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What is Paracetamol? Uses, Side Effects, Dosage & More
- Analgesics
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💊 Drug Monograph · Analgesic / Antipyretic
What is Paracetamol? Uses, Side Effects, Dosage & More
A complete pharmacist-reviewed guide to Paracetamol (acetaminophen) — the world's most widely used pain reliever and fever reducer. Updated May 2025.
✅ Key Takeaways
- Paracetamol relieves mild-to-moderate pain and reduces fever — but does NOT reduce inflammation.
- Maximum adult dose: 4,000 mg/day (1,000 mg every 4–6 hours, max 4 doses/day).
- Safe for pregnant women, breastfeeding mothers, children, and elderly — at correct doses.
- Avoid in liver disease or heavy alcohol use — the liver processes paracetamol.
- Overdose is the leading cause of acute liver failure. Never exceed recommended dose.
- Can be safely combined with ibuprofen for stronger pain control.
Generic Name
Paracetamol
Also: Acetaminophen (US)
Drug Class
Analgesic
Antipyretic · Non-opioid
Adult Max Dose
4,000 mg/day
1 g every 4–6 hrs
Onset of Action
30–60 min
Duration: 4–6 hours
Pregnancy Safety
Generally Safe
Consult doctor first
Available OTC
Yes
No prescription needed
1 What is Paracetamol?
Paracetamol — known as acetaminophen in North America — is a widely used over-the-counter (OTC) medicine belonging to the class of analgesics (pain relievers) and antipyretics (fever reducers). It was first synthesised in 1877 and has been in clinical use since the 1950s, making it one of the longest-standing medicines in the world.
Unlike non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or aspirin, paracetamol does not significantly reduce inflammation. Its primary actions are on the central nervous system — it alters the perception of pain and acts on the hypothalamus (the brain's thermostat) to reduce fever.
Did You Know?
Paracetamol is the active ingredient in over 600 different medicines worldwide, including many cold and flu combinations, cough syrups, and prescription painkillers. Always check labels to avoid accidentally doubling your dose.
How Does Paracetamol Work?
The exact mechanism is not fully understood, but paracetamol is thought to work by inhibiting the synthesis of prostaglandins in the central nervous system — chemical messengers that sensitise nerve endings to pain and signal the brain to raise body temperature. Unlike NSAIDs, it does not significantly inhibit prostaglandins in peripheral tissues, which is why it lacks strong anti-inflammatory properties.
Recent research also suggests paracetamol may activate the body's own endocannabinoid system and interact with serotonin pathways to modulate pain perception at the spinal cord level.
2 Uses of Paracetamol
Paracetamol is indicated for the symptomatic relief of mild to moderate pain and for the management of fever. It is suitable across all age groups, from newborns to the elderly, when used at appropriate doses.
Headache
Tension & migraine
Toothache
Pre/post dental
Fever
All ages
Back Pain
Acute & chronic
Muscle Aches
Post-exercise
Period Pain
Dysmenorrhoea
Cold & Flu
Fever + aches
Post-Surgery
Mild pain relief
Paracetamol Does NOT Treat:
Rheumatoid arthritis, sprains, or other conditions requiring anti-inflammatory treatment. For inflammatory pain, ask your pharmacist about ibuprofen or naproxen. Paracetamol also does NOT relieve severe or chronic pain on its own — stronger medications are needed.
3 Dosage & How to Take
Always follow your pharmacist's or doctor's instructions. The doses below are standard guidelines for healthy individuals without liver or kidney conditions.
| Age / Patient Group | Single Dose | Frequency | Max/Day | Formulation |
|---|---|---|---|---|
| Adults (16+ yrs) | 500–1,000 mg | Every 4–6 hrs | 4,000 mg | Tablets, capsules, liquid |
| Elderly (65+) | 500–1,000 mg | Every 6–8 hrs | 3,000 mg | Tablets, liquid |
| Children 6–12 yrs | 250–500 mg | Every 4–6 hrs | 2,000 mg | Oral suspension, chewable |
| Children 1–5 yrs | 120–250 mg | Every 4–6 hrs | 1,000 mg | Oral suspension (120 mg/5 mL) |
| Infants 3–12 mths | 60–125 mg | Every 4–6 hrs | 500 mg | Drops / suppository |
| Liver Disease | ⚠️ Consult doctor — dose may need significant reduction or avoidance | |||
Weight-Based Dosing for Children
For children, the most accurate dosing is 15 mg per kg of body weight per dose, up to 60 mg/kg/day maximum. Example: a 20 kg child can receive up to 300 mg per dose. Always use the measuring syringe provided — kitchen spoons are inaccurate.
How to Take Paracetamol
- Can be taken with or without food — no stomach upset.
