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Acetaminophen and its uses and side effects

Currently, acetaminophen is one of the most widely used drugs in the world and is used as an analgesic and antipyretic drug in all parts of the world. This medicine is very effective in reducing various pains and fevers, including common pains, coughs, headaches, etc. Acetaminophen is commonly found in everyone’s home, but with so much popularity and widespread use, you may have questions about its function, side effects, and precautions. This article is prepared with the aim of improving your awareness of the drug acetaminophen and its related concepts.

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Pharmaceutical forms of acetaminophen

Acetaminophen is a very old drug and was produced for the first time in 1877. For this reason, it is almost completely known to all doctors and its side effects have been fully investigated.

Pharmaceutical forms include 325 mg and 500 mg tablets, 325 mg and 500 mg capsules, 650 mg prolonged release caplets, 80 mg and 160 mg disintegrating oral tablets, 80 mg chewable tablets, oral solution or suspension. 160 mg / 5 ml, oral liquid is 160 mg / 5 ml and 500 mg / 5 ml, oral syrup is 160 mg / 5 ml.

Acetaminophen uses

This medicine is used to treat mild to moderate pain (from headache, menstrual period, toothache, back pain, arthritis or pain, cold and flu pain) and reduce fever. This drug is also used for mild to moderate pains of various origins such as headache, toothache, migraine, nerve pain, etc.

Uses of acetaminophen in adults

  1. pain and fever
  2. severe headache
  3. Period pain
  4. a cold
  5. Severe toothache and teething of the child
  6. Reducing the symptoms of sinusitis
  7. Treatment of back pain
  8. Arthritis disease

Pharmacological effects and mechanism of action of acetaminophen drug

The mechanism of action of this drug acts on the hypothalamus to produce fever. It may also work peripherally to block the generation of pain impulses and inhibit prostaglandin synthesis in the CNS. peak plasma time 10-60 minutes (immediate PO release); 60-120 minutes (PO extended release); 6 hours (PO 500 mg, regular tablet); 8 hours (PO 650 mg, extended-release tablet).

Metabolism takes place through the liver (microsomal enzyme systems) and conjugation (glucuronic or sulfuric acid) and finally it is excreted through urine (mainly in the form of acetaminophen glucuronide with acetaminophen sulfate and mercaptate).

Dosage of acetaminophen

Acetaminophen (acetaminophen) is produced in pharmaceutical forms and by different companies in the country and abroad. Carefully read the dosage instructions for each medication, as the amount of acetaminophen may vary from company to company. If you are giving acetaminophen to a child, make sure you are using a product that is designed for children. Use your child’s weight to find the right dose on the medicine package.

The amount of acetaminophen used in pain and fever

  1. Regular-strength immediate-release acetaminophen, 325-650 mg every 4 hours, not to exceed a total of 3250 mg per day. Also, under the supervision of a healthcare professional, a daily dose of up to 4 grams per day may be used.
  2. Extra strength, 1,000 mg every 6 to 8 hours, not to exceed 3,000 mg per day.
  3. Extended release, 2 capsules (1300 mg) every 8 hours not to exceed 3.9 g/day.
  4. When calculating the maximum daily dose, consider all sources of acetaminophen, including OTC and routes of administration, so as not to exceed the maximum recommended daily dose.
  5. It should not be used in people with liver disorders as much as possible, in case of use, you should be careful and limit the treatment to short-term use in doses of more than 2 grams per day.

Time to take acetaminophen tablets

Measure the liquid medicine with a spoon, dropper, or syringe to make sure you are using the correct dose. Also, the tablets that dissolve at a high speed, it is better to first chew the tablet and dissolve it on the tongue and then swallow it with or without water. For chewable tablets, chew thoroughly before swallowing and avoid prolonged-release tablets.

Doing so can release all the medicine at once and increase the risk of side effects. Do not take acetaminophen for pain for more than 10 days (5 days in children) unless prescribed by your doctor.


Before taking different pharmaceutical forms of acetaminophen, if you are allergic to this drug or its other ingredients, avoid using it. This product may contain inactive ingredients that can cause allergic reactions or sensitivities. People with medical records such as liver disease, regular use or abuse of alcohol, kidney disorder, heart problems, etc. should use with caution. Use caution in patients with diabetes, phenylketonuria (PKU), or any other condition that requires you to limit or avoid these substances in your diet.

