How Long Does ZzzQuil Last? How Long Does it Take to Work?

You may have heard of the “Quil” range of products by Vicks. As a popular brand of cold and flu medication, users of NyQuil and DayQuil have survived many a sick season thanks to this effective medication. So when they introduced their new line, ZzzQuil, for those who have difficulty sleeping, we were all curious about its capabilities.

When trying new products that promise to help with an issue as frustrating as sleeplessness, you want to know if something like ZzzQuil is going to work for you. Admittedly, the Vicks website is surprisingly vague when it comes to answering how long it takes for ZzzQuil to kick in, but reports from those who have tried it say that it takes about 20-30 minutes for you to start feeling drowsy.

For most users, the ZzzQuil can stay in your system, making you feel tired for at least 6-8 hours after consumption. This is a rough estimate, however, because everyone’s body is different and how you react to medication may differ from others. (Source)

How ZzzQuill Works

The active ingredient (the chemical that is doing the work to make you drowsy) in ZzzQuil is diphenhydramine HCL (hydrochloride). If you have ever taken Benadryl for your allergies, you’ve had diphenhydramine HCL before. Typically used as an antihistamine for allergy sufferers, this ingredient is useful in most users for also causing drowsiness and relaxation.

In addition to being a histamine blocker, diphenhydramine has sedative properties, making it easier to fall asleep.

How Long ZzzQuil Lasts

All sleep medications recommend that you allow at least 6-7 hours of sleep; however some people may need up to eight hours before the effects wear off entirely. Failing to get enough sleep may result in a groggy morning or symptoms such as a headache, sometimes referred to as “the hangover.”

While ZzzQuil aims to help you fall and stay asleep, some people do still experience waking up throughout the night. If you happen to wake periodically, it does not mean that the medication is no longer in your system and shouldn’t be considered to have worn off.

Because it’s possible to stay awake for some time after taking a sleep aid or wake up throughout the night, you should plan to take ZzzQuil at least eight hours before you need to wake up.

Why Absorption Time Is Different

When talking to people who use sleep aids, you might notice that there are all different reports. Some people have immediate reactions, while for others, the absorption time can take longer (if they notice it at all). The same difference can be found when taking the medication from day-to-day. For this reason, you might not have the same reaction each time that you take ZzzQuil. Some things that affect how the sleep aid works include:

  • Your metabolism – Most medications will let you know if they should be taken with or without food. This is because of how your metabolism works with digesting and processing the medication. If you have recently eaten, it could take longer for the ZzzQuil to work as your stomach is busy breaking down the full course meal (and dessert) that you consumed beforehand. To ensure that the medication absorbs properly, try not to eat for about two hours before you’re ready to take it.
  • What you drink – Plenty of people use alcohol to help them fall asleep. While a few drinks might help you fall asleep, it won’t help you stay asleep. Additionally, you should never mix alcohol with sleep aids. The same goes for limiting your caffeine intake before bed.
  • How much you take – The recommended dosage for the ZzzQuil liquicaps is 50 mg (2 capsules). If you are used to taking sleep aids or have built up a resistance to them, taking only one or two capsules might not make a difference for you. On the other hand, if you don’t regularly take sleep medication, one pill may be enough.


If you are looking for an alternative product that produces similar results, I highly recommend using ZzzQuil Melatonin Sleep Aid (Link to Amazon) which provides a more natural sleep solution. I’ve been using them for a few months now, and have had a very positive experience. Being able to both get to sleep, and stay asleep consistently.


As a sleep aid, ZzzQuil can be a great short-term solution for sleeplessness. However, because the time it takes to absorb into the bloodstream is different for everyone, you may need to test it out to learn how your body reacts.

When trying to determine how long it stays in your system, you should plan to get a full night of sleep when taking ZzzQuil, meaning avoid taking it at midnight if you have to wake up at 6 a.m. for work. This will help ensure that the medication has time to run its course.

Sleeping with a sleep tracker will give you an idea of the effectiveness of ZzzQuil and help you decide if this sleep aid is right for you. As always, you should speak to your doctor when determining whether certain medications are appropriate for your individual situation. (Source)

Tiara Croft

Tiara is an avid sleeper and fully dedicated to her work and research. Most often this includes, but is not limited to, napping, testing how many hours in one night that she can sleep, trying new sleep methods and constantly changing sleep positions. Tiara's main focuses are on dreams and how we can achieve the best natural sleep possible. As a sufferer of insomnia and other sleep-related disturbances, Tiara loves to dig deep into the subconscious to ask all the questions that can help us better understand what happens when we sleep.

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