For non-malignant conditions, consider alternative non-thiopurine immunosuppressant therapy. For malignant conditions, start with drastically reduced normal daily doses (reduce daily dose by 10-fold) and adjust doses of azathioprine based on degree of myelosuppression and disease-specific guidelines. Allow 4-6 weeks to reach steady-state after each dose adjustment (PMID 16530578, 11302950, 15606506, 16530532, 12477776).