The risk of serious complications from aspirin and ibuprofen, including bleeding ulcers, is 7 per thousand.

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Separately, Celebrex's stomach benefit has also come under question, as Pfizer's own big trial was unable to prove that its Celebrex avoided the most serious complication of the older drugs, bleeding ulcers.

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Esophagitis can also trigger esophageal bleeding or ulcers after frequent exposure of the esophagus to stomach acid.

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Moreover, he says, aspirin may have more side effects--it can cause ulcers or intestinal bleeding.

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