Will NyQuil Show Up In A Drug Test? (Medications Causing False Positives)

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Taking NyQuil in the recommended dosage is beneficial in curing your cold. Taking NyQuil in larger quantities (substance abuse) or taking it for an extended period can result in a positive drug test. The main reasons being that NyQuil consists of substances such as antihistamines and methamphetamine, highly addictive drugs, if not taken in recommended dosage. As long as you take the recommended dosage can keep you from testing positive for drugs.

When it comes to taking medicine for your cold, the over-the-counter medications come in pretty handy in providing some relief. Nyquil is one such medicine.

Usually taken at night by people since it makes one drowsy. It’s a very common medication to help recover a person from a cold.

But does taking NyQuil have some side effects, like showing up positive in a drug test? Let’s find out possible causes and understand how taking NyQuil can also show a false positive. Also, the precautions to keep in mind and avoid testing positive depending on the dosage.

Nyquil and false positive

Taking NyQuil can be good for relieving your cold and make you feel better as you rest for the night but have you ever wondered how that happens. Nyquil contains substances such as antihistamines and hypnotics.

All the over-the-counter medications for cold contains this substance as this is a sedative drug put in all these medicines to provide the consumer with relief. As per studies, antihistamines can affect drug tests to a great extent and show a person a false positive.


Methamphetamine is a potent, highly addictive stimulant that affects the central nervous system. But why should you be worried about this drug?

Those who take NyQuil to treat their cold are also at risk of being accused of taking methamphetamines. You can even get a positive drug test for methamphetamine present in your blood.

It can even cause innocent individuals to test positive for this particular drug. Then they could be charged for any drug-based crime solely on the blood testing, all for taking cold medicine.

Other drugs bringing positive

Antihistamines can affect drug tests. In NyQuil, the dominant antihistamine present is doxylamine succinate.

  • Doxylamine succinate can appear in urine drug tests such as methadone, other opiates, and amphetamine-like PCP.
  • Nyquil also contains a drug suppressant called Dextromethorphan, which can also appear in the urine drug tests such as a PCP.
  • Both Doxylamine Succinate and Dextromethorphan have a half-life of approximately 10-12 hours. As a result, false positive drug tests scores usually occur within 12 hours of taking NyQuil.
  • Using NyQuil could also produce a false positive for Ecstasy or MDMA.

Nyquil and recommended dosage

But if this were to be true that taking NyQuil is actually putting a lot of people in danger for testing positive for a drug test, how is it still sold so wildly? Should you stop taking NyQuil?

The answer is no, not at all. Visiting your doctor when you’re sick is recommended for a reason. When they prescribe medicines, they also provide you with recommended dosage for every medication.

Take NyQuil based on your doctor’s prescription or the dosage recommended on the bottle. You won’t have to worry about testing positive for any drug test. Keeping in mind, you only take NyQuil for the recommended days.

If you end up taking bottles of NyQuil without any dosage preference or take it for more extended periods, they’re going to create a problem.

Taking more than the preferred dosage can increase the amount of the drugs such as methamphetamine. Taking it for a more extended period can also accumulate this drug in your body, thus testing positive.

Avoiding positive drug test

  • Your first precaution should always be to take NyQuil in the recommended dosage as prescribed by your doctor or written on the bottle. Taking small quantities for your cold won’t get you into trouble or get you tested positive.
  • If you have a clue or know that you can be drug tested in a few days, then you can easily prevent being tested positive if you stop using NyQuil for a few days.
  • There’s research that shows ways to eliminate metabolites faster using THC cleaner kits. You should use research-supported supplements and not anything that sells on Amazon.
  • If you’re facing drug crime charges due to taking NyQuil, then calling an experienced drug crime defense lawyer is the best way to minimize the consequences.

Nyquil causing positive alcohol test

If you drank several bottles of NyQuil, only then will you get high alcohol reading over a .02.

Since NyQuil contains a high amount of alcohol, you should not use it when alcohol testing. It can also come out as a high alcohol reading if you have just taken the recommended dosage of NyQuil and immediately test for it.

Though interlock devices are not always accurate, you should still avoid NyQuil as a substance for alcohol testing. Let’s understand this in more depth.

A person’s blood alcohol content reduces about 0.02 an hour once a person has stopped drinking. Nyquil contains 10% to even up to 25% of alcohol.

Drinking one bottle will barely bring it to 0.02, but drinking several bottles might.

So, many people even use NyQuil as an excuse to get out of being held for drinking and driving. But the court and officers have heard the cough syrup and NyQuil defense too many times. So, even if you’re telling the truth, they will believe you’re lying to cover up the fact that you were driving under the influence.

Other medications causing false positives

Like NyQuil, other medications can lead to false positives in people. So being aware of them and taking the necessary precautions mentioned above can get you to not test positive.

  • Ibuprofen is the active ingredient in Advil, which could lead to false positives for marijuana.
  • Benadryl could lead to false positive for Benzodiazepines or PCP
  • Claritin taken for seasonal allergies contains the active ingredient Loratadine, leading to false positives for drugs such as methamphetamine or Ecstasy.
  • Mucinex DM contains active ingredients that could lead to false positives for heroin, opiates, and morphine.
  • Nasal spray such as Afrin could also lead to a false positive for meth and Ecstasy.


What should I avoid before a drug test?

Before 24 hours of the drug test, you should avoid strenuous exercise and the substances and drugs such as Acetaminophen, alcohol, antihistamines, Aspirin, caffeine, vitamin B.

Does Tylenol cold and flu show up on a drug test?

Codeine is used in Tylenol and other medications to counter cough or the aches and pains of the flu. It is an opiate. When codeine enters the body and is metabolized, it changes to morphine. Therefore, you may end up with a positive drug screen for codeine and or morphine.

How long it takes for NyQuil to wear off?

Depending on one person to person and the dosage taken will change the time taken for NyQuil to wear off. In terms of sleeping, while for some, 5-6 hours of sleep is all they need, they might need 7-8 hours for others.

How long does cold medicine stay in your system?

If taken according to the prescribed dosage, any cold medicine might take 9-29 hours to fully get rid of the dextrorphanol after a person’s last dosage.

Can you get high off of NyQuil?

If taken more than the recommended dosage, Nyquil can also become highly addictive to the point where a person can get high off of it. The ingredient in NyQuil, Dextromethorphan, can give people a high and induce buzz-like euphoric feelings.

To summarize

Nyquil comes to the rescue of millions of people when they suffer from cold and is an excellent over-the-counter medication to get some much-needed relief. But even medications like NyQuil can be problematic, leading to a false positive when tested for drugs.

This problem occurs if you go over the prescribed dosage of this medication, such as taking several bottles within a short span of hours or taking it for an extended period. When you do this, antihistamine and methamphetamine present in NyQuil can act as the basis for testing positive. Therefore, both drugs should be taken in a recommended dosage.

Like NyQuil, there are other medications too. If taken more than the prescribed dosage might lead to a false positive. As long as you follow your doctor’s prescription or the recommended dosage on the bottle, you will feel completely okay and won’t face the risk of testing positive.

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Saumya Malik
I'm an ardent follower of everything good for the health and wellness of body and mind. I am passionate about providing effective solutions to general health and mental well-being issues and wants to help people achieve the same. When I'm not writing, you can find me curled up with a good book in a corner or cooking as a form of good mental therapy.

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