If you are taking this medication under your doctor's direction, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.Before using this product, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: "blood thinners" (such as warfarin), isoniazid, MAO inhibitors (isocarboxazid, linezolid, moclobemide, phenelzine, procarbazine, rasagiline, selegiline, tranylcypromine).Tell your doctor or pharmacist if you are taking other products that cause drowsiness, including alcohol, other antihistamines, drugs for sleep or anxiety (such as alprazolam, diazepam, zolpidem), muscle relaxants, and narcotic pain relievers (such as codeine).Acetaminophen and antihistamines are ingredients found in many nonprescription products and in some combination prescription medications. Check the labels on all your medicines (especially pain relievers, fever reducers, and cough-and-cold products) because they may also contain acetaminophen or an antihistamine. Ask your pharmacist about using those products safely. (See also adult maximum daily dose information in Side Effects section.)This medication may interfere with certain medical/laboratory tests (such as urine 5-HIAA, allergy skin tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.