How Long Does DayQuil Last? [How Long It Stays in Your System]

DayQuil is an over-the-counter medication that treats multi-symptom cold medicine, including nasal congestion, cough, fever, headache, and minor aches and pains. How long does the effect of DayQuil last, and how long does it stay in your system?

DayQuil lasts for approximately 4 hours. The recommended dose is 30 mL (2 TBSP) every 4 hours. DayQuil Cough provides cough relief for up to 8 hours. DayQuil stays in your system for 24 to 36 hours before it is eliminated from your body.

Read on to find out more about how long DayQuil lasts, proper dosage, storage, and more.

How Long Does DayQuil Last?

how long does dayquil last

DayQuil has become a popular choice as an over-the-counter drug because it relieves many symptoms associated with the common cold and influenza without compromising alertness and cognitive function.

DayQuil lasts for approximately four hours. DayQuil contains a cough medication called Dextromethorphan, which lasts approximately 4 hours, up to a maximum of 6 hours. You can expect this drug to stay in your system for around 24-36 hours.

DayQuil is absorbed quickly from your stomach and works in as fast as 30 minutes. DayQuil can be taken every four hours. You can take DayQuil Cough every 6 to 8 hours. Some DayQuil products contain more Dextromethorphan, a cough medication that lasts 6 to 8 hours in your system. Always read the product label on your DayQuil product to know the exact dosage.

You may still experience some side effects of DayQuil even after you have stopped taking medicine and are over your sickness. This is because DayQuil is still in your system. Elimination of this drug from your system depends on the DayQuil product you took. However, the time it takes to be eliminated from your system will depend on what DayQuil product you took.

Available DayQuil Formulations

  • DayQuil Cold and Flu – contains Acetaminophen, Dextromethorphan, and Phenylephrine
  • DayQuil Cough – contains Dextromethorphan
  • DayQuil Severe Cold and Flu – contains Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine.
  • DayQuil Mucus Control – contains Guaifenesin and Dextromethorphan.

Next, we’ll take a look at how much time it would take for each ingredient to be eliminated from your system. To eliminate acetaminophen in your system will take about 22 hours. Of all the active ingredients found in NyQuil, Guaifenesin has the shortest elimination time, 6 hours. Phenylephrine takes about 17 hours to eliminate from your system.

Dextromethorphan is the ingredient that takes the longest to eliminate from your body at 33 hours from ingestion. So, it is safe to conclude that DayQuil elimination from your system will happen within 24 to 36 hours.

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How Does DayQuil Work?

DayQuil is a multi-symptom cold and flu product by Proctor and Gamble, under the brand Vicks. It is available as an over-the-counter drug. It treats the flu and the common cold symptoms, including fever, cough, nasal congestion, fever, and minor aches and pains.

Taking DayQuil during the day will not make you drowsy. DayQuil lasts for about 4 to 6 hours. It stays in your system for 24 to 36 hours. See our article on taking DayQuil at night to learn more about the effects of Dayquil.


NyQuil, a product from the same makers, was formulated to be taken at night as it has an added active ingredient, doxylamine. Doxylamine is an antihistamine that relieves your allergy symptoms. However, this ingredient can make you drowsy. To learn more about NyQuil, see our article on taking NyQuil during the day.

Acetaminophen works to reduce fever and is also a pain reliever. It changes the regulation of your body’s temperature and how your body reacts to pain. On the other hand, Phenylephrine is a nasal decongestant that lessens the swelling of blood vessels in your sinuses, allowing you to breathe easily.

Dextromethorphan is a cough suppressant that sends signals to your brain that lessens your urge to cough. Guaifenesin thins mucus so that you can cough it up easier.

DayQuil Dosage

LiquiCaps refer to DayQuil capsule preparations that contain liquid inside. It also comes in liquid form, both for adults and for children. Moreover, it is best to consult your doctor if your child is below 6 years old.

Let’s look at the recommended dosage according to age group. Also, you should not give DayQuil to children below 4 years old.

Adults and Children 12 Years and Above

  • For LiquiCaps – two capsules every 4 hours. Do not exceed more than 4 doses in 24 hours.
  • For liquid – 30ml every 4 hours. Do not exceed 4 doses in 24 hours.

Children 6 – 11 Years Old

  • For LiquiCaps – not recommended
  • For liquid – 15ml every 4 hours. Do not exceed 4 doses in 24 hours.

Consult your doctor if symptoms do not improve after taking DayQuil for two days.

What If You Miss a Dayquil Dose?

DayQuil is actually a medication you can use as needed, and it’s ok for you not to be on scheduled doses. However, if your doctor has put you on a dosing schedule and you miss a dose, take it as soon as you remember.

If it is almost time for your next dose, skip the missed dose and take the medication on your next scheduled dose. Lastly, do not add more medicine to your next dose to make up for the missed one.

Can You Take DayQuil at Night? Will It Keep You Up?

DayQuil Side Effects

how long does dayquil stay in your system

As with most medications, DayQuil can cause some side effects. Many of these side effects do not warrant medical attention, but you still need to be aware of them. The side effects will usually go away because your body will adjust to the medicine.

Common Side Effects

  • Lightheadedness
  • Drowsiness
  • Dizziness
  • Stomach Pain
  • Nausea
  • Vomiting
  • Nervousness
  • Difficulty sleeping

If you’re taking DayQuil, avoid eating grapefruit or drinking grapefruit juice. It has been studied that eating grapefruit and taking dextromethorphan (an active ingredient in DayQuil) can increase the levels of dextromethorphan in your system. Thus, boosting the side effects of DayQuil, like dizziness and nervousness.

