The Medicines and Healthcare products Regulatory Agency (MHRA) has today (3 June 2026) authorised the medicine resmetirom (Rezdiffra) to treat adult patients with metabolic dysfunction-associated steatohepatitis (MASH).
MASH is a liver disease where fat builds up in the liver, which can result in inflammation and damage to the liver cells. It is a result of the progression of nonalcoholic fatty liver disease where liver inflammation, over time, can lead to liver scarring and liver dysfunction.
Resmetirom is used in adults who have experienced inflammation and cell damage, resulting in moderate scarring, consistent with stage 2 fibrosis, or significant scarring, consistent with stage 3 fibrosis.
In patients with MASH, a protein called thyroid hormone receptor beta (THR-β), in a type of liver cell called hepatocytes, is less activated. The medicine works by binding to and activating THR-β. By activating this protein in the liver, resmetirom increases fat breakdown. This reduces the amount of fat stored in the liver which can help reduce inflammation, fibrosis, and improve its function.
The authorisations, of resmetirom 60 mg, 80 mg and 100 mg film-coated tablets, were approved under the International Recognition Procedure (IRP).
Julian Beach, MHRA Executive Director, Healthcare Quality and Access, said
“Resmetirom is the first medicine to be approved for patients with MASH and moderate to advanced liver fibrosis.
“We’re assured that the appropriate regulatory standards for the approval of this medicine have been met and today’s decision reflects the MHRA’s commitment to ensuring patients can access innovative treatments that make a real difference.
“As with any medicine, we will continue to monitor the safety and effectiveness of resmetirom closely.”
This approval is supported by evidence from a main study involving 917 adults with MASH and moderate or advanced liver fibrosis who received either resmetirom or a placebo for 12 months. Depending on the dose, around 26 to 30 per cent of patients receiving resmetirom achieved MASH resolution with no worsening of fibrosis, compared with 10 per cent on placebo. Additionally, 27 to 29 per cent of those receiving resmetirom had an improvement in liver fibrosis with no worsening of MASH, compared with 17 per cent on placebo.
Resmetirom is taken orally. The most common side effects of the medicine (which may affect more than 1 in 10 people) include diarrhoea and nausea.
Anyone who suspects they are having a side effect from this medicine are encouraged to talk to their doctor, pharmacist or nurse and report it directly to the Yellow Card scheme website or by searching the Google Play or Apple App stores for MHRA Yellow Card.
Notes to editors
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These new marketing authorisations were granted on 3 June 2026 to Madrigal Pharmaceuticals EU Limited.
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This product was submitted and approved via the International Recognition Procedure (IRP).
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More information can be found in the Summary of Product Characteristics and Patient Information leaflets which will be published on the MHRA Products website within 7 days of approval.
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Metabolic dysfunction-associated steatohepatitis (MASH) is a result of the progression of nonalcoholic fatty liver disease. For more information, visit non-alcoholic fatty liver disease – NHS
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The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.
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The MHRA is an executive agency of the Department of Health and Social Care.
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