How Long Does NyQuil Last? [Answered]



NyQuil can usually last in your body for up to 3-5 hours. However, NyQuil can also last up to 8 hours in some rare cases.

So, if you are taking the NyQuil dose, then it is safe to say that the medicine will last in your body for around 3-5 hours after taking it.

NyQuil Ingredients: What Do They Do?

The main ingredient of NyQuil is Diphenhydramine which is an antihistamine drug. It can reduce fever and provide consumers relief from all the common cold and flu symptoms.

The second ingredient of NyQuil is Dextromethorphan Hydrobromide or DXM, which will help you to control coughs that produce mucus. Another main ingredient is Acetaminophen (also known as Paracetamol) which can reduce headaches and body aches.

Also, NyQuil contains an anti-nausea medication. NDC code of Nyquil is 00603-0012-10 with 30 dosages per container.

NyQuil Dosage: How Many Tablets Per Day?

The recommended dosage is one or two teaspoonfuls every 4 hours or as needed. For best results, take NyQuil before bedtime. Or follow your doctor.

NyQuil should not be taken more than four times a day and never take more than six doses in 24 hours…When taking NyQuil one time the whole night, you can sleep well all night long due to its low level of Diphenhydramine.

How Long Does NyQuil Make You Sleep?

NyQuil can fall you asleep for 6-8 hours. However, we can not say that NyQuil makes you sleep every time.

Does NyQuil Make You Drowsy the Next Day?

There is a lot of debate about NyQuil and its side effects (if any). Some users say that it makes them very sleepy the next day.

Unlike Vicks Vaporin, NyQuil does not contain Tetrahydrocannabinol or THC, which causes drowsiness.

What are NyQuil Side Effects?

Special attention should be taken to pregnant and breastfeeding women. It is not recommended for nursing babies and young children. Also, those patients who are allergic to NyQuil ingredients should avoid taking it!

NyQuil’s side effects can include vomiting, dryness of mouth or throat, drowsiness, nervousness or restlessness, headache, Runny Nose, and stomach upset.

Does NyQuil Addictive?

Yes, if you start to take NyQuil before every sleep, then there are chances that you will become dependent on NyQuil which can lead to addiction.

NyQuil is a medicine that we recommend you to take in case of cold and flu symptoms only! It’s not recommended to use it on a regular basis or for sleeping purposes.

What are the Factors that Determine the Long Lasting of NyQuil in your System?

There are some factors that will cause NyQuil to affect long-lasting and vice versa. So here are the factors.

Age and Sex:

Age and sex both cause to vary the effect of NyQuil. It also causes different periods for NyQuil to be long-lasting in your body. For older adults, it requires more dosage per day.

Food Intake:

Eating a full meal before taking NyQuil will slow down the absorption of Diphenhydramine into your bloodstream. So, it will make the medicine last long in your system.


When NyQuil is given in a cold place, then its duration of action changes. So, you have to take more dosage if you live in a cold area.

Body Fat Percentage:

The body fat percentage is very high in women than in men. Thus, it can lead to a high concentration of NyQuil in their blood after taking medicine, making the medicine last longer for them.


NyQuil dosage per day is also important if you want short or long-lasting effects. The higher the dosage, the more concentration it will have in the blood, so the drug will last longer.

Glutathione levels:

Antioxidant glutathione can affect the elimination of Nyquil in your system. It is higher in women than men.

Health Issues:

Some health issues like kidney or liver problems will also cause the NyQuil drug’s long-lasting effects. So, you have to consult with your doctor if you are having any kind of kidney or liver problem.


Please keep in mind that this is not professional medical advice, and it should not be treated as one! Our main purpose at How Long Does Last is to spread valuable information about the shelf life of everything.

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