Analgesic / antipyretic
Paracetamol (acetaminophen)
Central inhibition of prostaglandin synthesis with contributions from serotonergic and endocannabinoid pathways; negligible peripheral anti-inflammatory effect.
Brands
Calpol · Crocin · Tylenol · Perfalgan
Adult dosing
Maximum 4 g/day in a healthy adult over 50 kg| Indication | Dose | Route | Frequency |
|---|---|---|---|
| Pain or fever, over 50 kg | 1 gMax 4 g/day | Oral, IV or rectal | Every 4-6 hours |
| Body weight under 50 kg or frailty | 15 mg/kg (usually 500 mg)Max 60 mg/kg/day, capped at 3 g/day | Oral or IV | Every 6 hours |
Weight-based: 15 mg/kg per dose is the universal paediatric and low-weight adult rule.
Paediatric dosing
Always confirm the weight and the local paediatric formulary| Indication | Dose | Route | Frequency |
|---|---|---|---|
| Children and infants over 3 months | 15 mg/kg/doseMax 60 mg/kg/day, maximum 4 doses in 24 hours | Oral | Every 4-6 hours |
| Neonate (term) | 10-15 mg/kg/doseMax 60 mg/kg/day | Oral | Every 6-8 hours |
| Intravenous, children 10-50 kg | 15 mg/kg/doseMax 60 mg/kg/day | IV | Every 6 hours |
Renal adjustment
Move the slider to the patient's eGFRNo adjustment
- eGFR > 30No adjustment
- eGFR 10-30Extend to every 6 hours
- eGFR < 10Every 8 hours
Hepatic adjustment
- Chronic liver disease without failureMaximum 2-3 g/day
- Decompensated failure, malnutrition or active alcohol misuseMaximum 2 g/day or avoid
Practical notes
The things that go wrong at the bedside- The commonest overdose route is duplicate combination products — check every co-prescription.
- Preferred antipyretic in suspected dengue because NSAIDs add bleeding risk.
DrZep structured dosing table (demo dataset, formulary-aligned) · DrZep. Confirm every dose against your local formulary and the patient's weight, renal function and comorbidities.
Indications
- Fever
- Mild to moderate pain
- Component of multimodal analgesia
- Antipyretic of choice in dengue and pregnancy
Dosing summary
- Adult oral
- 500 mg-1 g every 4-6 h; maximum 4 g/24 h
- Adult under 50 kg
- 15 mg/kg per dose, maximum 60 mg/kg/day
- Children
- 15 mg/kg every 4-6 h, maximum 60 mg/kg/day
- Intravenous
- 1 g every 6 h in adults over 50 kg
Organ adjustment
Renal
- eGFR 10-50
- Extend interval to every 6 h
- eGFR < 10
- Every 8 h
Hepatic
- Chronic liver disease / malnutrition / alcohol excess
- Maximum 2-3 g/day
- Acute hepatic failure
- Avoid
Monitoring
- 1Total daily dose across all products
- 2Liver function in prolonged use, low body weight or liver disease
Contraindications & cautions
Do not use / use with care
- Known hypersensitivity
- Severe hepatocellular insufficiency
Pregnancy & lactation
- Pregnancy
- Analgesic and antipyretic of choice; use the lowest effective dose for the shortest time.
- Lactation
- Compatible and preferred.
Interactions
- WarfarinRegular high-dose use may raise INRmoderate
- Enzyme inducers (carbamazepine, rifampicin, isoniazid)Increased hepatotoxic metabolite formationmoderate
- Chronic alcoholReduced glutathione and increased hepatotoxicity riskmajor
- Other paracetamol-containing combination productsInadvertent overdose — a common cause of hepatotoxicitymajor
Adverse effects
Common
- Well tolerated at therapeutic doses
- Rare rash
Serious
- Hepatotoxicity in overdose
- Rare thrombocytopenia and agranulocytosis
- Anaphylaxis (rare)
Toxicity & overdose
Recognise and treat
- Overdose: initially asymptomatic, then vomiting and right upper quadrant pain at 24-48 h, hepatic failure at 72-96 h
- Plot the 4-hour or later level on the treatment nomogram; give N-acetylcysteine without waiting in staggered or unknown-timing overdose
- Use King's College criteria to guide transplant referral
Alternatives
- NSAIDs where not contraindicated
- Topical analgesics
- Opioids for severe pain within a stewardship framework
Linked diseases & guidelines
Demo monograph for educational use. Always confirm dose, route and interactions against your national formulary and the product label before prescribing.
Demo content. Educational decision support only. Verify every dose, citation and recommendation against your national formulary and the primary source before clinical use.