Table 2.

Causes of allopurinol failure and actions required for success.

Cause	Reasons	Action Required
Failure to control SU	Inadequately dosed, taking regularly	Increase allopurinol dose
	Adequately dosed, taking regularly	Check source of allopurinol to confirm not counterfeit Add or switch to another ULT
	Not taking regularly	Review and address barriers to allopurinol adherence/ persistence, before further dose escalation, adding additional medications, or switching ULT
Failure to control clinical symptoms despite SU control	Incorrect diagnosis	Review diagnosis
	Correct diagnosis, gout flares occurring early in the course of treatment	Continue allopurinol at the dose that controls SU, plus add flare prophylaxis and action plan for flare
	Correct diagnosis, high MSU crystal burden and SU at standard target	May need lower SU target: increase allopurinol dose further or add/switch to another ULT
Failure due to adverse drug reaction to allopurinol	Medication intolerance	Switch to another ULT