How Long Does Acetaminophen Stay In Your System?

June 16, 2017

Jelly Bell

How Long Does Acetaminophen Stay In Your System?

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Acetaminophen is used in pain relief and anti-fever. Acetaminophen is one of the main components in many kinds of pain killers. They are prescribed in acute pain (headache, toothache, backache, pain in muscle…) and from mild to severe fever.

However, still remains the aspects that we have to be clear. We do not know the important knowledge about acetaminophen that necessary for us. We need to understand how acetaminophen act on your body, the acetaminophen dosage, the effect, how much acetaminophen can you take, how long does acetaminophen take to work, how long does acetaminophen stay in your system, how much acetaminophen is too much, the side effects, etc…

Do you know the use of acetaminophen?

These information are not replaced the medical advice of physicians so that remember to consult the doctors and pharmacists before using acetaminophen. The use of too much acetaminophen may cause the toxic on liver, kidneys or even death [1].

Regular dose for adults with fever or pain:

For oral preparations, you use the following:

  • Quick release formulations: You take 325 mg to 1 g every 4 to 6 hours. Single maximum dose is 1 g and maximum 4 g in 24 hours.
  • Extended release drug form: You take 1300 mg orally every 8 hours. The maximum dose is 3900 mg every 24 hours.
  • For rectal progesterone preparations: you take 650 mg oral every 4 to 6 hours, up to 3900 mg every 24 hours.

Regular dose for children with fever or pain:

Children under 12 years of age are given weight-based dose; you give them 10 to 15 mg/kg per dose, every 4 to 6 hours, up to 5 doses in 24 hours.

You can adjust the dose for children as follows:

NumberAgeWeight (kg)Mg/doseOral solution (mg/ml)Intake (ml)
10 – 3 months2.7 – 5.340160/51.25
24 – 11 months5.4 – 8.180160/52.5
312 – 23 months8.2 – 10.8120160/53.75
424 – 36 months10.9 – 16.3160160/55
54 – 5 years old16.4 – 21.7160160/57.5
66 – 12 years old325160/5


  • Children 12 to 23 months: For chewable tablets (80 mg tablets), give your child 1.5 tablets;
  • Children 2-3 years old. For chewable tablets, give your child 2 tablets of 80 mg or 1 tablet of 160 mg;
  • Children 4-5 years old: Three 80 mg chewable tablets or 1.5 chewable tablets of 160 mg;
  • Children 6-12 years of age, you give your child 325 mg every 4-6 hours, do not exceed 1.625 g per day for 5 days unless instructed by a doctor;
  • Children 12 and older may take the following drugs:

For regular strength, give your child 650 mg every 4-6 hours, not to exceed 3.25 g during 24 hours, under the supervision of a health professional, the dose may reach 4 g per day;

For extra strength, give your child 1000 mg every 6 hours, do not exceed 3 g in 24 hours, under the supervision of a health professional, the dose may reach 4 g per day;

For prolonged release, give the infant 1.3 g every 8 hours, not to exceed 3.9 g in 24 hours [2].

How long does acetaminophen stay in your system?

There are several research which had been done to demonstrate the highest level of acetaminophen in our blood and the half duration of acetaminophen.

Following the experts, the acetaminophen level reaches a peak in human plasma is from 0.5 to 2 hours after you take the medication by oral. The half-life of acetaminophen is from 2 to 4 hours. This means acetaminophen has effects on our body after 0.5 hours after we take it, remains and peaks in next 1.5 hours and decline the level in the next 2 hours. So that it is effective in the first 4 hours. That why we have to take acetaminophen in each 4 to 6 hours to get the best treatment result.

acetaminophen stay in your system

What’s happened when overdose of acetaminophen?

The using of acetaminophen high which over the prescription dosage for each individual may cause many problems and death is the latest consequence. Because of lacking knowledge about acetaminophen, we do not know how much acetaminophen is too much and the signs of overdose acetaminophen.

The first signs of overdose of acetaminophen include loss of appetite, nausea, vomiting, abdominal pain, sweating, confusion or weakness. Symptoms may then include pain in the upper abdomen, dark urine, jaundice, or whites of the eyes [2].

Acetaminophen for pregnant and lactation women

There is lack of study that determined the risk of this medication during pregnancy or lactation. Before taking medicine, you need to consult your doctor to outweigh the benefits and risks.

What is acetaminophen side effect?

You should call for emergency if you have one in any of the following signs that is a reaction to allergy of acetaminophen such as rash, difficulty breathing, and swelling of the face, lips, tongue, or throat. Stop using acetaminophen immediately and call for your doctor right away when you have one of following side effects like nausea, abdominal pain, itching, anorexia, dark urine, and clay color, jaundice [3].

Which forms of acetaminophen?

There are many kinds of acetaminophen forms which suitable for adults, children or any ages such as: liquid form, tablets (dissolving tablets, chewable tablets, prolonged release tablets, effervescent tablets), capsules, tablets, powdered or reconstituted powder, syrup, suspension or elixir.

Acetaminophen may not be closed to some of you but you might know Tylenol, Panadol, Tempra, Anacin-3 and Datril. Panadol is wide using in more than 80 countries in the world in Asia, Europe, Africa and Australia. In the north of America and other parts of the world, Tylenol is seemed like the most popular product of acetaminophen and paracetamol.


One of the typical types of acetaminophen that used is Tylenol acetaminophen. Tylenol is a decongestant that is commonly used in many countries. In fact, the abuse of Tylenol containing acetaminophen (a multifunctional molecule) can affect the liver if used overdose or abuse.

Tylenol 500mg is often prescribed for adults. We should take Tylenol after meal. However, there a number of case which have Tylenol toxic or even death because of Tylenol. These consequences may cause that you do not know how long does Tylenol last, how long does Tylenol stay in your system and how often can you take Tylenol [4].

In fact, adults and children over 12 years old should take 2 tablets every 6 hours Tylenol is a kind of acetaminophen so that the life-time of Tylenol is from 4 to 6 hours which mentioned above. But remember that do not use in children under 12 years old. This is dangerous if you do not know.

Remember that do not take more than 6 tablets in 24 hours, unless directed by a doctor. Because of the life-time (from 4 to 6 hours) and the peak in human serum, the maximum tablet is 6 for each 4 hours. Discontinue use when the pain is worse and last more than 10 days. Discontinue use when the fever gets worse and lasts more than 3 days.

Questions and Answers

1. Is acetaminophen used for infants and children?

Yes. We can use as some kind of products such as children Tylenol. Children and infants may use in syrup, rectal preparation, powdered or reconstituted powder. However Tylenol 500mg is not used for children under 12 years old.

2. How long can I take acetaminophen?

Depending on age, weight and the severity, acetaminophen can take during 4 to 6 hours. Do not take more than 6 tablets of acetaminophen in 24 hours.

3. If I have pregnancy, should I use acetaminophen as a kind of pain killer?

No, you should not take acetaminophen by yourself. You should consult by your doctor before using acetaminophen or any kinds of medication.

4. I wonder know that Is acetaminophen is the best pain killer?

There are several kinds of pain killer nowadays. It depends on your situation and condition that doctor gives you the prescription. However, NSAIDs are typical first choice for pain killers. Acetaminophen is a common NSAID.

5. What should I do if my children are overdosed of acetaminophen?

When your children have one of the signs of overdose acetaminophen, you should calm down and call for emergency medical help immediately.

6. Can I use Panadol or other types of acetaminophen instead of Tylenol?

Yes, of course. Panadol, Tylenol or any other types, all have the main component is acetaminophen. They are different in the names and sub-components (excipients).

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