what is in nyquil that makes you sleepy

Most formulations of NyQuil contain three active ingredients: doxylamine succinate, dextromethorphan, and acetaminophen. Doxylamine succinate is an antihistamine that is included in NyQuil to treat nasal symptoms, such as sneezing or a runny nose. This medication has the potential to cause drowsiness. Dextromethorphan is a cough suppressant that is also included in NyQuil to relieve coughing. Acetaminophen is a common pain reliever that is included in NyQuil to relieve discomfort from headaches and sore throats. Acetaminophen is not known to cause drowsiness. NyQuil usually triggers sleepiness approximately half an hour after a person takes the medication. The duration and quality of sleep can vary. It is important to note that while NyQuil can help with sleep, it is not suitable for use as a general sleeping aid.