- Swallow tablets whole with a full glass of water.
- Do not crush extended-release (ER/SR) tablets — this destroys the controlled-release mechanism.
- Space doses at least 4 hours apart — never take a double dose to catch up.
- Stop taking and see a pharmacist if pain/fever has not improved after 3 days.
4 Side Effects
At recommended doses, paracetamol is one of the safest medicines available. Serious side effects at therapeutic doses are rare. The frequency ratings below are based on clinical literature.
Nausea / stomach discomfort
Common (1–10%)
Skin rash (allergic)
Uncommon (<1%)
Elevated liver enzymes
Uncommon (long-term)
Severe liver damage
Rare (overdose only)
Serious blood disorders
Very rare
Stop Immediately If You Experience:
Yellowing of skin or eyes (jaundice) · Severe abdominal pain · Dark urine · Unusual bruising or bleeding · Difficulty breathing or swelling of the face/throat (signs of allergic reaction). These may indicate liver damage or a severe allergic reaction — seek emergency care.
5 Drug Interactions
Paracetamol has relatively few drug interactions compared to NSAIDs, but some important ones exist — particularly those affecting the liver.
| Interacting Drug / Substance | Interaction | Action Required |
|---|---|---|
| Alcohol (chronic heavy use) | Greatly increases risk of liver toxicity | Avoid / Reduce dose |
| Warfarin (blood thinner) | Paracetamol may enhance anticoagulant effect | Monitor INR closely |
| Rifampicin / Isoniazid | Induces liver enzymes — increases toxic metabolite | Use lower dose / avoid |
| Carbamazepine / Phenytoin | Anticonvulsants reduce paracetamol effectiveness | Consult pharmacist |
| Cholestyramine | Reduces absorption of paracetamol | Take 1 hr before cholestyramine |
| Other paracetamol-containing products | Double-dosing risk — can cause overdose | Check all labels carefully |
6 Special Populations
🤰 Pregnancy
Paracetamol is traditionally considered the analgesic of choice during pregnancy. However, a growing body of research — including a 2021 consensus statement from international experts — recommends using paracetamol at the lowest effective dose for the shortest duration. Prolonged or high-dose use has been associated with a small increased risk of developmental effects in the baby. Always discuss with your doctor or pharmacist before use in pregnancy.
🤱 Breastfeeding
Paracetamol passes into breast milk in very small amounts. It is considered compatible with breastfeeding at standard therapeutic doses. It is the preferred analgesic/antipyretic for breastfeeding mothers.
👴 Elderly Patients
Older adults are more susceptible to side effects due to reduced liver and kidney function. A maximum of 3,000 mg/day is recommended for elderly patients. Paracetamol is preferred over NSAIDs in the elderly due to lower gastrointestinal and cardiovascular risk.
🫀 Liver Disease
Paracetamol is metabolised almost entirely by the liver. In patients with liver disease (hepatitis, cirrhosis), even therapeutic doses can cause liver damage. If paracetamol is needed, the maximum dose should not exceed 2,000 mg/day, and use should be supervised by a doctor.
Regular Alcohol Users
If you regularly drink 3 or more alcoholic drinks per day, consult your pharmacist or doctor before using paracetamol. Chronic alcohol use increases the production of a toxic paracetamol metabolite (NAPQI) that damages the liver.
7 Contraindications & Cautions
Absolute Contraindications
- Known hypersensitivity to paracetamol or any excipient in the formulation
- Severe hepatic impairment (active liver failure)
Use with Caution
- Chronic alcohol use (≥ 3 drinks/day)
- Mild-to-moderate liver disease (hepatitis, cirrhosis, Gilbert's syndrome)
- Severe renal impairment (doses should be spaced ≥8 hours apart)
- Malnutrition or very low body weight (depleted glutathione stores)
- G6PD deficiency (rare — associated with methaemoglobinaemia)
8 Paracetamol vs. Common Alternatives
How does paracetamol compare to other common OTC pain and fever medicines? Use this table to choose the right medicine for your situation.
| Feature | Paracetamol | Ibuprofen (NSAID) | Aspirin (NSAID) | Naproxen (NSAID) |
|---|---|---|---|---|
| Pain relief | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| Reduces fever | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| Anti-inflammatory | ❌ No | ✅ Yes | ✅ Yes | ✅ Yes |
| Safe in pregnancy | ✅ (low dose) | ⚠️ Avoid after 20 wks | ❌ Avoid | ⚠️ Avoid 3rd trimester |
| Safe for children | ✅ Yes | ✅ ≥3 months | ❌ Under 16 | ⚠️ ≥2 years only |
| Empty stomach OK | ✅ Yes | ⚠️ Take with food | ⚠️ Take with food | ⚠️ Take with food |
| Main organ risk | Liver | Kidneys / GI | GI / platelets | Kidneys / GI |
| Frequency (adults) | Every 4–6 hrs | Every 6–8 hrs | Every 4–6 hrs | Every 8–12 hrs |
9 Overdose & Storage
Paracetamol Overdose — Medical Emergency
Taking more than 4,000 mg/day (or less in at-risk groups) can cause potentially fatal liver failure. The initial symptoms may be mild — nausea, vomiting, stomach pain — but liver damage may not become apparent for 24–72 hours. Do NOT wait for symptoms to worsen. If you suspect an overdose, go to the nearest emergency room immediately or call your national poison control line.
