How long does DayQuil last?

DayQuil treats cold and flu symptoms for approximately four hours.

DayQuil Cough provides up to 8 hours of cough relief.

How long it stays in your system?

Most DayQuil users should expect to have eliminated the pharmacologically active ingredients from their systems within 24 to 48 hours of taking it

What is DayQuil?

If you are familiar with the manufacturer Procter & Gamble, then you have probably also heard of its brand “Vicks” DayQuil, an over-the-counter (OTC) medication is sold under this brand.

DayQuil is almost similar to NyQuil, its sister compound, but the former is to be taken during waking hours, while the latter is for nighttime use. It has grown in popularity because of its ability to alleviate unwanted symptoms without having a negative impact on one’s cognitive function and without causing drowsiness.

Among the symptoms it alleviates are fever, nasal congestion, minor aches, and other symptoms of the common cold.

However, some users may experience side effects such as a slight brain fog,  even, after several days of use. This raises the issue on how long DayQuil lasts in the system.

What is NyQuil?

NyQuil is mentioned earlier, because it is the sister product of DayQuil. The only difference is that it should be taken at night. The formulation is the same, instead for an additional ingredient, the antihistamine, Doxylamine. As a result, it can cause sleepiness.

What is DayQuil for?

DayQuil has around 5 different formulations, each created with different set of ingredients to address specific concerns and symptoms.

The commonality among these formulations is that they contain any or a mix of acetaminophen, dextromethorphan (DXM), guaifenesin, phenylephrine, and oxymetazoline.

The last two function as decongestant.

The acetaminophen, dextromethorphan, and guaifenesin act as analgesic/fever reducer, antitussive (cough suppressant), and mucus expulsion aid, respectively.

Different DayQuil Formulations

As mentioned above, different formulations contain one or a mix of the ingredients. Here are the available DayQuil formulations:

  • DayQuil Cough – contains Dextromethorphan only
  • DayQuil Mucus Control – contains both Dextromethorphan and Guaifenesin
  • DayQuil Cold and Flu – contains Acetaminophen, Dextromethorphan, and Phenylephrine
  • DayQuil Severe Cold and Flu – the same ingredients as DayQuil Cold and Flu, plus Guaifenesin

Ingredient’s required time to be eliminated from the system

How long does DayQuil last in your system? Here is a thorough calculation of how long it takes for each ingredient to be eliminated from the system:

  • Acetaminophen- 22 hours
  • Phenylephrine- 17 hours
  • Guaifenesin- 6 hours, shortest elimination time
  • Dextromethorphan- 33 hours, longest elimination time

Hence, from this ingredient’s elimination time, for DayQuil to be totally eliminated from your system, you’ll need about 24 to 36 hours. Moreover, the effect of DayQuil lasts for about 4 to 6 hours.

Dayquil Ingredients in detail


  • A known formula for cough medicines
  • The same chemical family as morphine, works as a sedative and cough suppressant
  • Works by numbing the throat and senses, in recommended dosage
  • When taken in excess, side effects may include hallucinations and dissociations


  • Works as a decongestant
  • To be used as nasal spray
  • Reduced efficiency when taken orally, based from studies


  • Commonly known as paracetamol
  • Reduces fever
  • Also relieves moderate pain


  • Helps make mucus thin to enable you to easily cough it out

How often should I take DayQuil? Recommended dosage for DayQuil

Before reading the dosage, DayQuil can come in LiquiCaps and Liquid form. If symptoms still persist after two days of taking DayQuil, it is best to consult your doctor.

LiquiCaps are the capsule versions of DayQuil, meaning these contain liquid inside.

Liquid form is also available as another option.

For children below 4 years old

  • DayQuil should not be administered.

For children (6-11 years old)

  • LiquiCaps is not recommended
  • Liquid form is to be taken every 4 hours at 15 ml, with no more than 4 doses within 24 hours.

For 12 years and above

  • LiquiCaps to be taken every 4 hours at two capsules, with no more than 4 doses within 24 hours
  • Liquid form to be taken every 4 hours at 30 ml. With no more than 4 doses within 24 hours

Dosage reminders

Take the DayQuil when needed. If you are on a dosing schedule as prescribed by your doctor, and you missed it, take it as soon as you remember. Do not add more DayQuil to your next dose to make up for your missed dose.

Possible side effects of DayQuil

Some may experience side effects after taking DayQuil, just like when taking other medicines. These side effects go away on their own as your body adjusts to the components. These mild side effects do not warrant medical attention. Some of these include:

  • Dizziness and lightheadedness
  • Drowsiness
  • Nausea and or vomiting
  • Nervousness
  • Sleeping difficulties
  • Stomach Pain

Some severe side effects yet less common are:

  • Difficulty breathing and/or swallowing
  • Hives, rashes and/or itching
  • Red skin which peels or blisters
  • Swelling of face (including tongue, throat, lips), hands and feet

Additional precautions

  • DayQuil takes 24-36 hours to be eliminated from your system. If after that period of your last dosage and you still experience side effects, consult your doctor.
  • If you experience uncommon side effects, seek medical attention right away.
  • Avoid consuming grapefruit or its juice when taking DayQuil as it can increase dextromethorphan in your system, leading to nervousness and dizziness.

