Ursodeoxycholic acid dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Ursodeoxycholic acid is an approved bile acid that also protects mitochondria. In people, a small safety study in Parkinson disease is the result worth reading. In mice, it failed the lifespan test.
Evidence grade for Ursodeoxycholic acid: Limited. The rule: people have taken it in a published study, but fewer than 100 of them. The sum on this page: 1 completed trial, 30 people given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 30
- Human studies
- 1
- Found nothing
- 1
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved for primary biliary cholangitis, a long-term liver disease, and to dissolve gallstones in some patients. Not approved for Parkinson's disease or any ageing use.
3 effects reported, 2 unwanted, 1 wanted, by people using it, not a trial
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
UDCA is a bile acid your body already makes. As a prescription drug, it treats a liver disease called primary biliary cholangitis and dissolves some gallstones. It also protects mitochondria, which got it looked at for brain disease and ageing.
What people take it for
- Liver health.
- Guarding the brain, often as its cousin TUDCA.
- A longer life.
What studies in people showed
In 30 people with early Parkinson disease, a year on a high dose was safe. It was built to check safety. The standard movement score did not change. Brain scans hinted it reached its target. In that liver disease, it improves liver blood tests and slows the disease. Nobody has tested it for ageing. Now mice. It did not make either sex live longer.
What people report
Reports, not study results
The good
- Most people handle it well in the studies on this page.
The bad
- Diarrhoea is the most common problem.
- Mild stomach upset was more common on it in the Parkinson study.
Where these come from: From the studies and drug notes on this page. We have no user reports.
My bottom line
A good liver drug. For ageing, one mouse test said no. If you buy TUDCA, know it is a different molecule with its own evidence.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Nothing indexed yet
The 2 citations on this page do not report a result for any of the 36 goals indexed here. Most of what sits here is something else: a listing of a planned study, a study of how the body handles the drug, a safety report or a government record. None of those tests whether it works.
Show full evidence
What is Ursodeoxycholic acid?
Ursodeoxycholic acid is an approved bile acid that also protects mitochondria. In people, a small safety study in Parkinson disease is the result worth reading. In mice, it failed the lifespan test.
Ursodeoxycholic acid (UDCA) is a bile acid the body makes naturally. It is approved for primary biliary cholangitis, a liver disease, and for dissolving gallstones. It turned out to do things beyond the liver. It steadies mitochondria, eases stress in the cell's protein factory and helps stop cells from self-destructing. That made it a candidate for brain diseases and for ageing.
The more interesting test is in people. A study in Parkinson disease was run and published, with a dummy pill and with nobody knowing who got what. That puts this compound in a small group: a drug borrowed for a new use that actually got a proper human study in a brain disease, instead of staying a promising idea forever. That study was built mainly to check safety.
In the NIA mouse lifespan program, it made no clear difference in either sex.
How does Ursodeoxycholic acid work?
UDCA is a water-friendly bile acid. In liver diseases where bile backs up, it pushes out harsher bile acids and gets bile flowing. That is why it is approved. Its wider effects come from steadying the walls of mitochondria. That makes it harder for them to leak cytochrome c, a signal that tells the cell to self-destruct. It also eases stress in the cell's protein factory (the endoplasmic reticulum). A version joined to taurine, called TUDCA, is the form usually studied for brain protection. It is not the same molecule.
What have studies in people found about Ursodeoxycholic acid?
Decades of approved use in liver diseases where bile backs up. Plus a study in Parkinson disease with a dummy pill for comparison, which is more than most borrowed longevity candidates ever get.
- In 30 people with early Parkinson disease, a high dose or a dummy pill for 48 weeks, with nobody knowing who got what: it was safe and well tolerated. The standard movement rating scale showed no difference. Brain scans hinted it reached its target, and walking pace measured by sensors may have improved. It was built to check safety, not to prove it works.
- Established and approved for primary biliary cholangitis, where it improves liver blood tests and slows the disease.
- Approved for dissolving gallstones in some patients.
- Generally well tolerated, with diarrhoea the most common problem.
- No human study has looked at lifespan, healthy years or anything else about ageing.
What this does not tell you: The liver approvals are for one specific liver disease and do not carry over to healthy ageing. Most of the brain protection research uses TUDCA, the taurine-joined form. That is a different molecule, and supplement marketing blurs the two all the time. The only lifespan test found nothing.
The state of the research
This compound shows a pattern worth naming, because it comes up again and again on this site. A drug is approved for one thing. A likely second way it works is found. That idea draws attention. Then the question is whether anybody runs the trial. Most candidates never get there, and float around for years as ideas. This one was actually tested in Parkinson disease, with a dummy pill for comparison, which is the right way to settle the question.
For ageing, the record is simpler: one careful mouse lifespan test, no effect. Anyone taking this or TUDCA to live longer is acting on the idea, not on a result.
