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 does it stay 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 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 hurting one’s cognitive function and causing drowsiness.

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

However, some users may experience side effects such as slight brain fog,  even after several days of use. This raises the issue of 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 of an additional ingredient, the antihistamine, Doxylamine. As a result, it can cause sleepiness.

What is DayQuil for?

DayQuil has five different formulations, each created with different 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 decongestants.

The acetaminophen, Dextromethorphan, and guaifenesin act as analgesic/fever reducers, antitussive (cough suppressant), and mucus expulsion aid.

Different DayQuil Formulations

As mentioned above, different formulations contain one or a mix of 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

Ingredients 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, for DayQuil to be eliminated from your system from this ingredient’s elimination time, 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
  • In the same chemical family, 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 a nasal spray
  • Reduced efficiency when taken orally, based on studies


  • Commonly known as paracetamol
  • Reduces fever
  • It also relieves moderate pain


  • It helps make mucus thin to enable you to cough it out easily

How often should I take DayQuil? The recommended dosage for DayQuil

Before reading the dosage, DayQuil can come in LiquiCaps and Liquid form. If symptoms 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.

The liquid form is also available as another option.

For children below four years old

  • DayQuil should not be administered.

For children (6-11 years old)

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

For 12 years and above

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

Dosage reminders

Take the DayQuil when needed. If you are on a dosing schedule as prescribed by your doctor and 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 other medicines. These side effects go away 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 swallowing
  • Hives, rashes, and 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 instructions.

Use it as directed by your doctor or as what is instructed on the product label. Do not take less or more than required; stop taking it once symptoms are gone. DayQuil should not be taken for more than seven days. If fever and pain persist after 3 and 7 days, 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

Tell your doctor whether you underwent surgery or other medical procedures or have a history of allergies. 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 places exposed to 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, several factors 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 exact amounts. This could be caused by:


It was scientifically proven that those over 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 affects its DayQuil elimination and metabolization.

Moreover, the older the person, the more his renal and hepatic function declines, leading to the 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 that those with higher BMI can eliminate DayQuil from their system faster than those with lower BMI because the former has better metabolization efficiency in large doses. Body fat percentage is another factor because most of DayQuil’s components are hydrophilic.

They mean that the higher the body fat percentage a person has, the less it will retain DayQuil’s hydrophilic ingredients. Conversely, lower body fat percentages have more water in their tissue. Hence, they retain more of DayQuil’s ingredients.

Heredity and Genetics

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

Some individuals are born with alleles capable of decreasing the CYP2D6 isoenzyme function. Hence they retain Dextromethorphan for a longer period than those with average CYP2D6 function.

For poor CYP2D6 metabolizers, which comprise around 3 to 10 percent of the population, Dextromethorphan may stay in their system for around five days after the last intake. On the contrary, rapid metabolizers of CYP2D6 can eliminate Dextromethorphan in less than two 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. Therefore, 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 with hepatic impairment could lead to DayQuil half-life elimination exceeding 4 hours. If someone has a hepatic impairment, it may take a whole day to eliminate the acetaminophen and Dextromethorphan from the system.

The latter needs CYP2D6 isoenzymes to metabolize, and the presence of these enzymes decreases along with hepatic impairment. Hence, in terms of dextromethorphan elimination for individuals with hepatic impairment, it could take more than five 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. Conversely, those with lower BMR have lesser energy burnt when at rest.

For instance, if someone with hyperthyroidism optimizes BMR, they can efficiently metabolize drugs. In addition, 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 accumulate in the kidney and 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 a critical factor affecting 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 a lower urinary flow rate. Hence, DayQuil ingredients remain in the system for longer than their hydrated counterparts 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, 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 because the more significant quantity of exogenous substances need metabolization. Higher dosage also comes with a more significant number of metabolites formed and accumulated, reducing renal excretion efficiency.

The capability of renal excretion is limited only to a certain amount of ingredients at a specific 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 eliminated from your system. If you frequently take it in a single day, your body needs to metabolize it even if it has not yet wholly processed the previous intake.

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

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

Short-term DayQuil users have a faster elimination rate than their long-term users, as the latter already have many accumulated components in their system.

Drugs co-administered with DayQuil

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

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 suggestions can help you eliminate DayQuil from your system. Feel free to seek the advice of a medical professional before following these tips.

Take activated charcoal

Activated charcoal is a supplement that binds to chemicals and endotoxins that are circulating in 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 detoxify your renal pathways because it acts as an inhibitor to one of DayQuil’s ingredients, 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 the liver produces this. However, 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 an excellent way to eliminate acetaminophen better.

Urinary flow rate

Your urinary flow rate is directly proportional to your rate of DayQuil elimination. Therefore, 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 a 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 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 acceptable 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 possibility of these two causing an adverse reaction. Lastly, never mix DayQuil and alcohol.

When should I not take DayQuil?

Suppose you have heart, liver, and thyroid disease, diabetes, high blood pressure, blockage in your intestines/stomach, and enlarged prostate leading to urinating difficulties. In that case, 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 detailed instructions on appropriate storage. Also, please 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 about the appropriate ways to discard the product.