Anaphylactoid reactions may occur (higher risk in «aspirin triad» (bronchial asthma, aspirin intolerance, rhinitis)). Do not use in patients who experience bronchospasm, asthma, rhinitis, or urticaria with NSAID or aspirin therapy. Use caution in other forms of asthma. Platelet adhesion and aggregation may be decreased (prolong bleeding time). Anemia may occur. NSAIDs associated with increased risk of adverse cardiovascular thrombotic events (myocardic infarction, stroke, new onset or worsening of pre-existing hypertension). Use caution with fluid retention, heart failure, or hypertension. Concurrent administration of ibuprofen, and potentially other nonselective NSAIDs, may interfere with the cardioprotective effect of aspirin. NSAIDs may increase risk of gastrointestinal irritation, inflammation, ulceration, bleeding, and perforation (caution if history of gastrointestinal disease, concurrent therapy with aspirin, anticoagulants, and/or corticosteroids, smoking, use of alcohol, and elderly or debilitated patients). When used concomitantly with ≤325 mg of aspirin, higher risk of gastrointestinal complications. May cause mild photosensitivity reactions. NSAIDs may cause serious skin adverse events (exfoliative dermatitis, Stevens-Johnson syndrome, and toxic epidermal necrolysis). Use contraindicated for treatment of perioperative pain in setting of coronary artery bypass graft surgery. Risk of myocardic infarction and stroke may be increased with use following coronary artery bypass graft surgery. Use with caution in decreased hepatic function. Severe hepatic reactions (e.g. fulminant hepatitis, liver failure) occurred with NSAID use, rarely (higher risk if impaired renal function, dehydration, heart failure, liver dysfunction, consumption of diuretics, and ACE inhibitors, and elderly); not recommended for use in advanced renal disease (long-term NSAID use may result in renal papillary necrosis). The elderly are at increased risk for adverse effects (especially peptic ulceration, CNS effects, renal toxicity) from NSAIDs, even at low doses. Withhold prior to surgical or dental procedures. False-positive urine immunoassay screening tests for benzodiazepines reported and may occur several days after discontinuing oxaprozin.