The National Institute on Aging runs the Interventions Testing Program at three separate labs: The Jackson Laboratory, the University of Michigan and the University of Texas Health Science Center at San Antonio. It uses UM-HET3 mice, a mixed breed made by crossing four strains, so a result cannot be a quirk of one strain. Compounds go in the food. Both sexes are tested. Each group is big enough to spot about a 10 percent change in lifespan. Results are checked with one test for typical lifespan and another for the longest-lived mice. The failures are published next to the wins. No other ageing research has all of that together. That is why a no from this program means much more than a no from one lab.
The evidence, in charts
Fig. 1a · how many people
30people, across 1 study in people cited here
| Study | People | Share |
|---|---|---|
| Movement Disorders 2023 | 30 | 100% |
The whole total is one study of 30. Counts are the number of people each study on this page says it signed up. That includes studies that only watched people and gave nobody the compound. Studies still signing people up are left out, and only studies cited on this page are counted.
Fig. 1b · evidence mix
1 of 2 sources here is a study in people. The rest is not.
- Study in people · done in people150%
- Animal study · done in animals150%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
Sources here come from just two years, 2016 and 2023.
Too few different years on this page to draw a timeline.
Fig. 3 · legal status at a glance
US
Approved
UK
Approved
AU
Approved
CA
Approved
Approved in all four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 5 · what the molecule is
- Kind of compound
- Small molecule
- Molecule weight
- 392.6 Da. A bile acid, not a peptide.
- Half-life
- Stated in words, not a numbersee the exact wording below
- Chain length
- None on file
Half-life as stated on file: Roughly three and a half to six days for the bile acid pool, with extensive enterohepatic recirculation, so steady state takes weeks.
No amino acid sequence is on file for Ursodeoxycholic acid, which is expected: a small molecule is not built from amino acids.
The studies we cite
- Study in people2023A double-blind, randomized, placebo-controlled trial of ursodeoxycholic acid (UDCA) in Parkinson's disease
This trial was built to check safety, not to find out whether the drug helps. Thirty people with early Parkinson disease took a high dose of ursodeoxycholic acid or a dummy pill for a year, and nobody involved knew which. It was safe, with mild stomach upset more common on the drug. Brain scans suggested it reached the target area and improved energy handling there. Walking pace measured by sensors may have improved. The rating scale doctors normally use found no difference. Larger trials are needed.
30 participants with early Parkinson's disease randomised 2 to 1 to high dose ursodeoxycholic acid or placebo for 48 weeks. The primary outcome was safety and tolerability, not efficacy. MDS-UPDRS part three, the standard motor scale, detected no difference between groups. The positives are a 31P magnetic resonance spectroscopy target engagement signal in the midbrain and a possible sensor based cadence improvement. The authors conclude it is safe and well tolerated and that larger trials are needed. Read this before any mechanistic claim about neuroprotection.
- Animal study2016Longer lifespan in male mice treated with a weakly estrogenic agonist, an antioxidant, an alpha-glucosidase inhibitor or a Nrf2-inducer
In mice. This is the NIA mouse lifespan program run that tested UDCA. It says plainly that neither fish oil nor ursodeoxycholic acid made mice live longer. It is the direct source for the failed lifespan test.
The Interventions Testing Program cohort that tested this compound, reporting verbatim that neither fish oil nor ursodeoxycholic acid extended lifespan. The direct source for the lifespan null rather than a general statement about the programme.
Common questions
Has Ursodeoxycholic acid been tested in people?
Yes. 30 people given it across 1 completed trial cited here, 1 of which found nothing. Ursodeoxycholic acid is an approved bile acid that also protects mitochondria. In people, a small safety study in Parkinson disease is the result worth reading. In mice, it failed the lifespan test.
What is the Ursodeoxycholic acid dosage?
Approved medicine. No human dose established for unlabelled uses. Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose. FDA-approved for primary biliary cholangitis, a long-term liver disease, and to dissolve gallstones in some patients. Not approved for Parkinson's disease or any ageing use.
Is Ursodeoxycholic acid FDA-approved?
FDA-approved for primary biliary cholangitis, a long-term liver disease, and to dissolve gallstones in some patients. Not approved for Parkinson's disease or any ageing use.
Does ursodeoxycholic acid slow ageing?
No evidence supports that. It made no clear difference to lifespan in either sex in mouse testing at several labs. No human study has looked at ageing. Its approved uses are in liver diseases where bile backs up.
Is TUDCA the same thing?
Not quite, and the difference matters. TUDCA is UDCA joined to taurine. It is the form most brain protection research uses, and it is sold on its own as a supplement. Evidence for one does not automatically carry over to the other, and supplement marketing often treats them as the same.
What happened in the Parkinson's trial?
It was finished and published in 2023. 30 people with early Parkinson disease took a high dose or a dummy pill for 48 weeks, with nobody knowing who got what. It was built to check safety, and it was safe. The standard movement rating scale showed no difference. It is the compound's most careful test outside the liver. Read it before accepting any brain protection claim based on the idea alone.