Alternating paracetamol and ibuprofen without mistakes
Alternating is sometimes used when one medicine does not bring relief. Guidelines do not recommend it routinely because the main risk is a dosing mistake. If you do it, follow a written plan, not memory.
Last updated: 24 September 2026
The rule
Each medicine keeps its own interval: paracetamol at least 4 h after the previous paracetamol, ibuprofen at least 6 h after the previous ibuprofen. Leave about 3 hours between the two medicines. Never give both at once "to be sure".
Sample schedule
| Time | Medicine | Note |
|---|---|---|
| 20:00 | paracetamol | weight-based dose |
| 23:00 | ibuprofen | 3 h after paracetamol |
| 02:00 | paracetamol | 6 h after previous paracetamol ✓ |
| 05:00 | ibuprofen | 6 h after previous ibuprofen ✓ |
| 08:00 | paracetamol | 3rd paracetamol of the day |
Only give a dose if the child actually needs it — do not wake a sleeping child for the schedule.
When it makes sense
- Fever returns before the first medicine's interval is over and the child is clearly distressed.
- A doctor recommended it for a specific illness.
When not
- Under 3 months, dehydrated, chickenpox — ibuprofen is out, so alternating does not apply.
- Two caregivers giving medicine without a shared log. The biggest risk is a double dose of the same medicine.
How to avoid mistakes
Write down time, medicine and millilitres for every dose in one place both parents can see. What counts is the interval of the same medicine, not "since the last medicine of any kind".
These numbers are conversions from leaflets and guidelines. Before giving a medicine, confirm them at the source:
- NHS: paracetamol for children · NHS: ibuprofen for children
- NICE NG143 — fever in under 5s · AAP HealthyChildren.org
- Polish medicines register (URPL) — official leaflets of the products listed here
- Your own country's medicines regulator and the leaflet in the box always take precedence.
Don't want to calculate and write this down every time?
Oh Fever does it from your child's profile and the product you use: it converts the leaflet dose to weight, counts down to the next dose and watches the daily limit — on iPhone and Apple Watch. Free for one child.
Read next
American Academy of Pediatrics — Medications used to treat fever
NICE NG143 — Fever in under 5s
NHS — Paracetamol for children
NHS — Ibuprofen for children
This content is for information only and does not replace your doctor or the medicine leaflet. Doses on this page are the mg/kg ranges from manufacturers' leaflets converted to body weight. Check the strength on the package before giving any medicine. For high fever, any fever in an infant under 3 months, or worrying symptoms, contact a doctor.