TUDCA safety research

• 33human studies of TUDCA on its own
• 17of them report on side effects
• 2 gthe highest daily dose studied
• 54 wkthe longest published controlled trial

What the studies found, and how much research stands behind it

The research grade measures how much evidence there is and how firm it is. A low grade means a finding is not yet confirmed.

• Side effects at 500–750 mg a day, up to 6 monthsFound: About as common as on UDCA in the largest trial; two 1993 trials found UDCA better toleratedOne double-blind trial of 199 people over 24 weeks, plus smaller onesResearchModerate
• Side effects at 1,750 mg to 2 g a dayFound: Close to placebo overall; digestive ones more frequent on TUDCA in one trial, not statistically significantPlacebo-controlled trials of 20 to 54 peopleResearchEarly
• Taking it for a year or longerFound: Side effects close to placeboTwo placebo-controlled trials of 34 and 20 people; the 18-month trial is unpublishedResearchEarly
• Liver blood tests while taking itFound: No change reportedFive studies that reported them, of 13 to 34 people; kidney tests in one study of 13ResearchEarly
• Side effects after gallbladder removalFound: 2 of 101 on TUDCA, 3 of 102 untreatedOne study without a placebo; the side effects are not describedResearchPreliminary
• People with cirrhosisFound: No side effects reportedOne trial of 23 peopleResearchPreliminary
• Pregnancy and breastfeedingFound: Not yet testedNo published study in people; the labels advise against useResearchNot yet studied
• Interactions with other medicinesFound: Not yet testedThe labels list possible interactions; no study in people has been designed to test themResearchNot yet studied
• ChildrenFound: No side-effect data in the published summaryOne trial in 22 newborns, reported for its effect on the liverResearchPreliminary
• Kidney diseaseFound: Not yet testedNo published study in peopleResearchNot yet studied

• Strong
• Moderate
• Early
• Preliminary
• Not yet studied

Research grades are ours, made on the scale described in “How we did this review”. No question about TUDCA has yet reached “Strong”.

Doses used in studies

TUDCA has been given in two ways. Several of the older Italian studies, like the medicine labels, set the dose by body weight; others, and most studies since 2010, used a fixed daily dose. Below, every dose is shown as the study reported it, and the two kinds are kept apart.

Fixed daily doses

• After gallbladder removal (Croce 1993)500 mg
• Gallstones (Duan 2022)500 mg
• Liver trials, 1996–2016500–1,500 mg
• Single doses and absorption studies1,000–1,500 mg
• Metabolism trials, 2010–20251,750 mg
• Ulcerative colitis (Lamm 2025)1,750–2,000 mg
• ALS and multiple sclerosis trials2,000 mg

05001,0001,5002,000mg a day

Shaded: the usual daily dose on the Italian and Turkish labels, 250–750 mg

Doses set by body weight

By body weight, as the studies reported it: 3.5–16.6 mg per kg a day (Muraca 1995); 5–10 mg per kg (the labels; Gao 2022); 10 mg per kg (Gallo 1993, Portincasa 1996, Hepatology Research 2002); 12–15 mg per kg (Ferri 1993); 20 mg per kg (Hardison 1984, healthy men); 30 mg per kg (Heubi 2002, newborns).

Each dose as the study reported it. Sources: the studies listed in “All 33 studies”, and the Tudcabil and Taurolite labels.^[1,2]

• Digestive and liver studies mostly used 500–750 mg a day, the range on the labels. One study in primary biliary cholangitis compared 500, 1,000 and 1,500 mg a day.^[11]
• Trials in metabolism, ulcerative colitis, ALS and multiple sclerosis used 1,750 mg to 2 g a day.^{[4,5,12,13,14,15]} An Italian ALS registry recorded doses below and above 1,000 mg a day.^[16] No study of TUDCA on its own used more than 2 g a day.
• By body weight, adult studies used 3.5 to 20 mg per kg a day,^[17,18] and one study in newborns used 30 mg per kg a day.^[19]
• How it was taken. The labels give the dose in divided doses after meals.^[1,2] Trials used one to three doses a day. The 18-month ALS trial gave it 10–15 minutes after a meal,^[20] and one metabolism trial with breakfast, lunch and dinner.^[21]

Both labels say to lower the dose if diarrhea occurs and to stop if it continues.^[1,2] The 18-month ALS trial allowed the same: 1 g a day for up to two weeks after diarrhea, to allow time to adapt.^[22]

Side effects in the trials

Trials record every health problem that occurs while people take part, whether or not the treatment caused it. This page calls these side effects, and says where the investigators judged them related to the treatment. Of the 33 studies, 17 give some information on side effects, and seven trials give numbers for both TUDCA and a comparison group. Those seven are shown here.

Croce 1993 · after gallbladder removal, 3 months · any side effect^[7]

• TUDCA2/101
• No treatment3/102

Ma 2016 · primary biliary cholangitis, 24 weeks · any side effect^[3]

• TUDCA44%
• UDCA40%

Ladakis 2025 · multiple sclerosis, 16 weeks · any side effect^[4]

• TUDCA10/26
• Placebo7/21

Elia 2016 · ALS, 54 weeks · side effects judged related to the study medicine^[5]

• TUDCA2/15
• Placebo3/14

NCT01877551 · HIV and insulin resistance, 30 days · any side effect posted^[12]

• TUDCA1/13
• Placebo0/14

NCT02218619 · type 1 diabetes, 12 months · any side effect posted^[13]

• TUDCA0/10
• Placebo0/10

Kars 2010 · obesity, 4 weeks · any side effect posted^[21]

• TUDCA0/10
• Placebo0/10

People with at least one side effect, out of the people in each group, as each trial reported it; Elia 2016 gives events judged related, and Ma 2016 gives percentages only. Bars run to 50%. Where a test was reported (Ma 2016, Ladakis 2025), the difference was not statistically significant.

