The American Gastroenterological Association has released an updated clinical practice guideline on therapeutic drug monitoring in inflammatory bowel disease (IBD). The guideline was designed to help clinicians properly use therapeutic drug monitoring with anti-tumor necrosis factor-α (TNF) agents and thiopurines.

• Among adult patients with active IBD who are taking anti-TNF drugs, use reactive therapeutic drug monitoring to help clinicians decide how to adjust treatment.
• No recommendation regarding routine proactive therapeutic drug monitoring in adults on anti-TNF agents but who have quiescent IBD.
• In adults taking thiopurines for active IBD or who are experiencing adverse reactions that may be caused by thiopurine toxicity, perform reactive thiopurine metabolite monitoring.
• Recommendations are conditional when the evidence supporting the recommendation is of very low quality.