How Long Does Dayquil Last? & Remain in Your System

logo by Editorial Staff | Updated on December 17th, 2022

DayQuil is an over-the-counter cold treatment relieves symptoms such as nasal congestion, cough, fever, headache, and mild aches and pains. How long does DayQuil’s impact persist, and how long does it stay in your system?

How long does DayQuil remain active in your system?

DayQuil is primarily composed of four ingredients: acetaminophen, dextromethorphan, guaifenesin, and phenylephrine. Guaifenesin has the lowest half-life in plasma, lasting around an hour, whereas Dextromethorphan has the longest, lasting up to 6 hours. The medicine reaches its maximal level in plasma in 1-2 hours, and the effects begin to fade after around 4 hours.


Thus, DayQuil can be used every 4 hours, but no more than 4 doses in 24 hours. DayQuil’s components are eliminated from the body after 22-24 hours.

Continue reading to learn more about how long DayQuil lasts, optimum dose, storage, and other topics.

Even after you have finished using DayQuil and recovered from your illness, you may still have some adverse effects. This is because DayQuil is still present in your system. The drug’s elimination from your system depends on your DayQuil product. However, the time it takes to be removed from your system is determined by the DayQuil product you used.

DayQuil Formulations That Are Available

  • DayQuil Cough (Dextromethorphan)
  • DayQuil Cold & Flu (Acetaminophen, Dextromethorphan, Phenylephrine)
  • DayQuil Severe Cold & Flu (Acetaminophen, Dextromethorphan, Guaifenesin, Phenylephrine)
  • DayQuil Mucus Control DM (Dextromethorphan, Guaifenesin)
  • Dayquil Sinex (Acetaminophen, Phenylephrine, or Oxymetazoline)

Following that, we’ll look at how long it would take for each element to be eradicated from your system.

Elimination Half-Life

If you want to know how long it takes the Dayquil to exit the system, you should know the time of each component, which is known technically as the Elimination Half-Life.

  • Acetaminophen: 1 to 4 hours
  • Dextromethorphan: 3 to 6 hours
  • Guaifenesin: ~1 hour
  • Oxymetazoline: 1.72 to 2.32 hours
  • Phenylephrine: 2 to 3 hours

The number may vary depending on the dose percentage. However, those above are the general elimination of half-lives of the Dayquil components.

It is obvious that Dayquil with Dextromethorphan takes the most time to eliminate itself from our system, taking roughly 3-6 hours = > 30 Hrs (approx.) to clear itself out of the plasma, whereas Acetaminophen takes 1-4 hours = 20-22 Hrs. (approx.) for complete elimination.

Guaifenesin has the quickest elimination time of 1 Hour = 6 Hours (about Post-Ingestion). Oxymetazoline has a short elimination half-life of 1.50 – 2.30 Hrs. of time = 12-13 Hrs. (avg.) for full clearance from the system. Phenylephrine has a half-life of 2-3 hours = 16 hours (approx.) before leaving the Dayquil user.

Based on the time constraints, we may conclude that most users should have removed Dayquil from their system within 22-24 to 46-48 hours (of the final dose). The function of the CYP2D6 isoenzyme will depend on the formulation, including Dextromethorphan.

Individuals who are poor metabolizers of CYP2D6 Isoenzyme will take longer to eradicate Dayquil from their system entirely.

Except for a small percentage of users categorized as Poor Isoenzyme metabolizers, the majority of Dayquil users have strong CYP2D6 metabolizers and have been observed to remove Dayquil fully out of their system roughly 2-3 days following their final dosage.

It will take around 22 hours to eradicate acetaminophen from your system. Guaifenesin has the lowest elimination duration of any active component in NyQuil, at 6 hours. It takes around 17 hours for phenylephrine to be eliminated from your system.

At 33 hours after administration, dextromethorphan is the component that takes the longest to clear from your body. As a result, it is fair to assume that DayQuil will be removed from your system within 24 to 36 hours.

How Does DayQuil Function?

