Start with reduced starting doses (20%-50% of normal dose) if normal starting dose is 2-3 mg/kg/day (e.g., 0.4 – 1.5 mg/kg/day), and adjust doses of azathioprine based on degree of myelosuppression and disease-specific guidelines. At least 2-4 weeks will be required to reach steady-state after each dose adjustment (PMID 20354201, 11302950, 15606506, 16530532).