How Long Does Nyquil Last: A Comprehensive Guide

how long does nyquil last

It is important to know how long does NyQuil last in our systems as it may seem a comfortable OTC (Over The Counter) option when we are suffering from cough, cold, allergies or sore throat. Being an over the counter effective medicine, it may seem to be flawless. However, it is not so. It does have some side effects. This article is all about NyQuil: its composition, dosage, effectiveness, side effects and most importantly how long it stays in our bodies; so that next time when you take a dose of NyQuil, you be prepared for a NyQuil hangover the following day. 

If we talk about an approximate figure of the time in which NyQuil lasts is around 6 hours. After consuming Nyquil it takes 6 hours to stay in your body. Don’t ever take NyQuil in a gap of a short period of time than 6 hours. 

Nyquil contains doxylamine which is the main ingredient of some NyQuil tablets. This lasts for around 8 hours in the human body. You may feel dizziness in this span of time because of the nature of doxylamine. 

If we include here medical science then the half life time span of doxylamine is 10 hours. It means it can stay and dissolve in your body in around  20 hours. All of these scenarios make the time frame of NyQuil a little complicated.

What Nyquil Is?

NyQuil is a medicine from the reputed brand Procter & Gamble, widely used to get relief from the symptoms of cold and flu. Symptoms of cold and flu include runny nose, sneezing, cough, sore throat, headache and body aches etc.  This is an OTC medicine available in both liquid and pill form, liquid version is however more popular. 

Ingredients of Nyquil

Active ingredients in Nyquil are 

  1. Acetaminophen
  2. Dextromethorphan, and 
  3. Doxylamine Succinate.
  4. Sodium citrate
  5. Citric acid
  6. Propylene glycol
  7. Polyethylene glycol 

Acetaminophen is an antipyretic and a pain reliever. An Antipyretic is a drug that lowers down the body temperature thereby reducing fever. 

Dextromethorphan is used to suppress cough. 

Doxylamine Succinate is an antihistamine which treats allergies by blocking histamines. Going by the list of ingredients of Nyquil, it becomes obvious that it provides relief from cough, fever, headache, body aches and allergies. 

Citric acid has the property of acting as a flu killer and it is present in the NyQuil in a very small amount. Nyquil is for swallowing but citric acid works as a flu killer when it goes into the body by spraying in the nose. That’s why it exists in the NyQuil but in a small fraction. 

Polyethylene glycol and propylene glycol are used to maintain the texture of NyQuil. Nyquil has the density of water and honey and these two ingredients try to balance it. Although many experts prefer it in a spray. 

When to take Nyquil?

When you are stuck with a cold and the flu, all you want is to sleep. But sleep does not come that easy when you have a congested chest & nose, fever, runny nose and headache. This is when you lay your hands on NyQuil despite knowing that you are going to get a NyQuil hangover the following day. It starts working within 10 minutes to half an hour after its first dose. Nyquil gives you a sound sleep when you are unable to sleep because of cold and flu. Symptoms of cold and flu are relieved and you get a good night’s sleep. 

But when you wake up the next day, you will be up with heavy eyes and a foggy feeling. It would feel like you are walking in molasses all around. Vision gets hazy. This is going to happen irrespective of the duration of sleep. You will be under the influence of NyQuil if you get up after six hours or eight hours or even after ten hours. In such a situation, one likes to try caffeine. But even caffeine does not work. 

It is advised to take NyQuil after every six hours which gives a false indication that NyQuil does not last for more than six hours in our systems; but its side effects can be seen even after ten hours of its dose. 

Nyquil doses:

If you are an adult you can take 30ml in every six hours if it is in liquid form. 

If you give this to your children then it becomes very important to ask the doctor. 

Recommendations of a doctor about doses of NyQuil are preferred.

Following are the most common side effects of NyQuil:

  1. Difficulty in NyQuil
  2. Dizziness
  3. Drowsiness
  4. Fatigue
  5. Weakness
  6. Anxiety
  7. Excitability
  8. Loss of appetite
  9. Diarrhea or constipation
  10. Upset stomach
  11. Nausea
  12. Vomiting
  13. Hangover

How long does NyQuil last?

Let’s learn about the half lives of various ingredients of NyQuil to get an idea about how long it stays in our bodies.

Acetaminophen: Half of it stays in the body of a healthy adult for around 2-3 hours. It gets flushed out entirely from the system after 22 hours.

Dextromethorphan: Half life of dextromethorphan is 3-6 hours and it takes 11-33 hours for complete elimination from the body.

