Paracetamol, also known as acetaminophen, is one of the most common pain relievers available over the counter. It is effective for treating mild to moderate pain from headaches, muscle aches, backaches, toothaches, colds and fevers. Paracetamol is also used to reduce fever.
The recommended maximum daily dose for paracetamol is 4000mg per day for adults and teenagers over 16 years old. This equates to 4 standard 500mg tablets taken over the course of the day. For children under 16, the daily dose depends on their age and weight – your pharmacist can advise you on the appropriate dose.
Quick answers
- The maximum daily dose of paracetamol for adults is 4000mg.
- This equates to 4 tablets containing 1000mg paracetamol.
- Doses should be spaced out evenly over the day every 4-6 hours.
- Taking more than the recommended dose can cause serious liver damage.
- Liver damage can occur if more than 4000mg is taken over 24 hours.
Why should you not exceed the maximum dose?
Exceeding the recommended maximum daily dose of 4000mg paracetamol can cause liver damage. Paracetamol is metabolised by the liver, so taking too much places a huge strain on the organ. An overdose can occur quickly, sometimes in as little as 24 hours if more than the maximum is ingested.
Liver damage occurs because paracetamol produces a toxic byproduct when it is metabolised called N-acetyl-p-benzoquinone imine (NAPQI). When paracetamol is taken in the recommended amounts, this byproduct is quickly neutralised by glutathione in the liver. But when too much paracetamol is taken, the amount of NAPQI exceeds the amount of glutathione available to neutralise it. The excess NAPQI then causes damage to liver cells.
Signs and symptoms of liver damage
Some of the signs and symptoms of liver damage from a paracetamol overdose include:
- Yellowing of the skin and whites of the eyes (jaundice)
- Nausea, vomiting and abdominal pain
- Tenderness or pain in the upper right abdomen
- Dark urine and pale stool
- Loss of appetite
- Fatigue and weakness
- Bleeding easily
- Confusion and disorientation
If you experience any of these symptoms after taking more than the recommended dose of paracetamol, seek emergency medical attention immediately. Quick treatment can prevent permanent liver damage.
How much paracetamol is in 1000mg tablets?
As the name suggests, 1000mg paracetamol tablets contain 1000 milligrams of paracetamol in each tablet. This is twice the amount of paracetamol found in standard 500mg tablets.
The 1000mg dose is useful for providing relief from severe or acute pain. However, these high strength tablets still need to be taken carefully and the maximum daily limit adhered to.
Number of 1000mg tablets that can be taken per day
Given that the recommended maximum total daily dose is 4000mg, if taking 1000mg paracetamol tablets this equates to:
- 4 tablets containing 1000mg paracetamol
You should not take more than 4 of the 1000mg tablets within a 24 hour period.
How should you take 1000mg paracetamol tablets?
When taking paracetamol tablets containing 1000mg, the following dosage guidelines should be followed:
- Take 1 tablet every 4-6 hours if needed, up to 4 times a day.
- Always leave at least 4 hours between doses.
- Do not take more than 4 tablets in 24 hours.
- Drink a glass of water when taking the tablets.
- Take the tablets with food to prevent stomach upset.
- Do not double up doses or take extra tablets.
- Stop taking if symptoms persist for more than 3 days and seek medical advice.
Sticking to these recommendations ensures you stay within the safe daily limit and avoid potential liver toxicity.
Timing of doses
Spacing out the doses evenly over 24 hours is important. This allows a steady amount of paracetamol to be in your system to provide consistent pain relief. Leaving at least 4 hours between doses also prevents the previous dose from still being absorbed when taking the next dose.
For example, you might take the 4 daily 1000mg paracetamol tablets at:
- 8am
- 12 noon
- 4pm
- 8pm
This evenly spaces 3 doses over the daytime hours when you are awake, with a fourth dose in the evening.
What are the side effects of too much paracetamol?
As well as liver damage, taking too much paracetamol over the daily limit can also lead to the following adverse effects:
1. Nausea and vomiting
Excessive intake of paracetamol causes nausea and vomiting. This can occur because high concentrations of paracetamol irritate the stomach lining. Vomiting may also be triggered as a protective response by the body to try to expel the overdose.
2. Dehydration
Repeated episodes of vomiting and diarrhea brought about by paracetamol overdose can result in dehydration. Fluids and salts are lost from the body, which need to be replaced.
3. Abdominal pain
Stomach pain may develop 2 to 4 hours after ingesting very high amounts of paracetamol as the drugs starts to damage cells in the small intestine and liver. Upper right abdominal tenderness may signal liver injury.
