SHEET /vs/ibuprofen-vs-naproxen · COMPARISON
Ibuprofen vs Naproxen: what is the difference?
How they differ
These are the closest pair on the OTC shelf: both NSAIDs, both propionic acid derivatives, both blocking COX. The practical difference is time. Ibuprofen has a half-life near 2 hours and naproxen near 14, which is why one is taken through the day and the other is sold as a twice-daily tablet under the name Aleve. Naproxen is the heavier molecule at 230.26 against 206.28 and carries an extra ether group on a naphthalene ring rather than ibuprofen's simple benzene. Reported oral LD50 sits at 636 mg/kg in rats for ibuprofen and 1234 mg/kg in mice for naproxen, measured in different species, so the two numbers are not directly comparable.
Side by side
| Ibuprofen | Naproxen | |
|---|---|---|
| Formula | C13H18O2 | C14H14O3 |
| Molecular weight | 206.28 g/mol | 230.26 g/mol |
| Family | Over-the-counter medicines, NSAIDs, Non-opioid painkillers | Over-the-counter medicines, NSAIDs, Non-opioid painkillers |
| Everyday group | OTC medicine | OTC medicine |
| Functional groups | Carboxylic Acids, Aromatics | Carboxylic Acids, Aromatics, Ethers |
| GHS signal wordThe supplier-filed hazard label, not a statement about ordinary use. | Danger | Danger |
| Oral LD50A single acute animal measure. It ranks nothing about human safety. | 636 mg/kg (oral, rat) | 1,234 mg/kg (oral, mouse) |
| Half-life | 2 h | 14 h |
| Also sold as | Advil, Motrin, Nurofen | Aleve |
| CAS number | 58560-75-1 | 22204-53-1 |
| PubChem CID | 3672 | 156391 |
Structural similarity 0.42 of 1, computed as a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.
Common questions
- What is the difference between Ibuprofen and Naproxen?
- These are the closest pair on the OTC shelf: both NSAIDs, both propionic acid derivatives, both blocking COX. The practical difference is time. Ibuprofen has a half-life near 2 hours and naproxen near 14, which is why one is taken through the day and the other is sold as a twice-daily tablet under the name Aleve.
- Is Ibuprofen bigger than Naproxen?
- Naproxen is the heavier molecule, 230.26 g/mol against 206.28 g/mol for Ibuprofen. Ibuprofen is C13H18O2 and Naproxen is C14H14O3.
- Which has the lower reported LD50, Ibuprofen or Naproxen?
- Ibuprofen, at 636 mg/kg (oral, rat), against 1,234 mg/kg (oral, mouse) for Naproxen. An LD50 is one acute animal measurement, and the two here were not necessarily measured in the same species, so it is a data point rather than a ranking of how dangerous either is to a person.