How does NyQuil make you sleepy?
Drowsiness is one of the major side effects of some antihistamines, such as diphenhydramine (Benadryl) and doxylamine succinate (the antihistamine found in Nyquil). And because of their powerful sedating qualities, antihistamines are also the active ingredients found in numerous over-the-counter sleep aids.
While the average dose of Nyquil lasts an average of 4-6 hours, doxylamine can have a slightly wider range of effect. Depending on the person, it can last anywhere from 3 to 8 hours, making it an ideal choice as a night time sedative.
- Common side effects may include:
- headache, sleep problems (insomnia);
- upset stomach, diarrhea or constipation;
- dry eyes, blurred vision, dry mouth or nose;
- mild dizziness or drowsiness, trouble concentrating;
- feeling restless or excited (especially in children); or.
- mild skin rash.
- In this case, elimination could take up to 5 days, whereas among a normative metabolizer, elimination should take between 17 and 33 hours. The bottom line though is that nearly every ingredient within common DayQuil formulations should be out of your system within 48 hours of your last dose.
- Dextromethorphan is a cough suppressant that affects a certain part of the brain, reducing the urge to cough. Decongestants help relieve stuffy nose and ear congestion symptoms. Acetaminophen (APAP) is a non-aspirin pain reliever and fever reducer.
Updated: 2nd October 2019