Nyquil Side Effects

Estimated reading time: 27 minute(s)

NyQuil is possibly one of the most common medications people use to manage nasty colds and flu. As harmless as it seems, have you ever wondered why the cashier at a convenience store or pharmacy asks for an ID when you go purchasing it or any other cold medication? This is because some of these medications, including NyQuil, contain certain ingredients that may cause side effects, especially in high doses.

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NyQuil, just like other cold medications, may seem like a harmless everyday remedy to manage cold and flu but still carries the potential to trigger side effects, like allergies, rash, blurry vision, stomach aches, and more. It is essential to familiarize yourself with these side effects and understand how to keep them at bay through proper drug use.

What is NyQuil, and What Does it Include?

NyQuil is a common and trendy over-the-counter medication used to treat the common cold, flu, and other similar allergies and illnesses. Manufactured and sold by a U.S. medicine company called Vicks, this medication provides temporary relief for headaches, runny and stuffy nose, coughing, fever, sneezing, and sore throat. NyQuil also offers quick relief from cold symptoms, allowing people to sleep peacefully through the night. Despite providing temporary relief for cold and flu, the company does not advertise it as a cure.

The medication generally has a good safety profile and is considered effective and safe for children and adults over 6. However, certain ingredients in NyQuil can lead to a few side effects. Before understanding the possible NyQuil side effects and associated risks, knowing what the medication includes is essential.

The following are the ingredients present in NyQuil:

Dextromethorphan HBR

This ingredient works as a cough suppressant to provide relief against bouts of cough by suppressing the cough center in the brain. Despite the high efficacy, dextromethorphan carries certain risks and side effects, especially if you take it in high doses. 

Doxylamine Succinate

This sleeping aid provides users with a drowsy and relaxed feeling. Categorized as an antihistamine, it also reduced cough attacks due to allergy. 

Citric Acid

Citric acid acts as a beneficial flu killer.

Propylene Glycol & Polyethylene Glycol

Both propylene and polyethylene glycol are chemicals commonly used in medications as thickeners. Their consistency is between water and honey, and they help make syrups maintain their consistency.

Sodium Citrate

Sodium citrate has been added to NyQuil’s composition to balance the ingredients and maintain an optimal acid-base concentration. The ingredient also acts as an anticoagulant and supports buffering.


While the manufacturing company negates adding any flavor, many experts believe that it does include it, at least in some quantities.

High Fructose Corn Syrup

The purpose of adding this ingredient to a supplement is to make it easier to swallow.

Potential NyQuil Side Effects and Risks Explained

NyQuil is generally safe, especially if used properly. The most common side effects it may trigger in a user are usually minor and may not require any medical attention. Some of these side effects include:

  • Blurry vision
  • Stomach pain
  • Vomiting and nausea
  • Lightheadedness
  • Drowsiness
  • Dizziness
  • Excitability and nervousness
  • Dry nose, mouth, or throat

It is essential to stick to the instructions written on the bottle every time a person uses NyQuil and avoid taking too much of it. Those who keep using the medication with or without an indication are at risk of liver damage and may even lose consciousness on several occasions. Additionally, it is also essential to abstain from drinking alcohol while using NyQuil in addition to combining it with other medications containing acetaminophen.

Some people, especially those allergic to one or more of its core ingredients, may develop a NyQuil allergy. Some common signs of an allergic reaction to those medications include:

  • Itchiness
  • Rash
  • Hives
  • Difficulty breathing and swallowing
  • Swelling in throat, mouth, and face

NyQuil Side Effects: Is an Overdose Possible?

Many people believe that over-the-counter medications for colds and flu, like NyQuil, cannot cause any serious side effects. However, as with all other drugs, using NyQuil in the correct dosage is essential. This is because it contains chemicals like antihistamines which can have profound implications when taken in high doses.

Too much NyQuil can lead to overdoses, triggering dangerous symptoms such as coma, cardiac arrest, seizures, respiratory stress, and even death. Some other side effects of taking too much NyQuil or other sleep medications include the following:

  • Headache
  • Depression and anxiety
  • Drowsiness
  • Confusion
  • Dizziness
  • Nausea and vomiting
  • Mild tremors
  • Stomach cramps
  • Increased heart rate
  • Low blood pressure
  • Blurred vision
  • Loss of balance

NyQuil Use and the Risk of Addiction

An individual who uses NyQuil correctly is very less likely to become addicted to it. On the other hand, misusing this apparently safe drug can cause dependence, eventually leading to addiction. Someone may misuse the medication by taking too much of it or using it for the wrong reasons, such as for treating chronic bronchitis or asthma. Some people may even start relying on NyQuil for recreation and become dependent on it daily. Remember that NyQuil is only meant to treat short-term symptoms and does not cure any long-term health issues. It can also not treat insomnia and must never be used to fall asleep at night.

