The Dangers of Mixing Alcohol and Dayquil

Published On: December 13, 2022

It is quite common for people to struggle with colds and flu during the winter months and many people suffer from irritating symptoms such as a blocked or running nose, headaches, a sore throat and coughing fits.

To combat these symptoms many people turn to pharmaceutical products such as Dayquil to help alleviate the symptoms so they can get on with their daily activities with minimum inconvenience.

However, when examining current medical research it is apparent that people should adopt a degree of caution when taking Dayquil, particularly people who drink a lot of alcohol as Dayquil contains chemicals that can interact negatively with alcohol and cause unpleasant and dangerous symptoms. (4,7)

What is Dayquil?


Dayquil is an over-the-counter pharmaceutical product that helps counteract the negative symptoms associated with colds and the flu. It is referred to as a combination medicine and contains ingredients that combat fever, pain, nasal congestion and coughs.

Its main chemical constituents are acetaminophen, phenylephrine and dextromethorphan.

Dayquil does not tend to produce any symptoms associated with drowsiness as it is designed to be used during the day so that people can have some sort of relief from their cold/flu symptoms and get on with their daily activities.

There are three predominant chemicals in Dayquil that anyone using the medicine needs to be aware of as they can cause significant negative reactions when consumed alongside alcohol, these chemicals are acetaminophen, dextromethorphan and phenylephrine. (4,5)

Medical professionals recommend taking the pharmaceutical product for no longer than 7 Days, but ideally, it should be taken for the shortest time possible.


Acetaminophen is a form of paracetamol which people take to help relieve pain, people need to urge caution when taking just this medicine on its own regardless of their alcohol consumption as taking too much of a product containing paracetamol can damage the liver.

The general medical advice for taking paracetamol is not to exceed 4 doses which is equivalent to 8x500mg tablets in a 24-hour period. (3,4)


Dextromethorphan is the active ingredient in Dayquil which can suppress any unpleasant coughing fits that may be part of people’s cold or flu symptoms. It works by limiting activity in the area of the brain that stimulates the mechanisms associated with the act of coughing.

However, Dextromethorphan itself has been a drug that has been known to be abused recreationally over the years, primarily for its euphoric effects and to experience the visual and auditory hallucinations, and sensory experiences it provides for the user.

However, when dextromethorphan is mixed in with alcohol it can generate certain effects on the nervous system such as drowsiness, and dizziness and greatly limits our ability to focus for any significant period.

As it affects our cognitive abilities it may also affect our judgement which may lead to poor decision-making. This means people who are driving or operating mechanical equipment are at risk of placing themselves in grave danger.


The phenylephrine element in Dayquil is included for its ability as a decongestant and therefore relieves blocked nasal passages and alleviates sinus congestion when patients have a cold or flu.

However combing alcohol with Phenylephrine can lead to several unpleasant symptoms which if at their most severe can be life-threatening, these symptoms include; sluggishness and lethargy, dizziness, seizures, and cardiovascular and respiratory problems which can result in death.

Paracetamol should be taken with caution

pills in bottle

Regardless of alcohol consumption. there are many cases each year of people taking too much paracetamol (acetaminophen) and becoming seriously unwell.

Paracetamol has a very toxic effect on the liver and there is a strong likelihood that taking more than 4 doses in 24 hours can seriously damage your liver. (4,7)

The role of the liver in the human body


The liver is involved in several hundred biological processes that enable us to function each day, this includes:

  • Eliminating waste products from the body.
  • Converting glucose to glycogen to give us energy.
  • Getting rid of harmful chemicals from the blood.
  • Removing bacteria from our bloodstream and releasing chemicals to boost our immune system.

Both alcohol and acetaminophen are metabolised by the liver which puts this organ under pressure when it is required to process the chemical properties of these substances close together.

Scientific research reveals that a person can do serious damage to their liver if they consume alcohol within a few hours of taking Dayquil. 

This risk increases the longer they take Dayquil and the higher the volume of alcohol they consume. (2)

All medicinal products have the potential to interact negatively with alcohol

Pill doses

Alcohol is a powerful central nervous system depressant and any drugs whether prescription based-drugs or over-the-counter medicine have the potential to interact with alcohol and produce negative consequences.

