Aspirin vs Ibuprofen: what is the difference?
Aspirin and ibuprofen are both NSAIDs, but aspirin disables the COX enzyme permanently while ibuprofen lets go, so its effect fades as it clears.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Drawn the same way round on the skeleton they share. Aligned; 14 atoms differ, too many to mark as one group.
Side by side
| Aspirin | Ibuprofen | |
|---|---|---|
| Molecular weightCalculated PubChem | 180.16 g/molC9H8O4 | 206.28 g/molC13H18O2 |
| Hydrogen-bond donorsCalculated PubChem | 1 | 1 |
| Half-life in the bodyEditorial MoleculeFinder curated | Not recorded | about 2 h |
| Where each turns upEditorial MoleculeFinder food and product lists |
|
|
| Also sold asEditorial MoleculeFinder curated | Bayer, Bufferin, Ecotrin | Advil, Motrin, Nurofen |
| FamilyEditorial MoleculeFinder curated | Over-the-counter medicines, NSAIDs, Non-opioid painkillers | Over-the-counter medicines, NSAIDs, Non-opioid painkillers |
| Everyday groupEditorial MoleculeFinder curated | OTC medicine | OTC medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Carboxylic Acids, Aromatics, Esters | Carboxylic Acids, Aromatics |
| Hazard labelReported ECHA via PubChem | Warning | Warning |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 200 mg/kgpure aspirin, rat, oral | 636 mg/kgpure ibuprofen, rat, oral |
| A single acute animal measure. It ranks nothing about human safety. | ||
Sources and notes
- Molecular weightcomputedPubChemComputed from the structure; the formula is under each weight.
- Hydrogen-bond donorscomputedPubChemThe hydrogens on nitrogen or oxygen that each molecule can lend to a hydrogen bond, counted from its structure.
- Half-life in the bodyfrom sourceMoleculeFinder curatedIn a typical adult: the time the body takes to clear half of it.
- Where each turns upfrom sourceMoleculeFinder food and product listsEach amount is an editorial figure from our lists, not a measurement of any one product. Each mark is set by hand on the list, never inferred.
- Also sold asfrom sourceMoleculeFinder curated
- Familyfrom sourceMoleculeFinder curated
- Everyday groupfrom sourceMoleculeFinder curated
- Chemical groupscomputedFound by rule (RDKit)Each group is found in the structure by a chemical pattern.
- Hazard labelfrom sourceECHA via PubChem
- Oral LD50from sourceHSDB via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Identifiersfrom sourcePubChemPubChem CID 2244 (Aspirin) and 3672 (Ibuprofen).
In more detail
Both carry a carboxylic acid on an aromatic ring, so they are far closer relatives than either is to acetaminophen. The difference is reversibility. Aspirin acetylates the enzyme permanently, so its effect on platelets outlives the molecule in the blood, which is the basis of its use in cardiology. Ibuprofen binds and lets go, so its effect fades as it clears, with a half-life near 2 hours. Ibuprofen is also the more potent anti-inflammatory at the doses people actually use, and it is the newer molecule by seventy years. Reported oral LD50 in rats is 200 mg/kg for aspirin and 636 mg/kg for ibuprofen.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Aspirin and Ibuprofen?
- Aspirin and ibuprofen are both NSAIDs, but aspirin disables the COX enzyme permanently while ibuprofen lets go, so its effect fades as it clears.
- Is Aspirin bigger than Ibuprofen?
- Ibuprofen is the heavier molecule, 206.28 g/mol against 180.16 g/mol for Aspirin. Aspirin is C9H8O4 and Ibuprofen is C13H18O2.
- Which has the lower reported LD50, Aspirin or Ibuprofen?
- Aspirin, at 200 mg/kg (oral, rat), against 636 mg/kg (oral, rat) for Ibuprofen. 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.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.