Does Nyquil Go Bad

In this brief article we will be answering the question, “does Nyquil go bad?”. We will also tell you the benefits, uses, and side effects of Nyquil, and will highlight important details about expired medicines and how to properly store them.

Does Nyquil Go Bad?

Not really. It is quite uncommon that expired medicine will ‘go bad’ and result in health issues on consumption. There are no reports that expired Nyquil degrades into harmful components.

However, using ANY medicine past its expiration date is not recommended, since medicines past their expiry date lose their potency and effectiveness. 

Also, since Nyquil is considerably inexpensive and easily available, it’s best to replace an expired bottle with a new one. 

What is Nyquil?

Nyquil is a combination of three drugs: acetaminophen, dextromethorphan, and doxylamine (2).

  • Acetaminophen is a pain reliever and fever reducer.
  • Dextromethorphan is a cough suppressant. It affects the cough reflex in the brain that triggers coughing.
  • Doxylamine is an antihistamine that reduces the effects of the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. 

Nyquil is an OTC (over-the-counter) medication used to treat symptoms of flu and the common cold that usually aggravate during nighttime. It is available in liquid form as well as gel capsules.

Nyquil is effective against the following symptoms:

  • sneezing
  • runny nose
  • sore throat and cough
  • fever
  • headache
  • minor aches and pains

A stronger version of Nyquil, Nyquil SEVERE, provides maximum symptomatic relief for the symptoms of cold at night. Nyquil Cough Suppressant specifically relieves cough.

How Often Can You Take Nyquil?

The recommended dosage for adults and children (12 years and older) is two LiquiCaps with water every six hours, or 30 ml of Nyquil Liquid every six hours.

Do not take more than four doses of Nyquil in a day.

Use exactly as directed on the label, or as prescribed by your doctor. Do not use for longer than recommended. Cough and cold medicine is usually taken only for a short time until your symptoms clear up.

Do not take more of this medication than is recommended. An overdose of acetaminophen can damage your liver or cause death (2).

How Long Does Nyquil Take To Work?

Nyquil usually begins to provide relief within 30 minutes of taking the medicine. However, this depends on various factors such as age, weight, the severity of symptoms, overall health, metabolism, and liver function.

What Are The Side Effects of Nyquil?

Nyquil can cause drowsiness and dizziness, so it is important to avoid using heavy machinery or driving a vehicle when taking Nyquil.

Also, avoid consuming alcoholic drinks when taking Nyquil since this can interfere with the metabolism and effectiveness of the medication.

In children, Nyquil can cause excitability.

The first signs of an overdose include loss of appetite, nausea, vomiting, stomach pain, sweating, and confusion or weakness. Later symptoms may include pain in your upper stomach, dark urine, and yellowing of your skin or the whites of your eyes. Signs of an allergic reaction are hives; difficult breathing; swelling of your face, lips, tongue, or throat. (2).

What Concerns Are Associated With Medicines That Go Bad?

Besides the fact that medicines may internally degrade and become less effective over time, it is important to note that certain expired medicines do exhibit noticeable changes as well.

For instance, an expired bottle of aspirin usually starts to smell like vinegar. This is because the salicylic acid in aspirin begins to break down and produce acetic acid, or vinegar. However, it is extremely rare for expired medicines such as Nyquil to degrade into their components and harm you.

The greater concern associated with medicine that might have gone bad is spoilage and contamination. This generally happens when medicines are not stored under proper conditions.

Liquid medications are usually mixed with preservatives; thus, when the expiration date is breached, the preservatives can no longer work properly, and the chemical compositions of the drugs begin to break down. Occasionally dangerous by-products are formed that can be hazardous to body organs that can get impaired and body loses the ability to filter toxins and various chemical metabolites from the system, leading to serious health hazards. These by-products can even be carcinogenic, which if extrapolated as additional clinical failure, can lead to mortality; therefore, strict compliance with expiry dates ought not to be ignored. Although no significant deaths were recorded in any study due to use of expired drugs, most of the national and international articles directly or indirectly reveal their adverse effects (3). 

How Can You Prevent Medicines From Going Bad?

Storage in high heat and/or humidity can accelerate the degradation of some drug formulations (1). Here are a few tips to store medicines properly and extend their shelf life:

  • Always store medicine in a cool, dark place such as a pantry. Unless recommended by the manufacturer, do not refrigerate medicines. 
  • Keep medicines away from direct sunlight and avoid exposure to direct heat. Also, do not store medicines near sources of heat, such as the stove.
  • Keep medicines tightly sealed to prevent exposure to moisture which could result in the growth of bacteria and mold. This applies to both new and in-use medicines.
  • Certain medications, especially liquid-based, come with the risk of bacterial contamination since their preservatives only remain effective for a finite period. These medicines should not be used if they’ve been opened and stored for a long time.

What Happens If You Take Expired Medication?

Adverse effects of expired drugs are loss of efficacy, safety, potency and formation of harmful products (3). Taking expired medication could have dangerous consequences, but these are usually associated with medicines meant to treat infections and major conditions such as blood pressure or diabetes. 

As mentioned, an expired medicine might not have spoiled, but it certainly loses its potency over time. In Nyquil’s case, a bottle with reduced potency simply wouldn’t provide effective and timely relief for cough and flu as compared to one that is in-date. 

However, if medication treating serious conditions lose their potency and don’t remain effective, it could cause serious health complications, such as a chronic infection that won’t clear up, or uncontrolled blood pressure and blood glucose. 

Also, for most expired medicines including Nyquil, it is almost impossible to determine whether they have lost potency with time without proper testing and analysis. 

So, since most medicines show no outward signs of degradation or loss of potency, it is best to replace expired medication with a new one.

How Are Expiration Dates Determined?

To determine expiration dates, manufacturers conduct various stability tests. However, these tests are performed up to a certain time period, generally, two to three years, after which there is no data to determine whether the medicine will remain stable or not. 

This is mainly due to financial constraints and because most medicines are generally consumed within a few years, so additional testing is a waste of time and resources. 

So basically, a medicine’s expiration date is designated based on how long the manufacturer has data for. 

The manufacturer’s expiration date is based on the stability of the drug in the original sealed container. The date does not necessarily mean that the drug was found to be unstable after a longer period; it only means that real-time data or extrapolations from accelerated degradation studies indicate that the drug in the closed container will still be stable at that date. Most drug products have a labeled shelf life of 1-5 years, but once the original container is opened, the expiration date on that container no longer applies. However, there are no published reports of human toxicity due to ingestion, injection, or topical application of a current drug formulation after its expiration date (1).  


In this brief article we will be answering the question, “does Nyquil go bad?”. We also told you the benefits, uses, and side effects of Nyquil, and highlighted important details about expired medicines and how to properly store them.

If you have any more questions or comments please let us know.


  1. Heat, Humidity. Drugs Past Their Expiration Date., JAMA, 2016, 315, 510-511.
  2. Acetaminophen, dextromethorphan, and doxylamine. University of Michigan Health. 2015.
  3. Gul, Aleesha, et al. Expired drugs-awareness and practices of outdoor patients. J Rawalpindi Med Coll Stud Sup, 2016, 20, 45-48.

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