Benadryl is a medication that is commonly used to treat allergies. It works by blocking the action of histamine, a substance produced by the body in response to an allergen. While Benadryl is generally considered safe, it can cause some side effects, including drowsiness, dry mouth, and dizziness. In rare cases, it may also lead to liver or kidney damage. However, most people taking Benadryl do not experience severe side effects. If you are concerned about the potential risks, you should speak to your doctor before taking any medication.