How Long After Dayquil Can I Take Nyquil (And Why)?

How Long After Dayquil Can I Take Nyquil (And Why)?

Exact Answer: 4 to 6 hours

Dayquil is a drug that is used to battle the symptoms of cold and flu in an individual. It is a mixture of acetaminophen, dextromethorphan, and phenylephrine. The drug helps assuage symptoms like fever, cough, cold, nasal congestion, headaches, etc. It is used mostly during the day to relieve the patient of these flu symptoms.

Nyquil, on the other hand, is a very similar drug with just one difference. It works in the same way as Dayquil but is prescribed for consumption during the night. The drug has a drowsy effect on patients and thus, is not suitable for ingestion during the day.  

How Long After Dayquil Can I Take Nyquil

How Long After Dayquil Can I Take Nyquil?

According to most physicians, the drug Dayquil is better suited for consumption during the daytime, while Nyquil is prescribed for ingestion at night. However, patients suffering from severe cold symptoms, who want relief both during the day and night, can consume both drugs on the dame day.

There is a catch to this assertion. The patient must wait for at least 4 to 6 hours before he or she ingests a dose of Nyquil after already having taken a dose of Dayquil in the morning. This time interval between the two drugs is considered important for the patient to experience immediate relief upon ingesting the second drug dose.

Some patients take the Nyquil dose merely 4 hours after the Dayquil dose is ingested. Although this lower limit is considered to be within the safety window, it is always advisable to choose a median time frame- i.e. 5 hours in this case- to re-dose yourself. The chemical composition of both the drugs is so similar that it can affect the patient’s body if the first dose is not completely digested or partially eliminated.

However, most medical professional have pointed out that if the patient in question does not have any several existing co-morbidity or chronic condition, he or she can easily take the two drugs on the same day with a diligently maintained interval of up to 6 hours. Although this is a stated fact, it is always better to consult a doctor about your specific health issues and symptoms before opting for the self-medication route.


In Summary:

Dosage Time LimitWaiting Period
Lower Limit4 hours
Upper Limit6 hours

Why Do You Have To Wait So Long After Dayquil To Take Nyquil?

Doctors suggest that a patient wait for his or her body to partially process the Dayquil drug’s contents before opting for a dosage of Nyquil. There is a scientific reason behind this proposition. Taking the Nyquil dose much too soon can severely harm the patient’s body.

Both the drugs contain acetaminophen, which is a common fever reducer used in many flu medicines. However, one of the chemical components it is broken down to is extremely toxic for the liver. The body has a process of eliminating these toxins, however, it takes time to do so.  

Thus, to prevent an overload of this chemical in the body of the patient, doctors encourage a gap between the ingestion of Dayquil and Nyquil. Individually as well, patients are deterred from consuming more than 4 doses of each drug within a 24-hour window of time.  This is also based on the acetaminophen content of the drugs.


Moreover, until a part of Dayquil has withered off after being successfully processed by the body, the Nyquil dosage will not show much difference. The patient will feel visible relief only when he or she allows the previous dose to work and then takes Nyquil.

Lastly, since Dayquil is taken during the day, its effects may start wearing off by nightfall. This means after 6 hours or more the symptoms and discomfort might return. Then the patient can take a dose of Nyquil as it will also help the individual sleep easily. Nyquil contains Doxylamine as one of the active ingredients in the chemical concoction of the drug. It is known to make patients drowsy and is best suited for the nighttime.


Both Dayquil and Nyquil are used to assuage the symptoms of common cold and flu. However, they are variegated in terms of their correct times of taking the prescribed dosage. The active ingredients in Nyquil make it unsuitable for consumption in the morning or during the daytime. Thus, Dayquil needs to be taken in the morning to help relieve the cold symptoms.

However, one can take both drugs together on the same day. This does not imply that both have to be taken one after another. A time period of 4 to 6 hours between Dayquil and Nyquil is considered ideal by most medical professionals.  


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Hi! I'm Nidhi.

Here at the EHL, it's all about delicious, easy recipes for casual entertaining. So come and join me at the beach, relax and enjoy the food.


  1. The explanation of the chemical composition and potential harm to the body if the doses are taken too close together is well articulated in this post. Thanks for sharing.

    1. Absolutely, the reminder to consult a doctor before self-medicating is also important to highlight. We should prioritize our health and safety.

  2. The explanation of why the waiting period is important is well-supported by scientific reasoning in this article. I’ll be sure to share this with friends and family.

    1. Agreed. The importance of understanding the safety limits and chemical composition cannot be overstated. Knowledge is power.

  3. Thank you for addressing the potential risks of consuming both medications too closely together. Safety should always come first.

    1. Absolutely, Steve. This post serves as a valuable resource for anyone seeking guidance on the usage of DayQuil and NyQuil.

  4. The comprehensive explanation of the chemical impact on the body and the importance of allowing the previous dose to work before taking NyQuil is spot on. Kudos for this insightful post.

    1. Well said, Xharrison. This post has effectively conveyed the significance of maintaining a safe interval between doses for optimal health outcomes.

  5. Very informative post! I appreciate the detailed explanation of why it’s important to wait 4-6 hours before taking NyQuil after DayQuil.

    1. Yes, this post is a must-read for anyone considering taking both medications in the same day. It’s crucial to understand the time frame between doses.

    2. I completely agree! This post really shed some light on the potential dangers of not waiting long enough between doses.

  6. This post makes a compelling argument for why waiting 4-6 hours is necessary. I appreciate the emphasis on seeking professional medical advice before making a decision.

    1. Definitely. It’s crucial to prioritize the body’s processing of the medications to avoid adverse effects. Well done.

    2. I couldn’t agree more. The information is presented in a clear and understandable way, which is beneficial for readers.

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