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 include: anticholinergic medications (., antispasmodics such as belladonna alkaloids, scopolamine), alpha blockers (., doxazosin, prazosin, terazosin), dopamine agonists (., cabergoline, pergolide), metoclopramide, piperazine, drugs for Parkinson's disease (., levodopa and carbidopa, selegiline), certain drugs for high blood pressure (methyldopa, guanethidine, guanadrel, hydralazine). Many drugs besides zuclopenthixol may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, procainamide, quinidine, sotalol, macrolide antibiotics (such as erythromycin), among others. Therefore, before using zuclopenthixol, report all medications you are currently using to your doctor or pharmacist. 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, drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine). Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.