The side effects of taking 800 milligrams of ibuprofen include upset stomach, bloating, gas and mild heartburn, according to Drugs.com. Other possible side effects include itching of the skin or a rash, blurred vision, or ringing in the ears. These are all relatively benign side effects, but individuals should speak with a doctor for more information if any of these occur.
More serious side effects, such as hives, difficulty breathing, or swelling of the face, throat, tongue or lips, require immediate medical attention and indicate an allergic reaction to ibuprofen, according to Drugs.com. Other serious side effects that require medical attention or an immediate phone call to a doctor include shortness of breath, slurred speech, chest pain, yellowing of the skin and swelling of any body parts. Because this medicine can cause serious effects on the stomach and intestines, any signs of bleeding also require medical attention. These include black, bloody or tarry stools and coughing up or vomiting up what looks like coffee grounds.
Drinking alcohol while taking ibuprofen increases the risk of stomach bleeding, according to Drugs.com. Because many other over-the-counter cold, flu and pain medicines contain ibuprofen or other nonsteroidal anti-inflammatory drugs, it is important to check with a pharmacist before taking these medicines while using ibuprofen.