The FDA issued an alert in April 2024 informing health professionals of the (rare) risk of developing intrahepatic cholestasis of pregnancy (ICP) with the use of azathioprine, mercaptopurine and thioguanine - collectively known as thiopurines.

Most reported cases occurred during off-label use for inflammatory bowel disease and the auto-immune condition systemic lupus erythematosus. ICP is characterised by pruritus without a rash and usually present late in the second trimester or in the third trimester. Jaundice is sometimes present. Elevated serum total bile acid concentration is a key finding.

Read the FDA alert here.