Does Nyquil Make You Sleepy? 11 Things To Know

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Medically reviewed by, Russell Braun RPH

You can tell a cold is coming on and you don’t have time for it. Determined to not let it get you down, you decide to swing by the pharmacy to grab something that will pull you out of the grasp of a cold. All the products look the same…but wait there is NyQuil. You know that brand, but start to wonder, will NyQuil make you sleepy?

NyQuil is a brand name medication that is used for cold and flu symptom relief. It is sold over the counter and many people buy this product without any advice from their doctor or pharmacist. That is where the trouble can begin.

1. What Is In NyQuil?

NyQuil has three main ingredients. Those ingredients are a pain reliever/fever reducer, antihistamine and cough suppressant. Most NyQuil products are liquid and the doses shown below are based on two tablespoons or 30ml. A few are not liquid and the amounts shown would be contained in two caplets.

NyQuil™ Cold & Flu Nighttime Relief Liquid
Basic NyQuil

Pain reliver / fever reducer

  • Acetaminophen 650mg

Acetaminophen is found in Tylenol and many other OTC products. It is an effective pain reliever and fever reducer. It is important to not take multiple products containing acetaminophen. To much can be toxic to your liver.


  • Doxylamine 12.5mg

Doxylamine is an antihistamine that induces drowsiness, therefore inducing sleep. While sleep is important especially when sick, antihistamines may have unwanted side effects for many people. In fact, sleepfoundation.org does not recommend the use of antihistamines for insomnia.

Cough suppressant

  • Dextromethorphan 20mg

Dextromethorphan is a cough suppressant. It works by suppressing the cough reflex centers in the brain. While some cold and flu patients may have a cough, not all do. If cough is not a problem then taking dextromethorphan is not going to provide a major benefit.

2. Not All NyQuil Is The Same

The confusing thing about over the counter products is what the heck is in them. NyQuil is no different. A word or two added to the bottle may result in more active ingredients thrown into the mix. That could mean more potential for side effects to you.

The table below shows how many different types of NyQuil that are available.

ProductDosage FormIngredients
NyQuil Cold & FluLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg
NyQuil Severe Cold & FluLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg
Phenylephrine 10mg
NyQuil Severe Cold & FluCapletsAcetaminophen 325mg / caplet
Doxylamine 6.25mg / caplet
Dextromethorphan 10mg / caplet
Phenylephrine 5mg / caplet
NyQuil Cough DM & CongestionLiquidDoxylamine 12.5mg
Dextromethorphan 30mg
Phenylephrine 10mg
NyQuil Severe Cold & Flu HoneyLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg
NyQuil Severe Cold & Flu VapocoolLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg
Phenylephrine 10mg
Vicks vapors
NyQuil HBP Cold & FluLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg
NyQuil Alcohol Free Cold & FluLiquidAcetaminophen 650mg
Doxylamine 12.5mg
Dextromethorphan 20mg

As you can see there is one additional active ingredient (phenylephrine) found in some NyQuil products. NyQuil cough and congestion is also different because it does not contain acetaminophen. Finally, a few products have other inactive ingredients such as honey, vapors or is free from alcohol.


  • Phenylephrine

Decongestants like phenylephrine cause constriction of blood vessels. This helps to relieve stuffy nose which is often a problem with colds and flu. It is important to remember that blood vessel constriction can also raise blood pressure. Therefore, people with high blood pressure may want to avoid using this ingredient.

3. What Is NyQuil Used For?

As the name implies NyQuil is used for cold and flu symptoms. More specifically, Vicks the manufacturer states the uses listed below on the FDA approved label. Keep in mind that NyQuil is only to be used on a temporary basis for these conditions.

  1. Cough from minor throat irritations
  2. Headache
  3. Sore throat
  4. Aches and pains from cold & flu
  5. Fever
  6. Runny nose

NyQuil is best when used at night or when you can rest. This is due to the fact that NyQuil will make you sleepy. Consequently, it may also cause you to be unstable on your feet.

If you need to be alert and on the go, then NyQuil is probably not the best option. That is why Vicks also makes a product called Dayquil. It does not contain the antihistamine ingredient and has a decongestant that can lead to increased stimulation.

Finally, it is important to remember NyQuil is not a cure for cold and flu. Rather it is just helping treat the symptoms.

4. Over The Counter Combination Medications

As noted above, NyQuil is a combination medication. That means it has more than one active ingredient. Most of the time people think more is better when self medicating with over the counter medications. However, this can also open the door for more side effects.

Keep these things in mind before you grab a combination medicine like NyQuil.

  1. Fever is the bodies way of fighting off bacteria and viruses. Raising your body temperature slows down the growth of these microbes. Unless a fever reaches a dangerous level (risk of having seizures) you probably don’t want to break it.
  2. Cough is a natural reflex that is clearing the airway of mucus and phlegm. If you suppress that cough you might be setting yourself up for a build up of mucus in the airways.
  3. Sleeping is a good idea when you are sick. However, antihistamines may help you fall asleep but they do not provide good deep sleep. This plus the side effect risk, especially in older adults is not a good trade off.

5. When Should You Take NyQuil?

If you really feel like you need to suppress fever, cough and get to sleep then NyQuil is a good option for you. However, there are generics of NyQuil with the same ingredients, but cost less. The table below is just one example of this.

Vicks NyQuil Cough, Cold & Flu Nighttime Relief, 48 LiquiCaps - #1 Pharmacist Recommended, Nighttime Sore Throat, Fever, a...Amazon Basic Care Nite Time Cold Flu Relief Softgels, Pain Reliever, Fever Reducer, Cough Suppressant Antihistamine, 48 Count
48 caplets48 caplets
Cost: $16.88*$9.38*

*Prices subject to change.

