 [ Symptoms ] are there hidden side effects for taking high doses of ibuprofen  i have been taking high doses of ibuprofen for about 2 years now im wondering if there are side effect going on with my body that i am not sure about i thought i had an ulcer a few months ago because my stools were very black and i was in alot of pain im not sure if this has anything to do with it [ Disease ] most helpful answer i do not know anything about your medical history to give you an okay certain types of cancer especially those that may involve the liver and certain types of chemotherapeutic drugs that can cause liver effects may not permit acetaminophen use because your chemotherapy is soooooo important it would be wise to ask this very patient specific question directly to your oncologist do not take acetaminophen until you get the specific okay from your oncologist