response to an allergic reaction. The medicine is also used short term to treat anxiety, and it is sometimes given to patients before surgery to help them relax.
If used for an allergic reaction, WebMD states that the medicine is normally taken three or four times a day, with or without food. However, one should always follow his doctor's instructions because oftentimes the amount of hydroxyzine HCl taken in each dose is determined by weight, age and state of health at the time.
Common side effects associated with the drug include drowsiness, dry mouth, constipation and blurred vision. However, a large majority of people have no adverse reactions when taking the medicine. If one begins to experience symptoms such as restlessness, hallucinations, confusion, difficulty urinating and a fast or irregular heartbeat, WebMD recommends contacting a doctor as soon as possible. WebMD also states not to use this drug with other antihistamines applied to the skin. If an overdose is suspected, contact a poison control center or the emergency room immediately.