Side effects from taking allopurinol?

Allopurinol. Most common is skin rash. May precipitate a gout attack during initiation of therapy.
Possible SE's. Some health issues that have been linked to long term Allopurinol use include elevated liver enzymes, hepatitis, jaundice, hepatocellular injury, enlarged liver, blood vessel inflammation & skin problems. However that doesn't mean that you will experience any side effects.