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: antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray), ketoconazole, levoketoconazole.

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).

Antihistamines are ingredients found in many nonprescription products and in some combination prescription medications. Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may also contain an antihistamine or other ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

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