REF-983 · Van Wijck et al., 2012 · Medicine & Science in Sports & Exercise, Vol. · Paper · PubMed

Aggravation of exercise-induced intestinal injury by ibuprofen in athletes

C+thin evidenceMeasured on trained athletesWritten before October 2026, being re-checked

Nonsteroidal anti-inflammatory drugs are commonly used by athletes to prevent anticipated exercise-induced pain. Nine healthy, trained men were studied on four occasions: 400 mg ibuprofen twice before cycling, cycling without ibuprofen, 400 mg ibuprofen twice at rest, and rest without ibuprofen.

Both ibuprofen and cycling raised plasma intestinal fatty acid binding protein (I-FABP), a marker of small-intestinal injury, and the level was highest after cycling with ibuprofen (peak 875 ± 137 pg/mL vs 474 ± 74 after cycling alone). Small-intestinal permeability also rose most after cycling with ibuprofen, and injury and barrier dysfunction correlated (RS = 0.56).

The authors conclude that NSAID consumption by athletes is not harmless and should be discouraged.

Participants

Nine healthy, trained men. Age and fitness are not given in the abstract.

Protocol

Conditions (each participant, four occasions): 1) 400 mg ibuprofen twice before cycling, 2) cycling without ibuprofen, 3) 400 mg ibuprofen twice at rest, 4) rest without ibuprofen intake.
Small-intestinal injury: plasma I-FABP.
Permeability: urinary excretion of orally ingested multisugar test probes (liquid chromatography and mass spectrometry); 0-2 h urinary lactulose/rhamnose ratio.
The cycling bout's duration and intensity are not given in the abstract.

Key Results

Peak I-FABP: 875 ± 137 (cycling with ibuprofen), 474 ± 74 (cycling without), 507 ± 103 (rest with ibuprofen), 352 ± 44 pg/mL (rest without); P < 0.002.
0-2 h urinary lactulose/rhamnose ratio: 0.08 (0.04-0.56) after cycling with ibuprofen vs 0.04 (0.00-0.20), 0.05 (0.01-0.07) and 0.01 (0.01-0.03) in the other three conditions, in the same order.
Intestinal injury and barrier dysfunction correlated significantly (RS = 0.56, P < 0.001).
Both ibuprofen and cycling on their own increased I-FABP.

Practical Application

"Is it fine to take ibuprofen before a hard ride or race?" In nine trained men (crossover), 400 mg of ibuprofen taken twice before cycling produced a higher marker of small-intestinal injury than cycling alone (peak I-FABP 875 vs 474 pg/mL) and the leakiest gut of the four conditions; the authors say NSAID use by athletes should be discouraged. Do not take it pre-emptively.
Exercise injures the gut lining a little on its own, and ibuprofen does so at rest; together the effect was largest. An athlete with gut symptoms in long events who also uses NSAIDs has an obvious first thing to remove.
What it does not show: symptoms were not reported in the abstract, so the step from the marker to cramps, nausea or bleeding is an inference.
Not from this paper: the kidney side of ibuprofen in ultramarathons is REF-892; recovery between sessions is SYNTH-70. Not from a study; the base's own practice: pain that needs a painkiller to train through is a reason to see a clinician, and medication decisions belong to the athlete's doctor.

Limitations

n=9, men only; one dosing scheme (400 mg twice) and one cycling bout whose duration and intensity are not in the abstract.
Marker outcomes (I-FABP, sugar-probe permeability); no symptoms, no performance, no clinical events.
Randomisation and blinding are not described in the abstract; no placebo is mentioned.
Acute only: nothing on habitual or lower-dose use, or on other NSAIDs.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

crossover, n=9; mechanistic, marker outcomes only (no symptoms, no performance)