It is always safe to assume that consuming alcohol whilst taking anything medicinal will be problematic due to the nature of drug interaction science. (3)

Interaction effects generated by mixing alcohol and Dayquil

Cosmopolitan cocktail on a napkin

Scientific research has shown that when alcohol is consumed within a short period of taking phenylephrine individuals will experience confusion, have dizzy spells, become light-headed, experience problems with their balance and find that their breathing will become more laboured.

It has also been known for people to collapse and become unconscious and not wake up for some time, indicating a very powerful interaction between the two substances.

Several medical studies have found that combining alcohol and the paracetamol compounds in Dayquil can significantly increase the risk of kidney disease as well as liver damage.

There is also a risk of overdose when mixing these substances, an overdose occurs when the body is unable to process the full content of any substance consumed quickly enough and the respiratory system breaks down and stops working.

This also means there are a lot of toxic chemicals left inside the body that have not yet been eliminated. (3,5)

Overdose signs associated with combing alcohol and Dayquil:

  • People will experience hallucinations.
  • They may appear confused.
  • They will have feelings of paranoia.
  • They may suffer from delusions.
  • Feeling nauseous.
  • Susceptible to bouts of vomiting.
  • Abdominal discomfort/pain.

If you know that people have been drinking alcohol while they are taking Dayquil and have any of the above symptoms then it is imperative that you contact the emergency medical services as soon as possible as they require urgent medical attention.

It is clear that all the significant chemical components in Dayquil are capable of generating a negative outcome when combined with alcohol and pose a health risk for any individual who consumes alcohol within hours of taking Dayquil. (3,6)

So it would be unwise to consider drinking any alcohol at all whilst on a course of Dayquil

A summary of the physical effects of combining Dayquil and alcohol

  • An upset stomach.
  • Intestinal bleeding and the development of open sores in the stomach (ulcers).
  • Damage to the liver due to high levels of toxicity in the body.
  • Irregular cardiac activity, rapid heartbeat.
  • Risk of overdose.
  • Feeling drowsy.
  • Dizziness and loss of balance.
  • Difficulty focusing on tasks.
  • Developing a fever.
  • Bleeding or bruising on your body.
  • Feeling nauseous.

It is difficult to predict the exact nature of drug interactions

black out 1

There is a great deal of biological and social variation between people so basing a decision on whether to drink alcohol whilst on a course of Dayquil with someone else’s experience could end up having severe health implications for you.

For example, a single unit of alcohol can stay in the body for approximately three hours and if Dayquil is taken within this 3-hour window then it could interact with the alcohol already present in your body.

The effects of Dayquil, however, can stay in the body for 3-6 hours and if alcohol is consumed within this period of time it could cause a negative interaction and produce unpleasant and serious symptoms.

It is very difficult to predict what the interaction effects would be for any individual person as everyone has a different threshold and tolerance level for each substance and there are many other factors including age, gender, underlying health and diet that also need to be considered. (1,3)

Is it OK to just have a couple of drinks when taking Dayquil?

teen drink 2

This cannot be stated with any certainty due to the individual differences between us all, some medical research studies have suggested that it is OK to have one or two drinks while taking Dayquil, but it is unsafe to rely on this advice as each person has unique personal circumstances that set them apart from others.

Without knowing all of these factors it cannot be guaranteed that a person having one or two alcoholic drinks when taking Dayquil will experience no adverse reactions.

The easiest advice would be not to drink alcohol at all whilst taking Dayquil and then you can be sure there will be no negative consequences.

Binge drinking and Dayquil

woman drinking 2

The act of binge drinking alone can cause significant health problems for people as a result of alcohol poisoning. Binge drinking is defined as drinking 5 alcoholic drinks (10-15 units) in 2 hours for men and 4 drinks (7-11 units) per hour for women.

This would mean their blood alcohol concentration is above 0.08%, the more alcohol people consume in that time the greater their chances of developing alcohol poisoning which can lead to liver failure and overdose.

Couple this high alcohol intake with the use of Dayquil to cope with the effects of a cold or flu and people would place themselves in an extremely vulnerable situation where they could become seriously ill and die within a much shorter period.