Proctor & Gamble’s DayQuil is a multi-symptom cold and flu medication sold under Vicks. It is a prescription-only medication. It alleviates the flu symptoms and ordinary colds, such as fever, cough, nasal congestion, fever, and mild aches and pains.

Taking DayQuil throughout the day will not cause drowsiness. DayQuil has a duration of 4 to 6 hours. It will remain in your system for 24 to 36 hours. To understand more about the effects of Dayquil, read our page on taking it at night.

What is NyQuil

NyQuil, another medicine from the same manufacturer, was designed to be administered at night since it contains the active component doxylamine. Doxylamine is an antihistamine that helps to alleviate allergic symptoms. This substance, however, has the potential to make you sleepy. See our article on taking NyQuil throughout the day for additional information.

Acetaminophen works as a fever reducer as well as a pain reliever. It alters the management of your body’s temperature and how it responds to discomfort. Phenylephrine, on the other hand, is a nasal decongestant that reduces the enlargement of blood vessels in your sinuses, enabling you to breathe more readily.

Dextromethorphan is a cough suppressant that delivers messages to your brain, reducing your desire to cough. Guaifenesin thins mucus, making it simpler to cough.

Correct Dosage of DayQuil

LiquiCaps are DayQuil capsule formulations with liquid within. It is also available in liquid form for both adults and children. Furthermore, you should visit a doctor if your child is under six.

Let’s have a look at the dose recommendations based on age group. DayQuil should also not be given to children under the age of four.

Adults and children aged 12 and up

  • Two capsules every four hours for LiquiCaps. Do not take more than four doses in 24 hours.
  • 30ml every 4 hours for fluids. Do not take more than four doses in 24 hours.

Children 6 – 11 Years Old

LiquiCaps are not advised for children from 6 to 11 years old.

15ml every 4 hours for fluids. Do not take more than four doses in 24 hours.

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

What If You Forget to Take a Dayquil Dose?

DayQuil is a drug you can take as needed, and you are not required to take it regularly. If your doctor has prescribed a dosage regimen for you and you forget to take a dose, take it as soon as you recall.

If your next dosage is approaching, skip the missed dose and take medicine on the next scheduled dose. Finally, do not double your next dose to make up for the missing one.

DayQuil Adverse Reactions

How long does Dayquil remain in your body?
DayQuil, like most drugs, can have negative effects. Many of these adverse effects may not necessitate medical treatment, but you should be aware of them. The adverse effects normally fade away when your body adjusts to the medication.

Common Adverse Reactions

  • Lightheadedness
  • Drowsiness
  • Dizziness
  • Stomach Ache
  • Nausea
  • Vomiting
  • Nervousness
  • Sleeping problems

Avoid eating grapefruit or drinking grapefruit juice if you’re on DayQuil. It has been shown that eating grapefruit while taking dextromethorphan (an active component in DayQuil) can raise dextromethorphan levels in the body. As a result, the negative effects of DayQuil, such as disorientation and anxiety, are exacerbated.

Other Negative Effects

The following are less common but more severe adverse effects:

  • 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 are uncommon, if you have any of them while taking DayQuil, get emergency medical assistance immediately.

How long does DayQuil last again? We explained that DayQuil has a four-hour duration. And, if the version of DayQuil you’re taking contains Dextromethorphan, the cough treatment will persist for around 6 hours. DayQuil remains in your system for 24 to 36 hours before being removed.

Consult a doctor if you continue to have adverse effects 24 to 36 hours after your last dosage of DayQuil, as the medication should be out of your system by this time.

How to Take DayQuil Correctly

  1. Always follow the manufacturer’s instructions.

DayQuil’s package label includes dosage directions. Follow the directions on the label or as directed by your doctor. Do not take less or bigger amounts than what is prescribed. When your symptoms have subsided, stop taking DayQuil.

Take for no more than 7 days. Consult your doctor if you still have a fever after three days, discomfort after seven days, develop a rash, or your symptoms worsen.

  1. Make use of the measuring spoon or cup that came with it.

The DayQuil liquid will be packaged with a measuring spoon or a medication cup. Use this to measure your liquid DayQuil instead of a regular spoon. Finally, if you misplace your medicine cup, contact your pharmacist for a replacement.

