Acetaminophen (paracetamol) is a well-known and widely used over the counter medicine with weaker anti-inflammatory effects and mild to moderate analgesic effect. It’s commonly used in treatment of fever and for the first line treatment of mild to moderate pains such as headache, toothache, menstrual pains, joint pain, post-operative pain and in general body aches. Onset of its analgesic action is 10 – 12 minutes after the oral administration and duration of action is about 6 hours. It’s administered as 4times per day or 6hrly dosing schedule.
Acetaminophen is well absorbed from stomach and small intestine; it’s metabolized by the liver and excreted via kidneys. It is safe in pregnancy, breast feeding and children. It’s available as tablets (adult and children), syrup, as rectal suppository and as intravenous preparation. It can be used combined with other analgesics for severe pains. Its lack of serious side effects at therapeutic doses makes it an ideal candidate for use in above situations as an over-the-counter medication.
Adverse effects of Acetaminophen-
• Minimal side effects with in therapeutic doses. Some gastric discomfort may occur in small number of individuals.
• Prolonged or excessive use can cause gastrointestinal irritation, kidney and liver damage. Liver toxicity is not common among general population but can be seen among chronic alcoholics and patients with already damaged livers due to some other disease.
Toxic dose of acetaminophen vary from patient to patient. Generally maximum daily dose is one gram (2x 500g tablets) per dose and four grams per day for adults. For children it is 15mg/kg of body weight per dose and 60mg/kg/per day. Higher doses will increase the risk of toxicity. In adults single dose above 10 grams (20 tablets) or >200mg/kg of body weight (even lower in certain situations) can lead to toxic features.
Risk factors for acetaminophen toxicity-
• Chronic alcoholism
• Fasting for prolonged periods
• Concomitant use of other drugs (antiepileptics like carbamazepine and phenobarbitone)
• High caffeine intake
• Malnourished people
• Other chronic illnesses
• Congenital liver diseases
Signs and symptoms of acetaminophen toxicity-
1st phase- within minutes to hours of overdose ( within first 24 hours)
• Metabolic acidosis
2nd phase – within 24 to 72 hours of overdose
• Abdominal pain in right upper quadrant
• Increased liver enzyme levels (SGOT & SGPT)
• Acute kidney failure – low urine output, swelling of body etc.
3rd phase- 3 to 5 days of overdose
• Coagulation defects – bleeding into skin, joints etc.
• Hepatic encephalopathy – altered sleep pattern, confusion, loss of consciousness
• Kidney failure
• Cerebral edema
• Multi organ failure
If the patient survives this third phase hepatic necrosis and liver, kidney functions returns to normal within few weeks.
Reasons for misuse-
• Accidental – using tablets too frequently (<6hrs), inappropriate large doses, presence of above risk factors.
• Intentional – suicidal attempts.
As this is a common medication, over dosage and toxicity is quite commonly seen among children as well as in adults. Though the definitive management is done in hospital; first aid care supporting vital functions until hospital admission can be of vital importance. First aid training should be focused on systematic approach on airway, breathing and circulation first in this kind of patients with any toxicity, leaving the management proper later on with definitive care.
First aid management of acetaminophen toxicity-
1. Stay calm and do not panic.
2. Talk to the patient and be with the patient.
3. If the patient is aggressive (in a suicidal attempt/ psychiatric patient) ensure the safety of yours, patient, and others before any intervention.
4. Call emergency services.
5. Double check the name of the drug and amount of tablets taken.
6. Note down the time of ingestion.
7. Avoid any kind of drug without medical advice.
8. If patient is vomiting turn to lateral side to prevent aspiration. If it’s soon after ingestion and patient conscious, give liberal amount of water to drink which facilitates vomiting, hence eliminating drug in the gut.
9. If the patient is unconscious check the airway; open and maintain the airway using chin lift, head tilt and jaw thrust maneuvers. Assess breathing and circulation and manage according to basic life support guidelines.
10. Observe until the emergency staff arrive.
1. Adherence to the correct dosing schedule.
2. For children, adjust dose according to the body weight.
3. Child resistant closure.
4. Keep away from children and psychiatric patients with suicidal risk.
5. Educate general population regarding toxicity and safe storage.