BackgroundNon‐steroidal anti‐inflammatory drugs (NSAIDs) are commonly recommended for perioperative opioid‐sparing multimodal analgesic treatments. Concerns regarding the potential for serious adverse events (SAEs) associated with perioperative NSAID treatment are especially relevant following gastrointestinal surgery. We assessed the risks of SAEs with perioperative NSAID treatment in patients undergoing gastrointestinal surgery.MethodsWe conducted a systematic review of randomised clinical trials assessing the harmful effects of NSAIDs versus placebo, usual care or no intervention in patients undergoing gastrointestinal surgery. The primary outcome was an incidence of SAEs. We systematically searched for eligible trials in five major databases up to January 2024. We performed risk of bias assessments to account for systematic errors, trial sequential analysis (TSA) to account for the risks of random errors, performed meta‐analyses using R and used the Grading of Recommendations Assessment, Development and Evaluation framework to describe the certainty of evidence.ResultsWe included 22 trials enrolling 1622 patients for our primary analyses. Most trials were at high risk of bias. Meta‐analyses (risk ratio 0.78; 95% confidence interval [CI] 0.51–1.19; I2 = 4%; p = .24; very low certainty of evidence) and TSA indicated a lack of information on the effects of NSAIDs compared to placebo on the risks of SAEs. Post‐hoc beta‐binomial regression sensitivity analyses including trials with zero events showed a reduction in SAEs with NSAIDs versus placebo (odds ratio 0.73; CI 0.54–0.99; p = .042).ConclusionIn adult patients undergoing gastrointestinal surgery, there was insufficient information to draw firm conclusions on the effects of NSAIDs on SAEs. The certainty of the evidence was very low.