Hi, Paracetamol is a very safe and effective medication for relieving pain, but especially in high doses, may cause abdominal pain or discomforts in some patients. Antibiotics like penicillin also may cause abdominal discomforts in some people when taking this medication. But, NSAIDS like ibuprofen induced gastrointestinal symptoms are the most common side effects among the medications. If ibuprofen is consumed in large doses, then less prostaglandin is secreted due to less production of prostaglandin. This may increase the secretion of stomach acid and stomach lining can be irritated, causing weird feeling in the stomach like a sore. Ibuprofen can develop ulcers in the stomach. Taking ibuprofen with water and food may reduce this discomfort in the stomach. Taking antacid or anti ulcerant along with ibuprofen also can be helpful to get rid of stomach discomforts. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician