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How Long Does Nyquil Last

Nidhi Nangia
By Nidhi Nangia. Updated: June 17, 2020
How Long Does Nyquil Last
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When you have a sore throat or you have an allergy attack, Nyquil proves to be the most effective over-the-counter remedy to fix it. Although it is effective in dealing with such conditions, it doesn't come without side effects. The dreaded Nyquil hangover is one of them, Like drinking alcohol or taking any medication which might alter your body chemistry, there are often after effects which can make you question your impulse to take them in the first place. With this guide at oneHOWTO, you will get complete information about the effects of Nyquil, and how long does Nyquil last.

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  1. What is Nyquil?
  2. When to take Nyquil?
  3. Side effects of Nyquil
  4. Nyquil variations
  5. How much time Nyquil takes to start working
  6. How long do Nyquil effects last?
  7. Factors that influence how long Nyquil will stay in your system

What is Nyquil?

Nyquil consists of two medications, dextromethorphan and chlorpheniramine. One is an antihistamine and the other is a cough suppressant. It is a popular and effective over-the-counter medicine used to treating symptoms of influenza, allergies and common cold. The word ‘Nyquil’ is a combination of ‘night’ and tranquil’, which clearly indicates that it should be used during night time and it works by maximizing tranquility and helping to induce sleep.

It allows you to sleep without disruption and you do not wake up frequently due to disturbances. It also contains doxylamine succinate which is found to be efficient in maintaining sleep if you have certain illnesses.

How Long Does Nyquil Last - What is Nyquil?

When to take Nyquil?

Nyquil is an OTC (over the counter) medication which is used for treating symptoms of flu and common cold, such as throat soreness, sneezing, minor pains and aches, headache, runny nose, cough and fever. This means you don't need a prescription from a doctor to purchase it. The best time to take Nyquil is just before going to sleep, because it contains sedatives that help you get the sleep and rest that you need to fight against the symptoms. If you take it at other times when you aren't going to sleep it can affect your behavior and ability to stay awake. Don't drive or operate heavy machinery if you have taken Nyquil and don't know the effect it can have on your body.

Side effects of Nyquil

Although Nyquil is available over the counter without any prescription, and is generally considered to be a safe product to use, it does come with certain side effects. Some of them are:

  • Dizziness
  • Extreme drowsiness
  • Nervousness and anxiety
  • Excitability
  • Weakness and fatigue
  • Loss of appetite
  • Diarrhea or constipation
  • Vomiting and stomach upset
  • Hangover

These side effects can be potentially dangerous while driving, operating machines or doing any other such activities that require attention and alertness. That is why, it is always recommended to be taken during night time. If you need to take it during daytime, make sure that you stay at home and take complete rest after taking your Nyquil dose.

Nyquil variations

There are a number of Nyquil variations available out there:

  • Nyquil: The standard product, it contains acetaminophen which relieves pain and reduces fever, dextromethorphan that suppresses cough and doxylamine succinate to induce sleep.
  • Nyquil Severe: This stronger version of Nyquil contains all the ingredients of the main drug, but with a dose of phenylephrine as well. It is an effective nasal decongestant that relieves your cold symptoms during night.
  • Nyquil Cough: It does not contain acetaminophen, but has doxylamine succinate and dextromethorphan to relieve your coughing.
  • DayQuil: This variation is suitable to be taken during the day. It contains acetaminophen and phenylephrine, but no antihistamines and low dosage of dextromethorphan. Due to its composition, it can keep you awake without dozing you off.
  • ZzzQuil: It contains diphenhydramine which is effective in dealing with several symptoms of common cold and allergies, such as itching, runny nose, sneezing and hives.
  • QlearQuil: There are four different variations of QlearQuil, all of which are targeted at relieving symptoms of allergies. Its variations are Nighttime Allergy Relief, All Day & All Night 24 Hour Allergy Relief, Nighttime Sinus & Congestion Relief and Daytime Sinus & Congestion Relief.

How much time Nyquil takes to start working

Nyquil starts working almost immediately. If you take liquid Nyquil, you will immediately experience a warm sensation running down your throat. It feels most like you have just taken a shot of something. Nyquil pills take around 8-10 minutes to start showing effects.

Your entire body will feel warm and your aches will start fading away. Soon, you will feel your eyelids drooping and feel the dire need to sleep. At this time, you should lie in your bed, slide under your blanket and allow the drug to make you sleep. When you wake up, you will have heavy eyes and difficulty focusing. This hangover will likely keep you groggy for at least the start of the day, after which you should be ready to go back to work.

How Long Does Nyquil Last - How much time Nyquil takes to start working

How long do Nyquil effects last?

If you want to know how long Nyquil effects will last, you need to learn about the different ingredients present in the medication. Although all formulations of Nyquil contain doxylamine succinate to induce sleep, you need to know the half lives of other ingredients to determine how long they will stay in your system:

  • Doxylamine succinate: This ingredient is present in all the variations of Nyquil, and 50% of it stays for around 10 hours in the body of a healthy adult. This means that 50% of it gets eliminated from your systemic circulation after 10 hours and further half lives are eliminated in approximately 2.25 days.
  • Acetaminophen: All Nyquil variations, except Nyquil Cough, contain this ingredient. 50% of this drug is eliminated from your system within 1-4 hours, but usually it takes 2-3 hours in a healthy adult. So, we can estimate that all of it is eliminated from your boy only after 22 hours of consumption.
  • Dextromethorphan: Also known as DXM, 50% of this drug is eliminated only after 3-6 hours, and all of it is removed only after 11-33 hours.
  • Phenylephrine: Nyquil variations that are formulated to remove congestion from nasal passages contain this ingredient. Having a shorter half life, 50% of it is eliminated within 2-3 hours. All of the drug is removed between 6 to 18 hours after ingestion.
  • Pseudoephedrine: This is another ingredient used for decongesting nasal passages. 50% of it is usually removed from your body after 2 to 21 hours, depending on your age and urine pH. On an average, it happens after around 6 hours in a healthy adult. Most people will remove all of the drug from their system in around 33 hours after consumption

Now that we know the half life of all of the drugs present in Nyquil, we can identify that doxylamine succinate stays in your system for the longest period of time. It takes around 2.25 days to completely eliminate from your system. Since all Nyquil variations contain this drug, they can keep you drowsy for several 2-3 days after ingestion.

Factors that influence how long Nyquil will stay in your system

There are several factors that affect the duration for which Nyquil will stay in your system:

  • Age: Age of the user can significantly alter the pharmacokinetics of different ingredients. For instance, elderly patients have poor hepatic and rental function, due to which they may experience the side effects for longer.
  • Body mass: Doxylamine succinate present in Nyquil is soluble in fat. So, if you have high body fat percentage, more of the drug will be accumulated in your system and you will experience its effects for longer.
  • Glutathione levels: Individuals with depleted or low levels of glutathione will accumulate more of the drug and it will take longer for them to eliminate it completely.
  • Metabolism: People with high metabolic rate will burn and utilize the drug faster than those with slow metabolism.
  • Dosage: The bigger dose you take, the longer it will take to eliminate from your systemic circulation.
  • Frequency of administration: The frequency of taking Nyquil and for how long you have taken it will also affect how long it will last in your system. This is because your body builds up a tolerance, similar to how if you take most things (such as alcohol), you can develop a tolerance.
  • Co-administration of other drugs: Other drugs you take along with Nyquil also affects the duration for which it will stay in your system.

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to How Long Does Nyquil Last, we recommend you visit our Drugs & supplements category.

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