On the other hand, you could also look for products that only contain one ingredient. This allows you to actually treat the symptoms that are a problem.

Therefore if you have a high fever, treat it. If cough is causing pain then suppress it. If you absolutely can’t fall asleep, then use something to help you. The moral of the story is treat the symptom that is really bothering you. It isn’t worth the risk of taking a bunch of ingredients for symptoms you don’t have!

6. How Long Does NyQuil Make You Sleep?

The doxylamine in NyQuil is the primary reason you get sleepy. It blocks histamine type 1 (H1) receptors in your brain and central nervous system. As a result, you feel sleepy.

Ironically, blocking histamine type 1 receptors can also cause strange dreams that may wake you after you do fall asleep.

The duration of sleep is usually based on how long the doxylamine is in your system. If you take the normal two tablespoon dose you should expect NyQuil to last four to six hours. However, you may sleep longer due to your body trying to fight off the cold.

7. How Can I Fall Asleep Instantly?

NyQuil will not make you fall asleep instantly. However, most people do fall asleep within 30 minutes of taking their dose. A good trick is to drink some water with the NyQuil to help it get absorbed a little quicker. Subsequently, it should take action faster as well.

Some other ways to help you get to sleep fast include:

  • Avoid caffeine or any medication with a decongestant in it.
  • Take a warm shower.
  • Put down any phones, tablets or laptops and put them on do not disturb.
  • Turn off the television
  • Close your eyes and take deep breaths in through your nose for at least 4 seconds, hold it for 5 seconds and exhale through your mouth over 6 seconds.

8. Is It Bad To Take NyQuil To Sleep?

If you have trouble sleeping due to a cold or flu then taking NyQuil may be a good way to get to sleep. However, it is not supposed to be used repeatedly for that purpose. Trouble falling to sleep that persists and is not due to a cold is called insomnia. NyQuil is NOT a treatment option for insomnia!


The dextromethorphan in NyQuil can cause people to have strange dreams. Some people even report a “high” or hallucinations when using this medication. These dreams may cause you to wake up and then not be able to fall back to sleep.

Long term that is not going to be a good thing for your sleep patterns because it can disrupt the rapid eye movement (REM) sleep cycles. REM sleep is the most important to your body and healing.


The antihistamine doxylamine will cause you to feel drowsy. However, there are many unwanted side effects that come from antihistamines. These effects can be much worse in older adults. So much so it makes use in these patients very questionable. Side effects include:

  • Dry mouth
  • Dry eyes
  • Blurred vision
  • Urinary retention
  • Mucous thickening
  • Dizziness
  • Low blood pressure
  • Increased heart rate
  • Constipation

9. Does NyQuil Make You Drowsy The Next Day?

Pharmacists like to answer this question based on something known as a drugs half life. This simply means how long does it take for the amount of drug in the body to be down to 50% of what it originally was.

For NyQuil the half life is about 10 hours.

Most people will take NyQuil before bedtime and wakeup after sleeping for about 8 hours. That means there is still more than 50% of the dose in your system when you wake up. Therefore, you should plan on still having some affects the next morning when you wake up.

If you took more than one dose of NyQuil the previous day, then expect even more drowsiness the following day.

This is why there is often thought to be a hangover effect from taking NyQuil, that will indeed make you drowsy the next day.


Awakening with grogginess and impaired muscle coordination due to NyQuil still being in your system can be dangerous. Especially in older people who are more at risk for medication side effects. Many people end up falling and hurting themselves due to antihistamine use.

10. Is NyQuil Addictive?

You should not use NyQuil for longer than 7 days without consulting your doctor or pharmacist. In most cases using NyQuil short term for cold and flu symptoms will not lead to addiction. However, with extended use people may notice that they need higher or more frequent doses to experience the same effects.

In these instances the body is developing a tolerance as the liver becomes faster at metabolizing the ingredients. Another concern for addiction is that two of the ingredients cross the blood brain barrier and directly work in the central nervous system.

  • Dextromethorphan
  • Doxylamine

This makes the probability of addiction and withdrawal more likely. If questions like these start to arise, you should contact your doctor about next steps:

  • Is it okay to take NyQuil every night to sleep?
  • Can I take NyQuil instead of my sleeping pills?
  • Should I take NyQuil with my other sleeping pills?

Unfortunately, many teens and young adults may abuse dextromethorphan. Taking large doses can give them the feeling of a buzz or high. This practice is dangerous and should be avoided. When taking large doses of NyQuil to get the effect from dextromethorphan they are likely to be impaired by the large dose of anthistamine as well. This is especially concerning if operating motor vehicles after use.

 11. Does NyQuil Cause Anxiety?

At normal doses NyQuil should not cause anxiety. When taken as a short term treatment for cold and flu symptoms it may actually calm anxiety. In fact, there are many cases where antihistamines are used to treat anxiety.

The only time anxiety could be an issue is when there is long term use and the body has developed a tolerance. In these cases, withdrawal could lead to anxiety.

Click here to get Dr. Jason Reed’s exclusive list of medication questions you MUST ask your doctor, for FREE!

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Supiyaphun, Pakpoom. et.al. Treatment of the common cold. J Med Assoc Thai. 2003 Jun. Supplements 2: s362-72.

Croghban, Mary S. et.al. Clinical Trial Examining Effectiveness of Three Cough Syrups. J Am Board Fam Practice. 1993 Mar. 109-114.