  1. Hypersensitivity and anaphylactic reactions have been reported. In case of signs of allergic reactions or hypersensitivity, discontinue use immediately.
  2. Acetaminophen is available in many dosage forms, read the drug information carefully to avoid overdose.
  3. Use caution in patients with liver failure or active liver disease.
  4. The risk of hepatotoxicity is greater in patients taking chronically high doses or using more than one acetaminophen-containing product.
  5. Use caution in patients with severe renal failure. Consider adjusting the dose based on the patient’s physical health and age.
  6. Use with caution in patients with G6PD deficiency, also use caution in patients with chronic malnutrition.
  7. Risk of rare but serious skin reactions that can be fatal. These reactions include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Symptoms may include skin redness, blisters, and rashes.
  8. Limit the dose of acetaminophen from all sources and routes to less than 4 g/day in adults.

Caution in using acetaminophen

Taking too much acetaminophen can cause serious (possibly fatal) liver disease. Adults should not take more than 4,000 milligrams (4 grams) of acetaminophen per day. People with liver problems and children should take less acetaminophen. Ask your doctor or pharmacist how much of this medicine is safe to take. It is found in many over-the-counter and prescription medications (such as pain and fever relievers or cough and cold products).

Check the label on all your medications to see if they contain acetaminophen, and ask your pharmacist if you’re not sure. Symptoms of overdose of this drug include the following:

  1. nausea and vomiting
  2. loss of appetite
  3. Sweating
  4. Stomach or abdominal pain
  5. fatigue
  6. Yellow eyes and skin
  7. dark urine

Contraindications to the use of acetaminophen

  1. Hypersensitivity
  2. Severe active liver disease

Side effects of acetaminophen

Acetaminophen drug does not have side effects in most patients and side effects occur only in case of excessive and continuous use. A very serious allergic reaction to this drug is rare. However, if you notice signs of a serious allergic reaction such as skin rash, itching or swelling (especially in the face, tongue and throat), severe dizziness, difficulty breathing, etc., see a doctor. Pregnant women and lactating mothers should avoid taking painkillers without a prescription. Excessive use of acetaminophen without a prescription will have negative effects on the fetus and the baby.

  1. angioedema
  2. wandering
  3. dizziness
  4. Itchy maculopapular rash
  5. Hepatotoxicity
  6. liver failure
  7. Nephrotoxicity
  8. Hyperammonemia
  9. Stevens-Johnson syndrome
  10. Toxic epidermal necrolysis
  11. urticaria
  12. digestive bleeding

Acetaminophen tablets for fever

Drug interaction of acetaminophen

Patients, before going to the doctor, prepare a list of the chemical and herbal medicines you use so that the doctor can prescribe a prescription based on it. Drug interactions may change how your medications work or increase your risk of serious side effects. Ketoconazole and Levoctoconazole are among the drugs that cause drug interactions with acetaminophen.

This medicine may interfere with some tests and possibly cause false test results. Make sure that the laboratory personnel and all your doctors are aware of the use of this medicine.

  1. Category X interactions (avoidance): No significant interaction has been observed.
  2. Reducing the effects of acetaminophen by drugs: barbiturates, carbamazepine, fosphenytoin-phenytoin, isoniazid, lorlatinib
  3. Enhancement of drug effects by acetaminophen: busulfan, dasatinib, imatinib, local anesthetics, mipomersen, phenylephrine (systemic), prilocaine, sodium nitrite, sorafenib, vitamin K antagonists
  4. Increased effects of acetaminophen by drugs: nitric oxide, probenecid, sorafenib, dapsone (topical), dasatinib, flucloxacillin, isoniazid

Taking acetaminophen tablets during pregnancy and breastfeeding

Acetaminophen crosses the placenta and can be detected in the umbilical cord blood, baby serum and urine immediately after delivery. An increased risk of teratogenic effects after maternal use of the drug during pregnancy has not been reported. Also, the use of normal doses during pregnancy that is not associated with an increased risk of miscarriage or stillbirth. However, increased fetal death or spontaneous abortion may occur with maternal overdose if treatment is delayed. Wheezing and asthma in early childhood are related to the frequent use of this drug by the mother during pregnancy.

Storage conditions for acetaminophen

Acetaminophen should be kept out of the reach of children and animals. Also, this medicine should be stored at room temperature and away from light and moisture. If this medicine is no longer needed, dispose of it properly.

A final word on acetaminophen

In this article, we reviewed the drug acetaminophen from the Green Positive Online Pharmacy magazine. Finally, acetaminophen seems to be a safe and low-risk option as one of the basic and effective drugs in the treatment of common pains and fevers. With a long history of use and educational research surrounding it, this drug allows people to confidently use it to relieve pain and fever. However, we should not forget that the use of acetaminophen may also be associated with issues such as high consumption and drug interactions that can lead to side problems.

Site source: Medscape

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