See also Warning section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are: ketoconazole, levoketoconazole.

Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or other antihistamines (such as cetirizine, diphenhydramine).

The ingredients in this product are available in many prescription and nonprescription products. Check the labels on all your medicines (such as pain/fever drugs, diet aids, or cough-and-cold/allergy products) because they may contain the same or similar ingredients. Using these drugs along with this product could increase side effects (such as fast heartbeat, increased blood pressure, or drowsiness). Ask your pharmacist about using those products safely.

Do not use with any other antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray) because increased side effects may occur.

This medication may interfere with certain lab tests (such as urine drug screening tests, urine 5-HIAA, allergy skin test), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.