When you get sick, the last thing you want to do is crawl back under your covers and cuddle up with a book. Instead, most of us just want to feel better as quickly as possible. With that in mind, it’s no wonder that we often turn to over-the-counter medications like Nyquil when we’re feeling under the weather.

However, if you’ve ever taken Nyquil before, you might have noticed some concerning side effects. As soon as you take it, your body begins to react in very specific ways. And since icky things like excess sweating or nausea are common side effects of Nyquil, many people wonder how long does Nyquil last in your system?

How Long Does Nyquil Last In Your System?

The short answer to how long does Nyquil last in your system is that it varies depending on which kind of test you’re being tested for. Nyquil contains Dextromethorphan, or DM for short. This is the active ingredient that is used to treat a variety of symptoms like cough, congestion, and fever.

When you take a dose of Nyquil, this medication is metabolized by your liver and converted into a variety of metabolites. These metabolites then leave your system via your urine, feces, sweat, and breath. So the amount of time that each one of these substances is detectable in your system is how long does Nyquil last in your system.

What Happens When You Take Nyquil?

Your metabolism is slowed: This means that your body will not metabolize food as efficiently, which can cause you to gain weight. In addition, it can lead to dehydration, which is not only uncomfortable but can also be dangerous in extreme cases.

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You experience a mild state of euphoria: This is because DM is a mild hallucinogenic drug. It interferes with the breakdown of neurotransmitters like serotonin, dopamine, and norepinephrine, which causes a state of mild euphoria.

You sweat profusely: The same metabolic pathway that causes you to retain water also causes you to secrete a ton of sweat. This is why you are likely to experience profuse sweating when taking Nyquil.

You have increased salivation: This is another symptom of metabolic pathway interference. Saliva production is controlled by the same hormones that control tear production, so when your system is flooded with those hormones, you will experience a sudden increase in saliva production.

You have trouble sleeping: This is because DM is a mild wakefulness agent. The metabolic pathway that turns it into a metabolite that is excreted in your urine is also the pathway that is responsible for your REM sleep cycles.

You experience a mild hallucination: This is dependent on how much DM you take. If you take too much, you may experience hallucinations even while awake.

How Long Does Nyquil Last in Your Urine?

The metabolic pathway that converts DM into the metabolites that are excreted in your urine is responsible for a lot of its side effects. Since this pathway is the primary mechanism by which the drug is eliminated, it is also the primary mechanism by which to test for the drug in your system. DM is a very common drug that is widely tested for in the workplace, particularly in industries where workers are required to be awake for long shifts.

However, since it is also a common OTC drug, it is often included in urine drug tests for students. Unlike blood tests, urine tests can be done at home and require no special equipment. This means that the standard detection period for DM can vary wildly depending on which test you’re taking.

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How Long Does Nyquil Stay in Your Blood?

Blood tests are used to test for the presence of a particular virus or bacteria in the bloodstream. Since Nyquil is not a cure for any kind of disease, it is unlikely to be found in your blood unless you have a bacterial infection like pneumonia. If you test positive for DM in your blood, it is unlikely to be due to taking Nyquil. It is more likely that you are suffering from an infection.

Since these infections are bacterial and will not disappear without treatment, they can be detected in the bloodstream for weeks. This means that if you test positive for DM in your bloodstream and you know that you have not been taking any OTC medications, you need to see a doctor. This is a sign that you have a bacterial infection in your lungs or other parts of your respiratory tract and will require antibiotics to treat.

How Long Does Nyquil Last in Your Breath?

Like the other tests, the metabolic pathway that converts DM into a metabolite that is detected in your breath is the same one that is responsible for its side effects. This means that your breath will smell strongly of fruity cough syrup, which can be embarrassing if you don’t know that it is a normal side effect of taking Nyquil.

However, it also means that the detection period for DM in your breath is the same as in your urine. Since DM is excreted in your breath in the same way that it is excreted in your urine, it can be detected in your breath for weeks after you take it. If you have recently taken Nyquil and you fail a breathalyzer test, you can argue that the drug is still in your system and that it caused you to have a false positive.

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However, if you have been taking Nyquil for a long period of time, it is unlikely that a breathalyzer test will detect any DM left in your system.

How Long Does Nyquil Last in Your Blood?


Blood tests can be used to test for the presence of certain antibodies in your blood. This is common among people who are undergoing treatment for HIV and other diseases. Since Nyquil does not cure any diseases and does not create antibodies, it is unlikely to be found in your blood. However, it is possible that a blood test may detect the presence of DM in your blood.

This is because some blood tests check for the metabolites of DM in your blood rather than the drug itself. This means that if you are taking Nyquil, it could show up in your blood test for weeks.

Final Words

When you get sick, the last thing you want to do is crawl back under your covers and cuddle up with a book. Instead, most of us just want to feel better as quickly as possible. With that in mind, it’s no wonder that we often turn to over-the-counter medications like Nyquil when we’re feeling under the weather. However, if you’ve ever taken Nyquil before, you might have noticed some concerning side effects.

As soon as you take it, your body begins to react in very specific ways. And since icky things like excess sweating or nausea are common side effects of Nyquil, many people wonder how long does Nyquil last in your system?


David Warren
Author

David Warren is a pharmaceutical specialist that dispenses prescription medication on a daily basis. He received a Bachelor of Science degree in pharmacy from the University of Tennessee in 1991. With over 50 publications on medication-related and pharmacy topics, David has been able to share his experiences and knowledge with others. David with lots of experience and knowledge in medications that are utilized to treat a wide range of medical conditions. Before David dispenses a medication to a patient, he will go over the side effects, dosage recommendation and contraindications.

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