Does NyQuil Make You Sleepy? Understanding the Effects and Safety

What is NyQuil?

Vicks NyQuil is an over-the-counter pain reliever, cough suppressant, and decongestant available in liquids and capsules that is designed to relieve flu and cold symptoms, like a runny nose, sneezing, or coughing, at night. 

Active Ingredients and Composition

The active ingredients in a standard 30 mL dose of NyQuil Liquid include:

• Acetaminophen (650 mg), which acts as a pain reliever and fever reducer
• Dextromethorphan HBr (30 mg), a cough suppressant
• Doxylamine succinate (12.5 mg), an antihistamine. 

It is important to note that NyQuil Severe also contains Phenylephrine HCl (10 mg) for congestion relief. Additionally, some preparations also contain alcohol and other inactive ingredients typically include citric acid, flavoring agents, and color additives.

Many individuals reach for NyQuil to deal with congestion, cough, body aches, or fever, as these symptoms make it difficult to get a good night’s sleep. Since NyQuil is marketed for use at night, it leads to some common questions: If I take NyQuil, will I become sleepy? What in NyQuil causes drowsiness, and will that drowsiness last into the next day?

These questions can apply to anyone taking any medication, especially if the person is sensitive to medication, taking care of a family or responsibilities, or dealing with mental health or substance use issues. 

At The Garden, a Cherry Hill, New Jersey outpatient substance abuse and alcohol rehabilitation center, we are aware that different medications can have different effects on different individuals.[1] The intention of this information is to give clear, deliberate details and enable an individual to make an informed choice when deciding whether to take NyQuil, as well as to recognize when additional care may be warranted. 

NyQuil Contains a Sedating Antihistamine

Because of the sedating antihistamine contained in NyQuil, many individuals feel drowsy after taking NyQuil. However, NyQuil is not indicated for use as a sleeping aid. The intent of NyQuil is to help reduce the symptoms resulting from a cold or flu that result in an inability to rest.

Why You Feel Drowsy

Some individuals may experience excessive sedation and others mild sleepiness, as individual responses to NyQuil will be influenced by several factors, such as metabolism and body chemistry. NyQuil produces a drowsy effect for two reasons:

1. CNS (the brain and spinal cord) Impact: First, it contains an ingredient that has a direct effect on the central nervous system, which includes the brain and spinal cord [2]. For many people, doxylamine succinate is the primary ingredient responsible for the sense of sleepiness.
2. Body Relaxation: Secondly, as NyQuil helps to relieve discomfort caused by coughing or body aches, naturally, the body will become more relaxed and ease falling asleep.

When taking NyQuil, drowsiness will typically begin about 30 minutes after you take it, although  thetime frame can differ, especially if taken with food.[1] Individual metabolism and overall reactivity to antihistamines affect how long NyQuil will help you stay asleep.

Duration of Effects

For the majority of users, the sleep-inducing effects of NyQuil last around 6 to 8 hours, which is the intended time frame for nighttime usage. The length of time someone remains drowsy from their NyQuil dose can depend on things like metabolism, age, body weight, liver function, and any sedating medications consumed at the same time.

Waking with a Foggy Feeling

Some people wake up with a foggy feeling or fuzzy thinking. This can occur due to the fact that doxylamine’s half-life (the time required for the concentration of the active substance in the body to decrease by half) is about 10-12 hours, meaning that it takes about that long for the average human body to remove 50% of the doxylamine from their system.[3]

When you take NyQuil in the late evening or are exceptionally sensitive to it, the residual sedation from that dose can carry over into the next morning and potentially hinder your ability to safely drive, work, or participate in your regular daily routine.[4]

Cautions and Warnings

Not Recommended as a Long-Term Sleep Aid

NyQuil is not an appropriate option for treating chronic insomnia or other long-term sleep problems. It is important to see a qualified healthcare provider if you are having sleep trouble longer than a week.

Don’t Perform Activities Requiring Physical Alertness

Because of the sedating nature of NyQuil, you should not engage in physical activities such as driving or operating machinery for a full night after taking it.[4] This is particularly true for those who have lingering sedating effects from a NyQuil dose.

Drug-Drug Interactions and Associated Risks

• Alcohol Risks: Do not take NyQuil with alcohol or other sedating drugs. Doing so significantly increases the risk of respiratory depression (suppressed breathing.) 
• Acetaminophen Monitoring: Monitor acetaminophen intake. Too much acetaminophen can result in liver damage, particularly among habitual alcohol drinkers.[6]
• Vulnerable Populations: Individuals who are pregnant, older adults, or those who have any form of liver disease or other medical conditions should discuss with their physician if using NyQuil is a safe option for them.[6]
• CNS Sensitivity: If there are two or more medications affecting an individual’s CNS, each should be taken with caution.

Support and Recovery at The Garden

While recovering from a substance use disorder, even over-the-counter medications may cause worry. The Garden encourages those who are in the process of recovery to engage in honest conversations with their treatment team regarding safe medication use, as well as helping them maintain their personal recovery goals through proper use of medication.

While NyQuil can assist with temporary relief from cold and flu symptoms, it should not be used without consideration for safety or as a tool to promote sleep long-term. If you or someone close to you has questions about using medication safely, sleep issues, or medication and substance use recovery interactions, we encourage you to provide gentle support. At The Garden, we take a holistic approach to honoring individuals and their families and helping to navigate through the continuum of care.

Frequently Asked Questions