4. Low blood sugar
An overdose can also cause low blood sugar as paracetamol enhances insulin release and liver damage impairs glucose production. Symptoms of hypoglycemia include tremors, palpitations, and nervousness.
5. Kidney failure
The kidneys can also be affected by paracetamol toxicity. The breakdown products formed can cause damage to kidney tubules, potentially leading to acute kidney failure in severe cases.
What to do if you’ve taken too much paracetamol?
If you realize you’ve taken more than the maximum recommended dose of paracetamol, seek emergency medical help immediately. Swift action can prevent permanent damage occurring.
In the hospital, the following treatments may be given:
- Activated charcoal – this binds to paracetamol in the stomach to help remove it from the body.
- N-acetylcysteine – this helps replenish glutathione stores in the liver to neutralize toxic metabolites.
- Intravenous fluids – to treat dehydration and low blood pressure.
- Liver protectants – drugs like Silymarin may be given to help reduce liver cell damage.
- Pain relievers – to help relieve symptoms of abdominal pain.
With timely treatment, most cases of paracetamol overdose can recover without any permanent liver damage. However, acute liver failure can occur in severe poisoning cases.
Who should be cautious of paracetamol dosage?
While healthy adults can safely take paracetamol at recommended doses, the following groups need to take extra care:
People with liver disease
Those already with liver disease such as viral hepatitis, cirrhosis or alcoholic liver disease have less functioning liver cells. They cannot metabolise paracetamol as efficiently so have lower maximum daily limits.
Long-term alcohol drinkers
Heavy alcohol consumption over many years can increase the risk of paracetamol-induced liver injury. Chronic alcohol use induces a liver enzyme called CYP2E1 that produces more of the toxic NAPQI metabolite.
Elderly people
Older adults may be more susceptible to paracetamol overdose. Liver mass and blood flow decreases with age, so older people cannot detoxify it as effectively. Lower doses may be advised.
Malnourished people
Malnutrition depletes glutathione reserves that help detoxify NAPQI. Paracetamol is more likely to cause toxicity when glutathione stores are reduced.
Genetic differences
Rare cases have involved people with genetic variations in certain liver enzymes being more susceptible to toxicity from standard doses of paracetamol.
How long does paracetamol take to work?
Paracetamol is absorbed quite rapidly, with oral tablets beginning to take effect within 30 to 60 minutes after ingestion. Peak concentrations in the bloodstream are reached in 10 to 120 minutes.
After being metabolised by the liver, paracetamol exerts its pain-relieving effect by blocking COX enzymes and the production of pain signalling prostaglandins in the brain and spinal cord. It takes about 1 to 3 hours for maximum pain relief to be felt after taking a dose.
The total duration of analgesia per dose is generally 4 to 6 hours before re-dosing is required. However, this can vary between individuals based on the rate of absorption and metabolism.
Fast vs slow metabolisers
The speed of paracetamol absorption and clearance from the body differs between people. Those who metabolise it faster are termed ‘fast metabolisers’, while those who metabolise it slower are ‘slow metabolisers’.
In fast metabolisers, paracetamol may start working in 20 to 30 minutes but only last 3 to 4 hours. In slow metabolisers, onset is about 1 hour but duration is up to 6 hours.
Is it bad to take paracetamol every day?
Taking paracetamol occasionally when needed is generally safe. However, routinely taking it every day long-term is not recommended for the following reasons:
Liver damage
Taking the maximum daily dose continuously stresses the liver. Increased risk of liver toxicity has been seen in people taking just 4g daily for prolonged periods.
Kidney damage
Evidence shows regular paracetamol use may increase the risk of chronic kidney disease. The exact mechanism is unclear but may be related to its metabolism.
Rebound headaches
Frequent use can cause medication overuse headaches where the brain becomes sensitized. Headaches may worsen when the drug is stopped.
Reduced efficacy
The pain-relieving effects may wear off over time as tolerance develops. Higher doses may then be needed to get the same effect.
Stomach bleeding
Long-term daily use, especially at maximum doses, raises the risk of gastrointestinal bleeding from ulceration.
For chronic pain conditions, alternatives such as exercise, physiotherapy and anti-inflammatories may be safer options. Seeking medical advice is recommended before taking paracetamol regularly.
Conclusion
The recommended maximum daily dose of paracetamol for adults is 4,000mg, equating to 4 tablets each containing 1000mg. Exceeding this can lead to severe liver damage. When taking 1000mg tablets, no more than 4 should be ingested in a 24 hour period, with at least 4 hours between each dose. Those with liver disease, alcoholism, malnutrition or the elderly require lower doses. While occasional short-term use is generally safe when taken as directed, taking the maximum dose every day long-term can have adverse health effects.
