Generally speaking, eating pineapple will not cause bleeding in the stool. If there is bleeding in the stool after eating pineapple, hemorrhoids, ulcerative colitis, intestinal tumors and other diseases are mostly considered, which can be treated by drugs or surgery. 1. Hemorrhoids: caused by congested and enlarged veins in the anal canal or lower rectum, which are prone to rupture and bleed during bowel movements. It can be treated by using medication such as Ma Ying Long Hemorrhoidal Cream, Hydrocortisone or injection of sclerosing agent, or in severe cases, it can also be treated by surgery. 2. Ulcerative colitis: In addition to blood, there is also pus in the stool, which is manifested as mucus, pus and blood stool. Patients can be treated by taking Liuzosulfapyridine, mesalazine, glucocorticoid and azathioprine. 3. Intestinal tumors: such as colon cancer, rectal cancer, etc., the patient may also have the change of stool shape while bleeding in the stool, and then surgery should be considered. If patients have long-term or recurrent symptoms of bleeding in stool after eating pineapple, it is recommended to consult a doctor in time to find out the cause of the disease under the guidance of a professional doctor and actively carry out the treatment. The medication should be taken in strict accordance with the doctor’s instructions, and should not be used on its own, so as not to delay or even aggravate the condition.