What are the side effects of acetaminophen 500 mg?

Rare side effects of acetaminophen include sore throat, unusual bruising, lower back or side pain, jaundice and bloody or cloudy urine, according to Mayo Clinic. Use of the fever and pain reducer should be limited to 4,000 milligrams over a 24-hour period to reduce the risk of liver damage.

Symptoms of overdose include diarrhea, increased sweating, loss of appetite, nausea or vomiting, stomach cramps or pain and swelling, pain or tenderness in the upper abdomen or stomach area, cites Mayo Clinic. The Food and Drug Administration has stated that in rare cases, patients using acetaminophen are prone to severe skin reactions, including rash and blisters causing widespread damage to the skin.