Important Factors to consider


  • AgeAs people reach 40 their ability to metabolise alcohol will drop significantly but people over 65 are at a higher risk of developing a serious health condition due to the interaction effects generated by drinking alcohol and taking Dayquil as their bodies will be less efficient at breaking down alcohol.
  • Underlying healthPeople with underlying medical conditions (e.g .asthma, diabetes) will be more affected by any interaction effects.
  • Sex Females are more at risk than males of experiencing a negative interaction as they have less water in their body to dilute alcohol than men.
  • Tolerance to alcohol Some people can metabolise alcohol more efficiently and over time their body has become accustomed to processing alcohol.
  • Other medicationsTaking other medications can complicate matters even further, depending on the type of medication.
  • Liver healthThe general health and efficiency of a person’s liver is an important factor, the healthier a person’s liver the less likely they are to be negatively affected.

It’s always best to check with your GP as they have access to your medical history and can advise you accordingly, although the only way to be sure you will not experience any ill effects is to avoid alcohol completely during the time you are taking Dayquil.  (1,3,5,7)

Heavy, excessive drinkers should avoid Dayquil

Medicated detox

Some medical researchers propose that heavy, long-term drinkers who would probably be diagnosed as having an alcohol use disorder would be in serious danger of damaging their liver if they started taking Dayquil, even at the recommended dose levels.

It is unlikely that your doctor would recommend that you take Dayquil if he/she was aware that you are struggling to control your alcohol use, as the risk of coming of experiencing negative interaction effects would be quite high.

However, Dayquil is an over-the-counter product which you can obtain without a prescription so it is important to be aware of this interaction and avoid taking Dayquil if you are feeling under the weather and know that you are unable to stop or limit your alcohol intake.

Your GP can advise you of alternative pharmaceutical products that you would be better off taking or at least advise you on how to take Dayquil if they thought it was safe for you to do so.

Patients in rehab

Woman support

Patients receiving inpatient rehab for alcohol use disorder are probably OK to take Dayquil as they will not be consuming any alcohol during their spell in rehab due to the close monitoring and constant care they receive in these treatment centres.

However, it is probably wise to check with the rehab centre medical team who have access to your medical records before you start taking the product as there may be other reasons why it may be unsafe for you to take Dayquil.

You may be advised to take lower doses within a 24-hour period, but this depends on how far down the treatment/recovery process you are.

Heavy alcohol users have poorer health in general


Anyone diagnosed with an alcohol use disorder or who has been drinking heavily over the long term is more prone to being unwell as their heavy alcohol use will have decreased the efficiency of their cardiovascular, respiratory and immune systems.

This means they are more likely to be unhealthy, and less able to fight off environmental pathogens that cause influenza and the common cold.

Due to their inability to stop or reduce their alcohol intake, the best course of action would be for them to deal with the symptoms of the cold or flu without the assistance of  Dayquil.


(1) Ghosh, al (2020) The Role of Alcohol Consumption on Acetaminophen Induced Liver Injury: Implications from A Mathematical Model. available@The Role of Alcohol Consumption on Acetaminophen Induced Liver Injury: Implications from A Mathematical Model | bioRxiv

(2) John Hopkins Medicine University (2022) Liver: Anatomy and functions. Available@Liver: Anatomy and Functions | Johns Hopkins Medicine

(3) National Institute on Alcohol Abuse and Alcoholism (2022) Harmful interactions: Mixing alcohol with medicine.available @ Harmful Interactions | National Institute on Alcohol Abuse and Alcoholism (NIAAA) (

(4) National Prescribing services (2004) Alcohol and Paracetamol. available@ Alcohol and paracetamol – Australian Prescriber (

(5) Prescott, L. (2000) Paracetamol, Alcohol and the Liver. available@paracetamol, alcohol and the liver – PMC (

(6) Standford University (2022) Alcohol Overdose and Poisoning available@Alcohol Overdose/Poisoning | Vaden Health Services (

(7) Yoon, E. et al (2016) Acetaminophen-Induced Hepatoxicity: A Comprehensive update. available@Acetaminophen-Induced Hepatotoxicity: a Comprehensive Update – PMC (

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