Paracetamol and ibuprofen are the two medicines used most often for pain and fever, and both are well tolerated at label doses. The more useful safety question with fever is not which tablet to take but whether the fever needs assessing at all.
Fever is a symptom, not a diagnosis. Treating it makes someone more comfortable; it does not treat the cause. A tablet that brings a temperature down is not evidence that whatever is causing it can be ignored.
Common side effects of this pharmacy medicine or category
- Paracetamol: side effects are uncommon at label doses. Occasionally nausea or rash.
- Ibuprofen: indigestion, stomach pain, nausea, and effects on kidneys and blood pressure with prolonged use.
- Combination products add whatever else they contain, commonly caffeine, an antihistamine or a decongestant, each with its own effects.
Taking ibuprofen with food reduces stomach discomfort. Keeping fluids up matters with fever generally, and particularly if taking ibuprofen, because dehydration is what turns an ordinary dose into a kidney risk.
Interactions and duplicate-ingredient risks
This is where most avoidable harm happens with fever. Someone feeling unwell reaches for a flu remedy, then adds a paracetamol tablet for the headache, without either pack making it obvious that both contain paracetamol.
Read the active ingredients on every product before combining anything. See taking two medicines with paracetamol and paracetamol in cold and flu tablets.
Alternating paracetamol and ibuprofen is sometimes advised, particularly for children, but the two schedules have to be tracked separately. Write down what was given and when, because that is exactly what gets confused when someone is up during the night.
Children, pregnancy, older adults and chronic medicine cautions
Children. Dose by weight rather than age where possible, use the measuring device supplied, and note that syrups come in different strengths, so the same spoonful is not the same dose across products. See children’s paracetamol and children’s ibuprofen.
Get medical help for a child with fever who is under three months old, is difficult to wake or unusually drowsy, has a rash that does not fade when pressed, has a stiff neck or dislikes light, is breathing rapidly or with difficulty, is not passing urine, or is not improving. Do not wait to see whether the medicine works.
Pregnancy. Paracetamol is usually preferred; anti-inflammatories are generally avoided. Older adults face higher stomach and kidney risk from ibuprofen.
Warning signs and overdose concerns
Paracetamol overdose is an emergency and often causes no symptoms at first. Someone can feel entirely well for a day while liver damage is underway, and treatment works best started early. If more than the labelled dose may have been taken, go to an emergency unit immediately with the packaging, even if the person seems fine.
Also emergency care for: difficulty breathing or facial swelling; a rash that blisters or peels; vomiting blood or black tarry stools; a fever with a rash that does not fade under pressure; or a first seizure.
Questions to ask a pharmacist before using it
- Does anything else I am taking contain paracetamol or an anti-inflammatory?
- What is the correct dose for my child’s weight?
- Can I alternate paracetamol and ibuprofen, and how would I track it?
- How many days of fever before I should see a doctor?
- Is a single-ingredient product better than a combination for this?
Related OTC and medicine-safety guides
- OTC medicine side effects
- Painkiller side effects
- How to read over-the-counter medicine labels
- When to see a doctor about an OTC medicine
- Report an OTC medicine side effect
See also paracetamol, ibuprofen and cold and flu medicine side effects.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.