Once someone becomes dependent on NyQuil, they may struggle to fall asleep without it, even when not sick. Such people also commonly develop uncomfortable symptoms when they stop using this medication. These uncomfortable symptoms engage them in repeated use, due to which their dependence quickly escalates to addiction. Once addiction sets in, such people may develop proper physical withdrawal symptoms compared to the ones seen in other addictions, like cocaine and methamphetamine.

Some common withdrawal symptoms seen in people with NyQuil addiction include the following:

  • Anxiety
  • Insomnia
  • Depression and anxiety
  • Strong cravings to use NyQuil
  • Chills
  • Tremors and shakiness
  • Nausea
  • Restlessness
  • Stomach ache

People with NyQuil addiction may find recovery hard, mainly because of their overwhelming withdrawal symptoms. Fortunately, help and support are available at rehabilitation centers to escape the withdrawal cycle and minimize relapses.

NyQuil and Dextromethorphan Abuse

Many people, especially those in their teenage years, commonly use NyQuil to get high. This NyQuil high is due to one of its ingredients called dextromethorphan which carries mild-altering properties. Dextromethorphan is currently an ingredient in more than 70 medications and acts as a cough suppressant in smaller doses without posing any risk of side effects. It has also not been classified as a controlled substance because of a very low threat risk.

That said, dextromethorphan can directly affect the brain, meaning using it in excessive amounts may lead to euphoria and hallucinations. In other words, its effects can be comparable to those of illegal mild-altering substances like marijuana and cocaine. Since NyQuil is much easier to obtain than other recreational drugs, more people are likely to use it for pleasure and euphoria. Abusing dextromethorphan-containing drugs for euphoria is known as “robo-tripping” or “skittling.”

Using NyQuil for its dextromethorphan content can lead to severe consequences and a range of side effects similar to the ones experienced with PCP, an illegal hallucinogen. Dextromethorphan also impairs judgment and coordination, making driving a dangerous task. Additionally, combining it with a product containing antidepressants, alcohol, or acetaminophen, such as NyQuil, may harm the liver and cause seizures, heart attack, and even death.


Does NyQuil have antihistamines?

NyQuil contains three active ingredients: dextromethorphan, acetaminophen, and doxylamine. While the first and second ones relieve fever and suppress coughing, doxylamine is a type of antihistamine or anti-allergy medication that helps provide relief against sore throat, sneezing, and congestion.

Does NyQuil have codeine in it?

Contrary to what many people believe, NyQuil does not contain any codeine in it. It simply has paracetamol as a painkiller that usually poses no threat of addiction or severe health risks when taken in safe doses.

Is it bad to take NyQuil a lot?

While NyQuil can provide significant relief to most people, experts advise not to use it without a reason until there is an absolute indication. Taking too much NyQuil may lead to plenty of side effects, such as liver damage or loss of consciousness.

Can NyQuil cause side effects if I already have a medical condition?

Yes, it may not be safe to take NyQuil if you already suffer from certain medical conditions, such as:

  • COPD, asthma, cough due to smoking, chronic bronchitis, or emphysema
  • Kidney disease
  • Liver disease or cirrhosis
  • A strong history of alcoholism
  • Blockages in the intestines or stomach
  • Glaucoma
  • An enlarged prostate
  • Urinary problems

Will there be any NyQuil side effects if I take it to sleep when I am not sick?

It is best to avoid consuming NyQuil for sleep when you do not have flu or cold. The medication contains ingredients that may put you to sleep, such as dextromethorphan, but it also has certain other agents, like alcohol, that may interfere with sleep cycles. If the medication has previously helped you go to sleep and you are tempted to use it again, always contact a doctor first. Using it too much without any medical indication and for the sole purpose of sleeping well can even lead to NyQuil addiction.

What should I do if I suspect that I have overdosed on NyQuil?

If you suspect to have ingested more NyQuil than what’s safely indicated, watch out for specific signs suggestive of an overdose. The earliest signs of an overdose include nausea, vomiting, sweating, stomach pain, loss of appetite, weakness, and confusion. As time passes, you may develop additional symptoms like dark urine, yellowing of the skin and whites of the eyes, and pain in the upper stomach. Make sure to get in touch with the local poison control team and explain your concerns the minute you start noticing these symptoms in yourself or a loved one. The earlier you report the symptoms and seek help, the easier it is to manage the condition.

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