  1. Notify Your Doctor If You Are Having Surgery or Other Medical Procedures

Inform your doctor if you are taking DayQuil or have taken it within the previous two days. DayQuil may interfere with other drugs you will need after surgery.

  1. Proper Storage

DayQuil should be properly stored. Keep moisture and heat at bay. Also, avoid storing it in the freezer.

DayQuil Frequently Asked Questions

What Drugs Should You Avoid While Taking DayQuil?

Some drugs should be avoided when using DayQuil because the active substances (such as acetaminophen) in DayQuil can interact with them. These interactions have the potential to alter how the medicine works as well as its efficacy. They may also raise your chances of suffering from more severe side effects.

Acetaminophen Interacts with the Following Drugs:

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

DayQuil also includes phenylephrine and dextromethorphan, which interact with monoamine oxidase inhibitors, generally known as MAOIs. MAOIs remain in your system for around two weeks, so if you’ve taken them in the previous two weeks, there may still be medication interactions.


  • Isocarboxazid
  • Phenelzine
  • Selegiline
  • Tranylcypromine

Is DayQuil a safe medication?

For the most part, DayQuil is a safe medicine to use. However, if you have any of the following medical issues, you should avoid them. If you have any of the following medical problems, see your doctor before using DayQuil:

  • Obstruction in your stomach or intestines
  • Cardiovascular disease
  • Their blood pressure is too high.
  • Diabetes
  • The ailment of the Liver
  • Thyroid Disorder
  • Prostate enlargement that makes urinating difficult

Is it possible to abuse DayQuil?

DayQuil, like other medicines, can be abused. It is not suitable for all forms of cough. DayQuil should not be used to treat a productive cough or a cough that causes you to cough up mucus. Also, avoid using dayQuil if you have any of the following conditions:

Asthmatic cough, smoker’s cough, chronic bronchitis, or emphysema cough

Your doctor knows how to address these illnesses by providing a different medication.

DayQuil includes dextromethorphan, a commonly abused medication. It should be noted that too much dextromethorphan might cause hallucinations and, at extremely high dosages, death.

Also, remember that DayQuil should only be used in safe doses. The appropriate dose may be found on the product label.

What Happens If You Take Way Too Much DayQuil?

The acetaminophen in DayQuil might harm your liver if you take it too frequently. You must avoid consuming acetaminophen or any other drug that includes acetaminophen while taking DayQuil.

This can result in an acetaminophen overdose. Also, don’t take more than 4 doses of DayQuil in 24 hours, and don’t take it for more than 7 days.

If you take too much DayQuil, contact your local poison control center. If you know someone who has taken too much DayQuil, contact 911 immediately and seek medical assistance for the person.

What Should You Avoid If You Take Dayquil?

Do not use Dayquil with an acetaminophen-containing medication (either over-the-counter or prescription). Never take more than the recommended dosage.

Do not consume three or more alcoholic beverages daily while taking this product. If you combine Dayquil with other medications, the effects may change, increase, or decrease. As a result, it is essential to consult with your doctor.

How Should DayQuil Be Stored?

DayQuil should be kept away from light and moisture. Keep DayQuil away from children and pets, just as you would any other medication. For storage instructions, read and follow the product label.

When your DayQuil supply runs out, talk to your pharmacist or a local trash disposal firm about how to properly dispose of your medication. Do not flush or spill any medications down the toilet or the drain.


The effects of DayQuil continue for around 4 to 6 hours. DayQuil Cough can be used for up to 8 hours. The greatest action of DayQuil containing Dextromethorphan, a cough medicine, lasts roughly 6 hours.

This is why the dose on product labels ranges from 4 to 6 hours. DayQuil remains in your system for 24 to 36 hours before being removed.

DayQuil is a drug that is used to treat multi-symptom colds and flu. DayQuil’s powerful components alleviate your symptoms and make you feel better.

To take DayQuil safely, follow the instructions we provided. If you’re still unsure, talk to your doctor before using DayQuil.


Editorial Staff

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