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Acetaminophen - Mechanism of Action, Indications, uses, Administration, Side Effects

Chemical Formula:

  • C8H9NO2

Mechanism of Action:

  • Acetaminophen, also known as paracetamol, is a widely used analgesic (pain reliever) and antipyretic (fever reducer).

  • While its exact mechanism of action is not fully understood, it is believed to involve modulation of the endogenous cannabinoid system and inhibition of prostaglandin synthesis in the central nervous system.

  • Acetaminophen mainly inhibits the synthesis of prostaglandins, which are lipid compounds involved in the transmission of pain signals and regulation of body temperature.

  • By reducing the production of prostaglandins, acetaminophen helps alleviate pain and reduce fever.

  • Unlike nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, acetaminophen has minimal anti-inflammatory effects, making it more suitable for individuals who cannot tolerate or are advised against using NSAIDs.

Indications and Uses:

Acetaminophen is commonly used for the treatment of:

  1. Mild to moderate pain: It is effective in relieving pain associated with headaches, toothaches, musculoskeletal conditions, menstrual cramps, and minor injuries.

  2. Fever: Acetaminophen is widely used to reduce fever in various conditions, including common colds, flu, and other febrile illnesses.

  • Additionally, acetaminophen may be used as part of combination medications for the management of more severe pain or in over-the-counter cough and cold remedies.

  • It is important to note that acetaminophen is not an anti-inflammatory drug and should not be used for the treatment of inflammatory conditions like arthritis.


  • Acetaminophen is available in various forms, including oral tablets, capsules, liquid suspension, and suppositories.

  • The appropriate form and dosage may depend on the age, weight, and specific condition being treated.

  • The dosage for adults is typically 325-1000 mg taken orally every 4-6 hours, not exceeding the recommended maximum daily dose.

  • It is important to follow the instructions provided on the product label or as directed by a healthcare professional.

  • In children, the dosage is determined based on their weight and age.

  • It is crucial to use appropriate pediatric formulations and follow the recommended dosage guidelines for children.

Side Effects:

  • Acetaminophen is generally well-tolerated when used at recommended doses.

  • However, exceeding the recommended dosage or long-term use can lead to liver toxicity.

Common side effects may include:

  1. Nausea or upset stomach

  2. Skin rash or allergic reactions

  3. Rarely, blood disorders in susceptible individuals

  • Severe liver damage can occur if acetaminophen is used in excessive doses or combined with alcohol or certain medications that affect liver function. It is important to adhere to recommended dosages and avoid exceeding the maximum daily dose.

  • Allergic reactions to acetaminophen are rare but can occur in some individuals. Symptoms may include skin rash, itching, swelling, or difficulty breathing. If any allergic reactions occur, medical attention should be sought immediately.

  • It is important to read product labels carefully, avoid exceeding the recommended dosage, and consult a healthcare professional if there are any concerns or if pain or fever persist or worsen.


  • Acetaminophen is a widely used analgesic and antipyretic medication.

  • Its mechanism of action involves the inhibition of prostaglandin synthesis in the central nervous system, resulting in pain relief and fever reduction.

  • Acetaminophen is commonly used to relieve mild to moderate pain and reduce fever.

  • It is generally safe when used as directed, but excessive dosage can lead to liver toxicity. It is important to follow recommended dos


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