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[Pharmacology](https://durgical.com/en/pharmacology/) · [Bile acids](https://durgical.com/en/pharmacology/classes/bile-acids/)

# Ursodeoxycholic acid

A natural bile acid that makes bile dissolve cholesterol. It treats primary biliary cholangitis and can slowly dissolve small cholesterol gallstones.

Updated 2026-11-01

- Class: [Bile acids](https://durgical.com/en/pharmacology/classes/bile-acids/)
- Target: Bile composition (cholesterol saturation and bile acid pool)
- ATC code: A05AA02

Also called: Ursodiol, UDCA

## Mechanism of action

Ursodeoxycholic acid lowers the liver's synthesis and secretion of cholesterol into bile and reduces intestinal cholesterol absorption. In bile it carries cholesterol in micelles and disperses it as liquid crystals, so bile changes from stone-forming to stone-dissolving. In cholestatic liver disease it also replaces more toxic bile acids in the bile acid pool.

- Lowers cholesterol secretion from the liver into bile
- Carries cholesterol in micelles and liquid crystals
- Bile becomes unsaturated and slowly dissolves cholesterol stones
- Replaces more toxic bile acids in cholestatic disease

## Pharmacokinetics

**Absorption**
Well absorbed in the small bowel; strong first-pass uptake by the liver

**Distribution**
Concentrated in bile and the gallbladder; little reaches the systemic circulation

**Metabolism**
Conjugated in the liver with glycine or taurine; colonic bacteria convert part of it to lithocholic acid

**Elimination**
Enterohepatic circulation, with losses mainly in the stool

## Indications

- Dissolution of radiolucent, non-calcified gallbladder stones in patients with high surgical risk or who decline surgery [Gallstones (cholelithiasis) →](https://durgical.com/en/conditions/gallstones/)
- Prevention of gallstones in people with obesity who are losing weight rapidly
- Primary biliary cholangitis [Primary biliary cholangitis →](https://durgical.com/en/conditions/primary-biliary-cholangitis/)

## Adverse effects

### Common

- Diarrhoea
- Indigestion and abdominal pain
- Nausea or vomiting
- Headache
- Hair loss

### Serious (rare, important)

- Enteroliths (bezoars) causing obstruction in patients with intestinal narrowing or stasis
- Allergic reactions
- Worsening liver tests in some patients with liver disease

## Contraindications

- Calcified or radiopaque stones and radiolucent pigment stones (they do not dissolve)
- Need for cholecystectomy: persistent acute cholecystitis, cholangitis, biliary obstruction, gallstone pancreatitis or biliary-intestinal fistula
- Allergy to bile acids

## Key interactions

**Bile acid sequestrants (cholestyramine, colestipol)**
Bind it in the gut and reduce its absorption

**Aluminium-based antacids**
Adsorb bile acids and may reduce its effect

**Oestrogens, oral contraceptives and clofibrate**
Increase cholesterol secretion into bile and can counteract gallstone dissolution

## What is monitored

- Liver tests (AST, ALT, alkaline phosphatase, GGT, bilirubin) at the start and regularly
- Ultrasound to confirm gallstone dissolution
- Obstructive symptoms in patients with bowel narrowing

## Administration and safety

- Taken by mouth with food, in divided doses as prescribed.
- Spaced from bile acid sequestrants and aluminium antacids.
- Gallstone dissolution takes months, and stones can return after stopping.

## Nursing care

- Check that baseline liver tests and imaging are available.
- Ask about biliary colic, fever or jaundice, which may need surgery instead.
- Review the medication list for sequestrants, aluminium antacids and oestrogens.
- Teach that the benefit is slow and that follow-up ultrasound and blood tests matter.

## Pregnancy and breastfeeding

Published human data have not shown a risk of birth defects or other harm; the decision is individualised.

## Memory aid

URSOdiol is the «bear» bile acid (ursus = bear) that keeps cholesterol in solution: no stones in the den.

## Test yourself

Think of the answer, then tap the question to see it.

## Which gallstones are candidates for dissolution with ursodeoxycholic acid?

Radiolucent, non-calcified cholesterol stones; pigment and calcified stones are not.

## How does ursodeoxycholic acid help dissolve gallstones?

It lowers cholesterol secretion into bile and keeps cholesterol in micelles and liquid crystals, so bile becomes unsaturated.

## Which drugs increase biliary cholesterol and can counteract it?

Oestrogens, oral contraceptives and clofibrate.

## Which chronic liver disease is a main indication?

Primary biliary cholangitis.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/ursodeoxycholic-acid/)

## Related conditions

- [Gallstones (cholelithiasis)](https://durgical.com/en/conditions/gallstones/)
- [Primary biliary cholangitis](https://durgical.com/en/conditions/primary-biliary-cholangitis/)

[← Back to the class: Bile acids](https://durgical.com/en/pharmacology/classes/bile-acids/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - URSODIOL capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a061bb07-a85d-4b08-877f-ce02156f0de7) (DailyMed (U.S. National Library of Medicine), 2023); [DailyMed - URSODIOL tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a3c98080-0a4d-4a93-8dcb-02ab8533050b) (DailyMed (U.S. National Library of Medicine), 2026); [Ursodiol: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a699047.html) (MedlinePlus (U.S. National Library of Medicine), 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=A05AA) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/ursodeoxycholic-acid/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/ursodeoxycholic-acid/