Doxylamine Succinate: Fifty percent of Doxylamine Succinate gets removed after 10 hours and the whole of it takes around 2.25 days to clear up. 

So it is clear that a substantial part of NyQuil is eliminated from the body after 10 hours of its consumption. Doxylamine Succinate, which induces sleep, is the last one to get removed from the systemic circulations. 

However, Nyquil stays in bodies of different individuals for different durations depending upon following factors:

  1. Age
  2. Metabolism
  3. Body Mass
  4. Amount and frequency of dosage
  5. Co-administration of other medicines

How long does Nyquil last in your system?

As it is told above in the article that it takes 6 hours to affect your system to release symptoms like drowsiness and sleepiness. It varies from person to person. In some people, drowsiness comes after 8 hours.

If we conclude it in short then we would say you can do your work and other activities after around 10 hours. Sometimes it can be difficult to do your daily activities because of sleepiness effect of NyQuil.

If you face this situation, just wait and rest to your body. It takes only 10 hours after that you would feel good and active.

When Nyquil expires?

Although whenever you go and purchase NyQuil no matter its liquid form or tablets , you see the expiry date on the label. Kindly check this date before using NyQuil .

Don’t use expired NyQuil because it loses its effectiveness once it gets expired. Some factors like humidity and other environmental factors reduce the expiry date of NyQuil.

Be extra aware while purchasing NyQuil and be sure it is not expired.


No matter how long Nyquil stays, it is for sure that you will start your day with heavy eyes and a little blurry vision. It is very important to give yourself at least eight hours of sleep before starting the day. It is highly recommended not to drive or operate heavy machinery for at least 8 hours after administration. 

One should be absolutely fine after 10 hours and can start day to day activities. If the hangover gets worse and you feel drowsy, heavy and confused even after 10-12 hours, it is advisable to take medical assistance. 

Frequently asked questions:

Q1. How long does NyQuil stay in your system?

Ans. It normally stays around 6 hours but because of the nature of its ingredients it may last 10-12 hours.

Q2. What is a NyQuil hangover?

Ans. Nyquil hangover is one of the symptoms of taking NyQuil. In this you may feel sleepiness after taking NyQuil . 

Q3. How long does it take for NyQuil to wear off?

Ans. Normally it takes 6 hours but sometimes it exceeds 8 hours.

Q4. Does NyQuil make you drowsy the next day?

Ans. Yes, it may cause sleepiness after sometime when you take it. The ingredients and sedatives have the property of drowsiness. 

Q5. How long does NyQuil make you drowsy?

Ans. It varies from person to person. Some may feel sleepiness after 30 minutes and some after a long time. 

Q6. How long does NyQuil make you sleep?

Ans. Some people feel it within 30 minutes and some feel it after hours. But the overall effect lasts upto 6 hours.

Q7. How long does NyQuil severe last?

Ans. Upto 6 hours. The ingredient doxylamine has 10 hours half life time and it dissolves in the human body upto 20 hours. 

Q8. Does NyQuil make you drowsy the next day? 

Ans. Yes it may. Because of the nature of ingredients and sedatives, you can feel drowsiness after taking NyQuil.

Q9. How long does NyQuil take to kick in?

Ans. It starts working very fastly within 30 minutes. You need to spray it after every 6 hours. 

Q10. How to flush NyQuil out of your system?

Ans. Drinking water can help you here to flush NyQuil out of your system. 

Q11. How much NyQuil is one dose?

Ans. For adults, 30ml in every 6 hours and for children kindly take doctor’s prescription.

Q12. Does NyQuil make you tired?

Ans. Drowsiness is the main effect after taking NyQuil. You can feel tired in drowsiness. It helps your body to relieve the fever and flu. 

Q13. Does NyQuil have alcohol in it?

Ans. Nyquil liquid may contain alcohol but NyQuil LiquiCaps don’t contain alcohol.

Q14. Does NyQuil have ibuprofen?

Ans. It’s a combination of ibuprofen and pseudoephedrine.

Q15. Can I take ibuprofen and Nyquil two?

Ans. These two are not react with each other after consuming but it’s superfluous because Nyquil itself contains ibuprofen.

Q16. How long does Nyquil take to work?

Ans. You should take dose of NyQuil after every six hours. Although it may start working within 30 minutes after taking.

Q17. How long does NyQuil drowsiness last?

Ans. The drowsiness that comes because of the nature of ingredients lasts upto 8 hours.

Q18. How many hours does NyQuil last?

Ans. You should consume Nyquil dose after every six hours that means Nyquil lasts around six hours.


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