Nyquil does not have codeine in it. Codeine is a controlled substance, so individuals must receive a prescription for codeine from a licensed physician. Nyquil is an over-the-counter cough and cold medicine that only contains ingredients that are generally regarded as safe by the U.S. Food and Drug Administration.
Nyquil contains the pain reliever acetaminophen, a cough suppressant called dextromethorphan and an antihistamine known as doxylamine succinate. The medicine also contains FDA-approved dyes and preservatives that help to keep the medicine stable at room temperature until its expiration date. In addition, the medicine contains sodium, potassium, high fructose corn syrup and purified water.