What Is Rezdiffra (Resmetirom)? Uses, Dosage, and What You Need to Know in 2026

On March 14, 2024, the FDA made history by approving Rezdiffra (resmetirom) — the first medication specifically designed to treat nonalcoholic steatohepatitis (NASH), now known as MASH (metabolic dysfunction-associated steatohepatitis), with liver fibrosis. Before this approval, the only treatment options for MASH were diet, exercise, and weight loss. Millions of patients finally had a pharmacologic option.

If you or a loved one has MASH and your doctor has mentioned Rezdiffra, here is everything you need to know about what it is, what it treats, how it's taken, and who qualifies.

What Is Rezdiffra?

Rezdiffra is the brand name for resmetirom, manufactured by Madrigal Pharmaceuticals. It is an oral tablet taken once daily. Rezdiffra belongs to a new drug class called thyroid hormone receptor-beta (THR-β) agonists. It works by targeting a specific receptor in liver cells to reduce fat accumulation, inflammation, and scarring (fibrosis).

Generic name: Resmetirom

Brand name: Rezdiffra

Manufacturer: Madrigal Pharmaceuticals (West Conshohocken, Pennsylvania)

Drug class: Thyroid hormone receptor-beta (THR-β) agonist

FDA approval: March 14, 2024 (accelerated approval)

Controlled substance: No — not a scheduled drug

What Does Rezdiffra Treat?

Rezdiffra is FDA-approved for adults with noncirrhotic NASH (now called MASH) with moderate to advanced liver fibrosis (consistent with Stages F2 to F3). It is used together with diet and exercise.

What does that mean in plain English? MASH is a serious liver condition where fat builds up in the liver, causing inflammation that — over time — leads to scar tissue (fibrosis). If fibrosis progresses far enough, it can become cirrhosis, which can lead to liver failure, liver cancer, or the need for a liver transplant. Rezdiffra is specifically approved for patients who have F2 or F3 fibrosis, meaning they have significant but not yet cirrhotic scarring.

The FDA estimates that approximately 6–8 million people in the United States have MASH with moderate to advanced liver scarring. Before Rezdiffra's approval, there was no medication that could directly address the liver damage — only lifestyle changes.

Who Qualifies for Rezdiffra?

To qualify for Rezdiffra, you must:

Be an adult (18 years or older)

Have a confirmed diagnosis of MASH (via liver biopsy showing inflammation and steatosis)

Have fibrosis stage F2 or F3 (moderate to advanced scarring, without cirrhosis)

Not have decompensated cirrhosis — Rezdiffra is contraindicated in this population

Be committed to making concurrent diet and exercise changes (the drug is approved "in conjunction with" lifestyle modifications)

Dosage and How to Take Rezdiffra

Rezdiffra dosing is based on body weight:

Under 100 kg (220 lbs): 80 mg once daily

100 kg (220 lbs) or more: 100 mg once daily

With certain interacting drugs (moderate CYP2C8 inhibitors): Dose reduced to 60 mg (<100 kg) or 80 mg (≥100 kg)

Rezdiffra is available as oral tablets in 60 mg, 80 mg, and 100 mg strengths. It can be taken with or without food. Take it at the same time each day to establish a routine. Steady-state drug levels are typically reached within 3–6 days of starting.

How Well Does It Work?

In the pivotal MAESTRO-NASH Phase 3 trial (888 patients, 12-month biopsy data):

MASH resolution: 26–27% of patients on 80 mg, and 24–36% on 100 mg achieved MASH resolution — compared to just 9–13% on placebo. Patients taking resmetirom were 2–3 times more likely to see MASH resolution.

Fibrosis improvement: 23–24% on 80 mg, and 24–28% on 100 mg achieved at least one stage improvement in fibrosis — vs. 13–15% on placebo. Patients were 1.5–2 times more likely to see fibrosis improvement.

Liver enzymes: Significant reductions in ALT and AST (liver inflammation markers) were observed starting at month 3.

Lipid benefits: Rezdiffra also reduced atherogenic lipids (LDL, lipoprotein(a)), potentially reducing cardiovascular risk — a significant benefit for MASH patients who have elevated baseline cardiovascular risk.

Where to Fill Your Prescription and How to Get Help

Rezdiffra is only available through specialty pharmacies — not at retail chains. medfinder can help you find which pharmacies near you can fill your Rezdiffra prescription. For information on savings programs to reduce your out-of-pocket costs, see our guide: How to Save Money on Rezdiffra in 2026.