Signs of Overdose
- Phase 1 (0–24 hrs): Nausea, vomiting, general malaise, pallor, sweating
- Phase 2 (24–72 hrs): Right upper abdominal pain, elevated liver enzymes (blood tests)
- Phase 3 (72–96 hrs): Peak liver toxicity — jaundice, confusion, bleeding disorders
- Phase 4 (4+ days): Either recovery or progression to acute liver failure
Treatment (Hospital)
The antidote is N-acetylcysteine (NAC), which replenishes the glutathione stores that protect the liver from the toxic metabolite NAPQI. It is most effective when given within 8 hours of overdose but can help up to 24 hours. This is why immediate hospital attendance is critical.
Storage Instructions
- Store below 25°C (77°F) in a dry place away from direct sunlight.
- Keep out of reach of children — child-proof containers recommended.
- Do not store in bathrooms — heat and humidity accelerate degradation.
- Do not use after the expiry date printed on the pack.
- Dispose of unused medicines safely at a pharmacy — do not flush down the toilet.
10 Frequently Asked Questions
Tap any question to expand the answer.
Paracetamol (acetaminophen) is used to relieve mild to moderate pain including headaches, toothache, back pain, period pain, and muscle aches. It is also used to reduce fever (high temperature) caused by colds, flu, and infections. Unlike NSAIDs, it does not reduce inflammation.
The maximum adult dose is 4,000 mg (4 g) per day — typically 1,000 mg (two 500 mg tablets) every 4–6 hours, not exceeding 4 doses in 24 hours. For people who drink alcohol regularly, have liver disease, or are underweight, the safe limit may be lower. Always follow your pharmacist or doctor's advice.
Yes, paracetamol can be taken with or without food. Unlike ibuprofen or aspirin, it does not irritate the stomach lining, making it a safer choice for people with sensitive stomachs or ulcers.
Paracetamol is generally considered the pain reliever of choice during pregnancy when used at the lowest effective dose for the shortest time. However, emerging research suggests prolonged or high-dose use may carry risks. Always consult your doctor or pharmacist before taking any medicine during pregnancy.
Taking too much paracetamol can cause serious liver damage, which may not be immediately obvious. Symptoms of overdose include nausea, vomiting, stomach pain, and yellowing of the skin (jaundice) appearing 1–3 days after. Paracetamol overdose is a medical emergency — seek immediate treatment at an emergency room or call your national poison control line.
Paracetamol works mainly in the brain to block pain signals and reduce fever, but has no significant anti-inflammatory effect. Ibuprofen reduces pain, fever, AND inflammation, making it better for inflammatory conditions like arthritis or sports injuries. However, ibuprofen should not be taken on an empty stomach and is avoided in kidney disease, while paracetamol should be used cautiously in liver disease.
Yes, paracetamol is one of the most commonly used medicines for children's pain and fever. The dose is calculated by the child's weight — typically 15 mg per kg every 4–6 hours, up to a maximum of 4 doses in 24 hours. Use the children's formulation (oral suspension or suppositories) and always use the measuring syringe provided.
No. Paracetamol (acetaminophen) and aspirin (acetylsalicylic acid) are completely different medicines with different chemical structures and mechanisms. They can sometimes be combined in the same product (e.g. some cold and flu tablets), so always read the ingredient label before taking multiple medicines together.
Yes, paracetamol and ibuprofen can generally be taken together because they work through different mechanisms and do not interact significantly. Some doctors recommend alternating doses for better pain control. However, combining them increases the total medication burden — do not exceed the maximum dose of either medicine, and consult your pharmacist first if you have kidney or liver conditions.
Paracetamol typically starts working within 30–60 minutes after an oral dose. Peak blood levels are reached at 30–90 minutes. The pain-relieving and fever-reducing effects last approximately 4–6 hours. Modified-release formulations may take longer to start but last up to 8 hours.
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Medical & Affiliate Disclaimer This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement or medication. Some links in this post are affiliate links - if you purchase through them, Enavec Pharmacy may earn a small commission at no extra cost to you.
