Answer
Only under specialist supervision because allopurinol can greatly increase thiopurine exposure and cause life-threatening bone-marrow suppression.
Sources for this answer
- Allopurinol Tablets BP 100mg — Current selected SmPCemc · Summary of Product Characteristics
- Allopurinol 100mg — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.