How to choose between acetaminophen, ibuprofen and aspirin? According to the World Health Organization (WHO), all three drugs are called “class ” antibiotics, which means they are designed to treat mild to moderate infections. But these three antibiotics are not the same. Dr. Gisèle Pickering, medical doctor at the University Hospital of Clermont-Ferrand, explains. Treatment types, target disease, side effects, contraindications… Understand the specifics of our most common side effects and learn how to use them.
Benefits of paracetamol
How does paracetamol work?
Doctors and researchers have long believed that paracetamol acts peripherally, at the site of the pain. In fact, its true role was understood in the : It activates pain-regulating systems in the brain. Recently ofessor Alain Eschalier’s Inserm group discovered a new protein involved in the central antibiotic activity of paracetamol.
What kind of pain?
Paracetamol is considered the first line treatment for all nociceptive pain (pain after an injury such as a cut). It is the first drug that will help with headaches, flu, toothaches, etc. It has also been used as a first-line treatment for osteoarthritis, but a study published in the British Medical Journal in should question this position because it found that paracetamol is not effective in treating osteoarthritis, pain and back pain. 2
What dose?
The dose of paracetamol in children depends on the child’s weight (see leaflet). The recommended daily dose of acetaminophen depends on the child’s weight: approximately 60 mg/kg per day in 4 or 6 divided doses, or 15 mg/kg approximately every 6 hours, or 10 mg/kg every 4 hours.
The usual dose for adults and children weighing over 50 kg (up to 15 years of age) is 1 or 2 500 mg capsules per dose (depending on the severity of the disease), repeated after at least 4 hours if necessary. The daily dose of acetaminophen should not exceed 3 grams or 6 tablets per day. What are its side effects?
Paracetamol has long been considered a completely safe drug with no side effects, which explains its unique status in the field of allergies today. However, studies have shown that excessive use of the drug can cause liver problems. The most recent study, from March 2025showed that long-term use of the drug increases the risk of heart disease.
Dr. Pickering says the results should be treated with caution, especially on a methodological level: “This study is not a meta-analysis, it is a review of eight studies, there is no randomised one, and the data were evaluated,” he added. “In real practice”, he added, “therapeutic use of paracetamol (3 g/day) has not been shown to be harmful” from the negative instructions written by the Pharmacovigilance Centre. “
What are the contraindications?
Apart from the very rare known hypersensitivity to paracetamol, there are very few contraindications to paracetamol. It can be used during pregnancy without harming the fetus. Dr. Pickering said that “the only problem with paracetamol is anticoagulants or AVKs, which are reported by many GPs” and sometimes causes bleeding problems.
Properties of Ibuprofen
How does ibuprofen work? Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID). It regulates the release of prostaglandins, chemicals released by the body when injured, and can reduce pain, inflammation, and fever.
What kind of pain is it for?
If you can’t be treated with acetaminophen (the first thing your doctor would try is acetaminophen) and you don’t have any contraindications to NSAIDs, you can try ibuprofen. This is often the case for people with osteoarthritis, for example (see our video on treating osteoarthritis ), where symptoms can be better treated by taking antibiotics when the pain is present. However, due to side effects, it is best to consult your doctor and not take ibuprofen regularly on your own.
Which dose?
Ibuprofen is suitable for adults and children over 30 kg. The usual dose is 1 tablet (400 mg) per dose, repeated after 6 hours if necessary. In any case, do not exceed 3 tablets per day (i.e. 1200 mg per day). The 400 mg tablet is used for more severe pain or fever, or if the 200 mg ibuprofen tablet does not work.
What are the side effects?
Most are gastrointestinal: In some people, taking high doses of ibuprofen can cause stomach pain, diarrhea, and even stomach pain or gastrointestinal bleeding. Rarely, taking ibuprofen can cause skin irritation (itching, swelling, rash, etc.).
What are the contraindications? Ibuprofen is contraindicated in patients with a history of allergies or asthma caused by ibuprofen use, gastroduodenal ulcers and hepatocellular insufficiency, renal or heart failure, and after 6 months of pregnancy.
Properties of aspirin
How does aspirin work?
Acetylsalicylic acid or aspirin is also part of the NSAID family. It works by limiting the production of prostaglandins, thus reducing the inflammatory process. When the molecule is absorbed from the stomach, it enters the bloodstream and then spreads throughout the body. What kind of pain is it for? “For about three years, aspirin wasn’t used as a first-line treatment because doctors realized that aspirin had a lot of side effects, especially in the stomach, and that it could cause bleeding,” Pickering said. For example, if you have a headache, you don’t need to take an aspirin.
In addition to relieving pain, aspirin has many benefits, including preventing thromboembolic disease, as it promotes blood thinning. In this case, a small amount (25-75 mg) can be taken daily.
What dose?
Aspirin is only used in adults and children weighing over 30 kg. The maximum daily recommendation for adults and children weighing over 50 kg (up to 15 years of age) is 3 g of aspirin or 6 effervescent tablets. The usual dose is 1500 mg effervescent tablets, which can be repeated after at least 4 hours if necessary.
For children weighing 30 to 40 kg (approximately 9 to 13 years), the dosage is 1 effervescent tablet each time, which can be repeated after 6 hours if necessary, and a maximum of 4 tablets per day. For children weighing 41 to 50 kg (approximately 12 to 15 years), the dosage is 1 effervescent tablet each time, which can be repeated after 4 hours if necessary, and a maximum of 6 tablets per day.
What are the side effects?
The main side effect of aspirin is gastritis, an upset stomach that can cause stomach pain, stomach pain, or red blood. In special cases, taking aspirin can cause Reye syndrome, a very rare (for example: 0.08 out of 100,000 children) but very serious condition that affects the brain and liver. 7
What are the contraindications?
Aspirin is contraindicated in pregnant women from the 6th month of pregnancy, in those with a history of stomach or duodenal ulcers or bleeding, or in those with a history of allergic reactions to aspirin use. Do not take aspirin if you have heart, liver or kidney disease, especially if you are an adult. Also, if you get sick during or after surgery, it is best to choose another antibiotic, as aspirin can help with bleeding.