Allopurinol side effects
You may notice some mild side effects you start taking allopurinol. Common side effects include nausea, upset stomach, diarrhea, mild drowsiness, or a rash. Some people may also feel tired, notice changes in taste, or experience occasional headaches or muscle aches. It’s not unusual to have more gout attacks during the first few months as uric acid levels begin to shift in your body. This usually gets better with continued use.
Serious side effects from allopurinol are rare, but it’s important to know what to watch for. Contact your healthcare provider immediately if you notice severe skin reactions, such as painful, blistered skin, a peeling, rapidly spreading rash, or widespread redness. Call your doctor if you have swollen glands, trouble breathing, jaundice (yellowing of the skin or eyes), irritated eyes, unusual bruising or bleeding, dark urine, or persistent fever.
Although uncommon, allopurinol can cause serious skin reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Both require urgent medical attention.