What Are The Side Effects Of Acetaminophen And Diphenhydramine?

Hi Dr. Grief, I have had chronic back pain for decades which has no viable surgical remedies except spinal fusion. I found Ibuprofen to work wonders after it was prescribed for me repeatedly, but stomach irritation has made it impossible to use for pain. Recently, I tried Acetaminophen with partial success. After hearing about Diphenhydramine as an adjunct to boost pain relief, I tried it with amazing success. However, after using this combination successfully for months, I have become concerned about the long-term problems that might arise from either Acetaminophen or Diphenhydramine. No complaints at all so far, but need more info. Thanks.