Obeticholic Acid

Obeticholic acid is not a longevity drug, and it is no longer an approved treatment in the US or the EU. If you have fatty liver disease with moderate-to-advanced scarring (not cirrhosis), the drugs that did win approval — resmetirom and semaglutide — work by other routes; ask a liver specialist about them.

What it is

Obeticholic acid is a drug that strongly activates FXR (the farnesoid X receptor), a sensor inside liver and gut cells. FXR is the main brake on bile acid production: when it is switched on, the gut releases a hormone, FGF19 (fibroblast growth factor 19), that tells the liver to stop making bile acid and to damp its glucose and fat output. The drug was meant to pull that brake harder, to protect the liver in bile-duct disease and fatty liver disease. The wider biology is on Bile, microbiome and metabolic health.

A provisional approval that the follow-up trial did not confirm

In 2016 obeticholic acid won accelerated approval in the US for primary biliary cholangitis, a disease of the liver's bile ducts. Accelerated approval is provisional: it holds only if a later trial confirms a real benefit.

That trial, called COBALT, did not. Death, liver transplant or signs of advanced liver disease occurred in 28.6% of patients on the drug and 28.9% on placebo.^[1] The comparison is blurred: many placebo patients worked out what they were taking and switched to the commercial drug, and the manufacturer, which funded the trial, argued that analyses allowing for this, and a comparison with patients outside the trial, favoured the drug. Regulators were not persuaded.

• The EU revoked the approval in 2024 because the benefit had not been confirmed.^[2]
• The US FDA went further. It found an excess of liver transplants and deaths among trial patients who had started with early-stage disease, asked the manufacturer to withdraw the drug, and approval ended in November 2025.^[3]

Fatty liver: a biopsy gain the FDA would not accept

The bigger prize was steatohepatitis (MASH, formerly NASH), the inflammatory form of fatty liver disease that can progress to cirrhosis. In a large phase 3 trial, 931 patients with moderate-to-advanced scarring were analysed at 18 months. On the higher dose, 23% improved by at least one stage of scarring against 12% on placebo. The trial's other target, clearing the inflammation itself, was not met. Itching was the main side effect: across everyone treated, about half of patients on the higher dose against about a fifth on placebo.^[4]

The US FDA rejected it for this use twice. The gain was on a biopsy, a stand-in for the outcomes that matter (cirrhosis, transplant, death), and it was offset by itching, rises in cholesterol and the risk of liver injury. It was never approved for fatty liver disease anywhere.

The drugs that followed did no better

• Newer FXR drugs. Cilofexor cut liver fat by about 23% at its top dose over 24 weeks, against essentially no change on placebo, and caused more moderate-to-severe itching — but it did not change liver stiffness or blood markers of scarring.^[5] Neither it nor tropifexor is still being developed for fatty liver disease, and the furthest-along FXR drugs left are only in phase 2.^[6]
• An engineered FGF19. Aldafermin, built to trigger the gut-to-liver brake directly, cut liver fat, but its larger, manufacturer-funded trial in 171 patients missed its main scarring target.^[7]

What won instead

The fatty-liver drugs that were approved don't act on FXR. Resmetirom, a liver-targeted thyroid-hormone mimic, was approved in the US in March 2024 and in the EU in August 2025 for steatohepatitis with moderate-to-advanced scarring, but not cirrhosis. Scarring improved in about 24–26% of patients against 14% on placebo, and LDL cholesterol fell rather than rose.^[8] Semaglutide followed in the US in August 2025 (see GLP-1 agonists).^[9]

Both were approved early, on manufacturer-funded trials, on the same kind of evidence obeticholic acid was turned down on: biopsy improvements. One difference was the side-effect balance: resmetirom lowers LDL, where obeticholic acid raised it. Whether either prevents cirrhosis or death is still being tested.

What to do

1. Don't look for obeticholic acid or other FXR drugs as a metabolic or longevity aid. None is approved for that, and the one that reached the market lost its approval.
2. If you took it for primary biliary cholangitis, talk to your liver specialist about alternatives rather than sourcing it privately.
3. If you have fatty liver, ask about the free FIB-4 score, the recommended first check for scarring, and, if scarring is found, about the approved options; both are covered on Bile, microbiome and metabolic health.

Further reading

• Kowdley KV, et al. COBALT: A Confirmatory Trial of Obeticholic Acid in Primary Biliary Cholangitis With Placebo and External Controls. Am J Gastroenterol 2025 — the confirmatory trial that did not confirm.^[10]
• Younossi ZM, et al. Obeticholic acid for the treatment of non-alcoholic steatohepatitis: interim analysis from a multicentre, randomised, placebo-controlled phase 3 trial. Lancet 2019.^[11]
• Patel K, et al. Cilofexor, a Nonsteroidal FXR Agonist, in Patients With Noncirrhotic NASH: A Phase 2 Randomized Controlled Trial. Hepatology 2020.^[12]
• Harrison SA, et al. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis. N Engl J Med 2024.^[13]
• Prikhodko VA, Okovityi SV. Current Drug Development Pipeline for MASLD and MASH: Focusing on Cardiovascular Comorbidities. Biomedicines 2026.^[14]