Steps to properly take DayQuil

Follow the doctor’s prescription/product label instruction

Use it is directed by your doctor or as what is instructed on the product label. Do not take less or more than what is required, and stop taking it once symptoms are gone. DayQuil should not be taken for more than 7 days. If fever and pain still persist after 3 and 7 days respectively, seek medical attention immediately. Never hesitate to consult your doctor if you experience side effects such as rash.\

Use the measuring tool that comes with your medicine

Never use an ordinary spoon when taking your medicine. Either you get a medicine cup or a measuring spoon for your DayQuil. If ever you lose the measuring tool that comes with it, ask or buy again from the nearest pharmacy.

Reveal your medical history to your doctor

Whether you underwent surgery or other medical procedures, or if you have a history of allergies, tell it to your doctor. In this case, your doctor would know of possible contraindications that it may have with DayQuil.

Practice proper medicine storage

Follow the storage instructions indicated in the product label. Never store it in a freezer or in places exposed in direct heat or moisture.

Factors that affect DayQuil’s elimination rate from your system

On average, those who take DayQuil expect it to be eliminated from their system in about 24 to 48 hours. However, there are several factors that hasten or slow down this process. Among these are:

Individual/personal factors

People can have different rates of metabolizing and eliminating DayQuil from their systems even if they are administered the same amounts. This could be caused by:


It was scientifically proven that those over the age of 65 have an altered DayQuil component distribution compared to younger adults, leading to impairment in its elimination to the system. Hence, a person’s age has an effect on its DayQuil elimination and metabolization.

Moreover, the older the person, the more his renal and hepatic function declines, leading to extended time needed for DayQuil elimination from the system. Decreased glutathione levels are also observed as a person ages.

Body mass and fat percentage

It was found out that those with higher BMI can eliminate DayQuil from their system faster, compared to those with lower BMI because the former has better metabolization efficiency in terms of large doses. Body fat percentage is also another factor because most of DayQuil’s components are hydrophilic.

Meaning, the higher the body fat percentage a person has, the less it will retain DayQuil’s hydrophilic ingredients. Those with lower body fat percentage have more water in their tissue, hence, they retain more of the DayQuil’s ingredients.

Heredity and Genetics

The CYP450 (cytochrome P450) isoenzymes are the ones responsible for DayQuil’s components metabolization, and genetics play a huge part in this hepatic function.

Some individuals are born with alleles capable of decrease in the CYP2D6 isoenzyme function, hence they retain dextromethorphan for a longer period of time compared to those with average CYP2D6 function.

For poor CYP2D6 metabolizers, which comprises around 3 to 10 percent of the population, dextromethorphan may stay in their system for around 5 days after the last intake. On the contrary, rapid metabolizers of CYP2D6 can eliminate dextromethorphan in just less than 2 days from their system. Thus, heredity affects the metabolism of dextromethorphan.

Individual’s glutathione levels

Acetaminophen is one of the contents of DayQuil, and its elimination is affected by an individual’s glutathione levels. Lower glutathione levels mean that your acetaminophen elimination is slower.

It is because before elimination acetaminophen is converted to NAPQI, a toxic metabolite because of its conjugation with sulfates and glucuronides. Low glutathione levels impair NAPQI elimination.

Hepatic impairment

An individual having hepatic impairment could lead to DayQuil half-life elimination exceeding up to 4 hours. Meaning, if someone has hepatic impairment, it may take them a full day in order to fully eliminate from the system the acetaminophen and dextromethorphan.

The latter needs CYP2D6 isoenzymes to metabolize and the presence of these enzymes decrease along with hepatic impairment. Hence, in terms of dextromethorphan elimination for individuals with hepatic impairment, it could take more than 5 days.

Basal metabolic rate (BMR)

The higher the BMR of a person, the faster they can burn energy and eliminate substances even when at rest compared to their counterparts with lower BMR. Those with lower BMR have lesser energy burnt when at rest.

For instance, if someone has hyperthyroidism which optimizes BMR, they can easily metabolize drugs. The difference in DayQuil elimination is significantly evident for individuals with hypo and hyperthyroidism.

Kidney function

Kidney and or renal impairment can lengthen the elimination of DayQuil components from your system. The metabolites from acetaminophen and dextromethorphan could get accumulated in the kidney and could be reabsorbed and recirculated in the body.

If an individual has renal impairment, DayQuil could be retained in the system and there could be problems in eliminating it.

Urinary flow rate

The higher the urinary flow rate of an individual, the greater the amount of acetaminophen excreted. Hydration is one of the key factors that affect a person’s urinary flow rate, so the more often you hydrate yourself, the faster you can excrete the DayQuil components from your system.

