How long does Nyquil last? Will it last all night?
All versions of Nyquil (e.g. Cold & Flu, Severe) last around four to six hours per dose.
The most common version of Nyquil is Nyquil Cold & Flu. It contains the following ingredients:
- Acetaminophen: Pain reliever and fever reducer
- Dextromethorphan: Cough suppressant
- Doxylamine: Sedating antihistamine
Each dose of Nyquil Cold & Flu will begin to work about 15-30 minutes. However, the sedating ingredient in the medication (doxylamine) reaches peak blood around 2-3 hours after administration. This is why the onset of sedation may be somewhat slow to take effect.
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. Any longer, and there would be a high chance of morning grogginess.
Below, we list the other common versions of Nyquil:
Nyquil Severe contains the following ingredients:
Nyquil severe adds the ingredient phenylephrine, a nasal decongestant. Nyquil severe also lasts around 4-6 hours per dose. Some find Nyquil Severe not quite as sedating as Nyquil & Flu because phenylephrine has a mild stimulant effect.