Herbal supplements, including St. John's wort, ginseng and nutmeg. Over-the-counter cough and cold medications containing dextromethorphan (Delsym) Anti-nausea medications such as granisetron (Sancuso, Sustol), metoclopramide (Reglan), droperidol (Inapsine) and ondansetron (Zofran, Zuplenz)