Other Side Effects

The following are less common side effects but are more severe:

  • Rash
  • Itching
  • Hives
  • Red skin that is peeling or blistering
  • Breathing difficulties
  • Difficulty in swallowing
  • Face swelling including lips, tongue, and throat
  • Swelling of hands and feet

Although these side effects are not common, if you experience any of them while taking DayQuil, get emergency medical attention immediately.

Again, how long does DayQuil last? We mentioned that DayQuil lasts for approximately four hours. And if the formulation of DayQuil you are taking contains a cough medication called Dextromethorphan, the cough medication lasts approximately 6 hours. DayQuil stays in your system for 24 to 36 hours before it is eliminated from your body.

If you still experience any side effects 24 to 36 hours after taking your last dose of DayQuil, consult a doctor, as the medicine is out of your system by this time.

How to Properly Take DayQuil

1. Always Use as Directed

DayQuil comes with dosing instructions on their product label. Follow exactly what is on the label or as prescribed by your doctor. Do not take in smaller or larger doses than what has been recommended. Stop taking DayQuil when your symptoms have cleared up.

Do not take for more than 7 days. Consult your doctor if you still have a fever after 3 days, still have pain after 7 days, if you develop a rash, or if your symptoms get worse.

2. Use the Measuring Spoon or Cup That Comes with It

DayQuil liquid will come with either a measuring spoon or a medicine cup. Use this to measure your liquid DayQuil, and do not use an ordinary spoon. Lastly, if you lose your medicine cup, ask your pharmacist for one.

3. Inform Your Doctor If You’re Having Surgery or Other Medical Procedures

Let your doctor know that you’re taking DayQuil or have taken it in the last 2 days. DayQuil may interact with other medications you’ll need to take post-surgery.

4. Store Properly

Store DayQuil properly. Keep away from moisture and heat. Also, do not store it in the freezer.

DayQuil FAQs

how does dayquil work

What Are the Drugs You Should Avoid while Taking DayQuil?

You need to avoid some medications while taking DayQuil because the active ingredients (like Acetaminophen) in DayQuil can interact with them. These interactions may change how the drug works as well as its effectiveness. They could also increase your chances of experiencing more severe side effects.

Acetaminophen Interact with These Drugs:

  • Carbamazepine
  • Isoniazid
  • Phenobarbital
  • Phenytoin
  • Phenothiazine
  • Warfarin

DayQuil also contains phenylephrine and dextromethorphan, which interact with monoamine oxidase inhibitors or MAOIs. MAOIs stay in your system for approximately two weeks, and so, if you’ve taken them in the last two weeks, there could still be drug interactions.


  • Isocarboxazid
  • Phenelzine
  • Selegiline
  • Tranylcypromine

Is DayQuil Safe?

DayQuil is a safe drug to use for most people. However, you should avoid it if you have the following medical conditions because they might harm you. Ask your doctor if you can take DayQuil if you have any of the following medical conditions:

  • Blockage in your stomach or intestines
  • Heart disease
  • High blood pressure
  • Diabetes
  • Liver Disease
  • Thyroid Disease
  • Enlarged prostate that makes urinating difficult

Is DayQuil Misuse Possible?

Like all drugs, misuse of DayQuil is possible. It isn’t for all types of cough. Avoid using DayQuil to treat a productive cough or a cough where you can cough up your mucus. Also, avoid using dayQuil for the following conditions:

  • Cough associated with asthma,
  • Smoker’s cough,
  • Chronic bronchitis, or emphysema.

Your doctor knows how to treat said conditions by prescribing a different drug.

DayQuil contains dextromethorphan, an often misused drug. Note that too much dextromethorphan can cause hallucinations, and in very high doses, it can cause death. Also, remember to take DayQuil only in safe dosages. You can check the product label for the proper dosing.

What Will Happen If You Take Too Much DayQuil?

If you take too much DayQuil too often, it can cause damage to your liver from the acetaminophen. You need to make sure that you are not taking acetaminophen or any other medication that contains acetaminophen while you are taking DayQuil.

This can cause an overdose of acetaminophen. Also, remember not to exceed 4 doses of DayQuil in a period of 24 hours and not to take it for more than 7 days.

If you accidentally take too much DayQuil, call your local poison control center. If you know anyone who has taken too much DayQuil, call 911 and seek medical attention for the person immediately.

How to Properly Store DayQuil?

Store DayQuil away from light and moisture. As with all medicine, keep DayQuil away from children and pets. Read and follow the product label for storage instructions.

When DayQuil expires, consult your pharmacist or local waste disposal company about how to discard your product safely. Do not flush any medication down the toilet or pour them down the drain.

Conclusion: How Long Does DayQuil Last? How Long Does DayQuil Stay in Your System?

DayQuil’s effects last for approximately 4 to 6 hours. DayQuil Cough lasts for up to 8 hours. If the DayQuil you are taking contains a cough medication called Dextromethorphan, the maximum effect lasts approximately 6 hours.

This is why the dosage on the product labels is between 4 to 6 hours. DayQuil stays in your system for 24 to 36 hours before it is eliminated from your body.

DayQuil is an effective medication used to treat multi-symptom colds and flu. The active ingredients in DayQuil help relieve your symptoms to make you feel better.

Follow the information we gave to help you safely take DayQuil. If you’re still in doubt, consult your doctor before you use DayQuil.

Related reading:

Can You Take DayQuil at Night? Will It Keep You Up?

Can You Take NyQuil During the Day?