NyQuil is an over-the-counter (OTC) medication used to treat symptoms of flu, colds, and other respiratory illnesses, including congestion, sneezing, and coughing. NyQuil has several active ingredients with different durations, typically lasting up to 6 hours.[1]
Learn more about NyQuil, how long its effects last, and how to use it safely.
What Is NyQuil?
NyQuil is the brand name for an OTC medication marketed as a nighttime medicine to treat the symptoms of cold, flu, and other respiratory conditions. It’s available as syrup and liquid caps.
Typically, NyQuil is combined with antihistamines, cough suppressants, and pain relief medications to treat cold and flu symptoms. It contains several active ingredients, including acetaminophen for pain relief, dextromethorphan to suppress cough, and doxylamine succinate, an antihistamine.
How Does NyQuil Work?
NyQuil products typically contain doxylamine, an antihistamine, and other ingredients like acetaminophen and dextromethorphan. Acetaminophen is used to relieve pain, and dextromethorphan suppresses cough to allow you to sleep.
Dayquil, the daytime version of the medication, is similar to NyQuil. It’s intended to be used during the day, so it contains acetaminophen and dextromethorphan without the antihistamines to avoid drowsiness.
How Long Does NyQuil Last?
Most people feel the effects of NyQuil within 30 minutes of ingestion. It provides relief for about 6 hours and is ideal for overnight relief from cold and flu symptoms.[2]
While NyQuil can last 4 to 6 hours, it can vary. People with slower metabolisms may need longer than 6 hours for the drug to be eliminated from the body, while people with faster metabolisms may eliminate it in a much shorter timeframe.
Recommended NyQuil Dosage
You should always follow the instructions on the product label or from your doctor, but the standard dosages of NyQuil include:[3]
- NyQuil syrup: 30 milliliters or 2 tablespoons every 6 hours as needed.
- NyQuil liquid caps: 2 capsules by mouth every 6 hours as necessary.
NyQuil is widely available over the counter and considered safe, but it’s important not to exceed the recommended dose or take multiple medications with similar ingredients. Doing so can lead to an overdose, so avoid taking more than 4 doses of NyQuil in 24 hours.
NyQuil Side Effects and Risks
The side effects of NyQuil are typically mild, but they may include:[4]
- Sedation
- Drowsiness
- Dry mouth or throat
- Lightheadedness
- Upset stomach
- Nausea
- Blurred vision
- Difficulty urinating
Avoid drinking alcohol while taking NyQuil, as this can increase the risk of liver damage and amplify the drowsiness you may experience. Like sedatives, NyQuil can impair your alertness and coordination, so you shouldn’t drive or do other activities that require focus while on the medication.
People with certain medical conditions shouldn’t take NyQuil as it can cause complications. These conditions include:[5]
- Liver or kidney disorders
- Asthma
- Diabetes
- High blood pressure
- Thyroid disorders
- Glaucoma
- Prostate enlargement
NyQuil can interact with certain medications, including sedatives, tranquilizers, and MAO inhibitors (antidepressants). Mixing NyQuil with antidepressants can cause serotonin syndrome, a life-threatening condition that leads to an accumulation of serotonin. The symptoms of serotonin syndrome can include increased body temperature, nausea and vomiting, fast heartbeat, and hallucinations, among others.[6]
Can You Overdose on NyQuil?
Yes, it’s possible to overdose on NyQuil. If you exceed the recommended dosage, you can experience confusion, difficulty breathing, and severe drowsiness. It’s important to seek medical attention as soon as possible if you suspect you’re experiencing a NyQuil overdose or someone else is.
Is NyQuil Addictive?
NyQuil isn’t addictive if you use it according to the instructions. Misusing NyQuil can cause dependence, which is when your body gets used to having a drug. If you stop abruptly, withdrawal can occur. Dependence is part of addiction, but it’s not an addiction on its own.
People may misuse NyQuil by taking too much to get the effects or using it to treat more serious respiratory conditions, such as asthma or chronic bronchitis. NyQuil is only intended to treat short-term symptoms of cold and flu, not chronic respiratory illnesses.
Some people take NyQuil for recreational purposes to experience its sedative effects, while others may take it as a sleep aid. NyQuil can cause drowsiness that helps with sleep, but it’s not a drug intended for insomnia and shouldn’t be used as a sleep aid.
If you take NyQuil to sleep, you can become dependent on it. When you stop, you may experience withdrawal symptoms like anxiety, cravings, restlessness, stomach pain, depression, and rebound insomnia.
Dextromethorphan Addiction
Another concern is taking large doses of NyQuil to get high. This can happen because dextromethorphan, one of NyQuil’s active ingredients, can cause mind-altering effects. In small doses, it works as a cough suppressant. It does affect the brain, which can lead to hallucinations or euphoria in high doses. Some may use NyQuil as a legal alternative to recreational drugs, particularly young people.
Misusing NyQuil for its dextromethorphan content can cause serious effects similar to those of PCP, a dangerous hallucinogen.[7] This drug impairs coordination and judgment. If it’s combined with other drugs, such as alcohol, acetaminophen, or antidepressants, it can cause serious liver damage, heart attacks, seizures, and possible death.
Treating NyQuil Addiction
While this may not seem like an addiction in the conventional sense, it’s no less uncomfortable. The symptoms of withdrawal can cause people to continue taking NyQuil to sleep and relieve the unpleasant symptoms, leading to a cycle of misuse and withdrawal.
If you’re experiencing NyQuil dependence or addiction, help is available. You may benefit from medical detox to manage the symptoms of withdrawal, address insomnia, and prevent relapse. Depending on your circumstances, you may want to enter an addiction treatment program to address the psychological and emotional aspects of addiction with therapy and counseling.
Seek Help for NyQuil Misuse and Addiction
NyQuil is a safe and widely available medication for cold and flu. But like any drug, misusing or abusing NyQuil can have risks, including the risk of serious side effects and complications like hallucinations and possible heart attack. If you’re struggling with NyQuil misuse or addiction, seek help with an addiction treatment program.
