Resmetirom

Resmetirom, sold under the brand name Rezdiffra, is a medication used to treat a form of fatty liver disease. Specifically it is used in the treatment of non-cirrhotic metabolic dysfunction associated steatohepatitis (MASH) (formerly known as nonalcoholic steatohepatitis NASH). It is structurally similar to the thyroid hormone triiodothyronine and acts as an agonist of the thyroid hormone receptor beta (NR1A2). The most common side effects include diarrhea and nausea. Resmetirom was approved for medical use in the US in March 2024, and in the European Union in August 2025. The US Food and Drug Administration considers it to be a first-in-class medication.