Hence, a dehydrated person will have lower urinary flow rate, hence, DayQuil ingredients remain in the system for a longer period of time compared to their counterparts who are hydrated with a high urinary flow rate.

Amount intake

Your total daily dosage impacts your DayQuil elimination. The higher the dosage and the more frequent you take it means that it needs a longer time to be eliminated from your system.

The higher the dosage, the lesser the metabolism and elimination efficiency is because of the bigger quantity of exogenous substances needed metabolization. With a higher dosage also comes a greater number of metabolites formed and accumulated which reduces the renal excretion efficiency.

The capability of renal excretion is limited only to a certain amount of ingredient at a specific amount of time. Hence, the lower the dosage, the faster and more efficient your metabolic and renal function works, and the faster you can eliminate it from your system.

Intake frequency

The more frequent you take DayQuil and the longer the term is, the more time it needs to be fully eliminated from your system. If you frequently take it in a single day, chances are your body needs to metabolize it even if it has not yet completely processed the previous intake.

This can lead to DayQuil component accumulation in the plasma, which could reduce your renal excretion and hepatic metabolism. Gaps in between each intake allow your system to avoid this accumulation, and fully eliminate the previous dose before processing the new one.

Hence, if you take it on an inconsistent basis, you get faster elimination compared to someone who takes it several times every day. The same is true for short-term use.

Short-term DayQuil users have a faster elimination rate compared to their long-term user counterparts as the latter already have lots of accumulated components in their system.

Drugs co-administered with DayQuil

Drugs that interact with DayQuil’s ingredients when co-administered can affect the elimination rate. For instance, “inhibitor” drugs that affect the CYP2D6 isoenzymes’ functions can alter the dextromethorphan elimination, making it longer.

Examples of these inhibitors are Bupropion, Cinacalcet, Fluoxetine, Paroxetine, Quinidine, and Ritonavir. On the other hand, there are also CYP2D6 inducers such as Dexamethasone, Glutethimide, and Rifampicin. These can hasten the dextromethorphan elimination from your system.

How to hasten DayQuil elimination from your system

These are some suggestions which can help you fully eliminate DayQuil from your system. Feel free to seek the advice of a medical professional prior to following these tips.

Take activated charcoal

An activated charcoal is a supplement which binds to chemicals and endotoxins that are circulating from your body and are unmetabolized.

Because of activated charcoal’s negative electrical charge, it binds with the remnants of DayQuil’s components such as acetaminophen and NAPQI. This way, eliminating these substances from the body is hastened.

Calcium-D-Glucarate supplementation

Calcium-D-Glucarate helps with the detoxification of your renal pathways because it acts as an inhibitor to one of DayQuil’s ingredients, the beta-glucuronidase. Hence, it detoxifies your renal pathways which could be blocked by the accumulation of toxins from DayQuil and other dietary and environmental contaminants.

Glutathione intake

Glutathione helps in conjugating NAPQI, and this is produced by the liver. The naturally-produced glutathione from your liver may not be enough to handle the acetaminophen content in DayQuil, especially if you are a heavy user.

That is why, taking additional Glutathione to aid your body’s natural; processes is a good way to better eliminate acetaminophen.

Urinary flow rate

Your urinary flow rate is directly proportional to your rate of DayQuil elimination. The faster the urinary flow rate, the faster you can eliminate acetaminophen and other DayQuil ingredients.

The lower the urinary flow rate, the more time you need for elimination. Urinary flow rate is also related to a person’s hydration. If you are dehydrated, you’ll have lower urinary flow rate, hence, the lower the rate of elimination and the longer it will take.


Is it okay to drink alcohol after taking DayQuil?

Both DayQuil and alcohol have sedative properties, and should not be taken together, otherwise it could lead to a variety of severe medical injuries such as liver damage. Moreover, alcohol can trigger and worsen your cold and other symptoms as this is an immune system suppressant.

How much time should I wait before drinking alcohol after taking DayQuil?

Elimination of the ingredients in alcohol and DayQuil varies per person. On average, it is already fine to drink alcohol after 4-6 hours of your last DayQuil intake. By that time, the Dayquil is already not active in your system. If you are planning to take DayQuil after drinking alcohol, wait for 3 hours after your last alcoholic drink. This way, you’ll avoid the possibilities of these two causing a negative reaction. Lastly, never ever mix DayQuil and alcohol.

When should I not take DayQuil?

If you have heart, liver, and thyroid disease, diabetes, high blood pressure, blockage in your intestines/stomach, and enlarged prostate leading to urinating difficulties, it is best to consult your doctor before taking DayQuil.

How should I store the DayQuil?

Never expose the DayQuil to direct light and moisture. Check the product label for the detailed instruction on appropriate storage. Also, place it in an area away from children’s reach. Once expired. Never flush it in the toilet or the drain. Ask your local waste disposal company on the appropriate ways to discard the product.