The side effects named are mostly digestive:

• In multiple sclerosis (2 g a day for 16 weeks), 10 digestive side effects were recorded among 26 people on TUDCA and 4 among 21 on placebo, a difference that was not statistically significant (p=0.2). On TUDCA they were diarrhea (3), nausea or vomiting (2), indigestion or reflux (2), abdominal pain (2) and the cholangitis described below.^[4]
• In ALS (2 g a day for 54 weeks), mild diarrhea was reported in 2 people on TUDCA and 2 on placebo. Blood counts and chemistry, including liver tests, did not change in either group.^[5]
• In ulcerative colitis (1,750–2,000 mg a day for 6 weeks, no comparison group), 6 of 13 people had nausea or indigestion and 2 had one or two more bowel movements a day for 3 and 14 days. Two lowered the dose to 1,000 mg a day; one later went back to 1,750 mg. Kidney and liver tests and blood counts did not change.^[15]
• In primary biliary cholangitis (750 mg a day for 24 weeks), side effects were judged related to the medicine in 4 of 129 people on TUDCA (diarrhea, itching, rash and period pain) and 3 of 70 on UDCA.^[3]

Ladakis 2025

Nervous system · safety appraisal

People

54 people with progressive multiple sclerosis (47 in the safety analysis)

Design

Randomized, double-blind, placebo-controlled

Compared with

Placebo

Dose

2,000 mg/day (1 g twice a day)

Length

16 weeks

Side effects

Any side effect 38% vs 33% on placebo (p=0.77); digestive 38% vs 19% (p=0.2), including diarrhea 3 of 26 vs 0 of 21

Serious events

1 on TUDCA: cholangitis, hospitalized, recovered; judged unlikely related

Stopped for side effects

1 on TUDCA, 0 on placebo (registry)

Safety data from

Full text; registry results

Source: ^[4,23] Ladakis DC, Harrison KL, Smith MD, et al. Bile acid metabolites predict multiple sclerosis progression and supplementation is safe in progressive disease. Med. 2025;6(3):100522.

Against UDCA, results differ by study. In the largest double-blind trial, 199 people, health problems were recorded about as often on TUDCA as on UDCA (44% and 40%), and 94% of them were judged unrelated to either medicine.^[3] Two Italian trials from 1993, with 25 and 31 people who finished, found UDCA better tolerated; neither summary gives counts.^[24,25] A crossover study of 23 people at 500 mg a day and a cirrhosis trial of 23 people at 750 mg a day each reported that “no patient complained of side effects”.^[26,27]

Does dose matter? In an Italian ALS registry, 20 side effects were recorded in 18 people: 5 among the 20 taking under 1,000 mg a day and 15 among the 66 taking 1,000 mg or more, which the authors describe as no difference.^[16] The dose-response trial in primary biliary cholangitis reported diarrhea as the only side effect, without saying at which doses.^[11]

Serious events and deaths

Across the controlled trials that report serious events, one person on TUDCA had a serious event other than death from their illness:

• Multiple sclerosis trial: one person on TUDCA was hospitalized with cholangitis, an inflammation of the bile ducts, and recovered. The trial's safety board judged it unlikely to be related. Scans showed long-standing abnormalities of the bile ducts and a gallbladder that did not empty, and the authors suggested excluding people with known bile-duct abnormalities from future TUDCA trials.^[4] The trial's registry record lists the same event as cholecystitis, an inflammation of the gallbladder.^[23]
• No serious events were recorded in the 199-person liver trial,^[3] the ulcerative colitis study,^[15] or the three trials whose results are posted on ClinicalTrials.gov.^[12,13,21]
• Deaths in two trials were judged unrelated to TUDCA. In the ALS trial, 1 person on TUDCA and 3 on placebo died of respiratory failure.^[5] After liver transplants, 5 of 29 people followed long term died, 3 in the TUDCA group, “none of which was related to treatment”.^[28]
• In the Italian ALS registry, which had no comparison group for side effects, two side effects needed hospital care and resolved after TUDCA was stopped. The paper does not say which they were, and attributes no deaths to TUDCA.^[16]

Long-term use

Most studies ran for six months or less. At least five gave TUDCA for a year or longer.

• TUDCA-ALS18 mo
• ALS registry449 d
• Elia 201654 wk
• NCT0221861912 mo
• Angelico 199912 mo
• Ma 201624 wk

How long people took TUDCA in each study. Grey: results not yet published. TUDCA-ALS: ALS, 2 g a day, planned for 18 months, with about half of the participants reaching 18 months. ALS registry (Zucchi 2023): observational, an average, with 44 of 86 people taking it for more than a year. Elia 2016: ALS, 2 g a day. NCT02218619: type 1 diabetes, 1,750 mg a day. Angelico 1999: after a liver transplant, 500 mg a day. Ma 2016, the largest double-blind trial with published results: primary biliary cholangitis, 750 mg a day. Sources:^{[3,5,6,13,16,20,28]}

In the 12-month type 1 diabetes trial, at 1,750 mg a day, no side effects were posted in either group of 10, and no one had abnormal liver tests at 6 and 12 months, or 6 months after stopping.^[13] In the Italian registry, 44 of 86 people took TUDCA for 12 months or longer. Of all 86, 7 stopped because of side effects (3 for diarrhea, 2 for abdominal pain, 2 for skin eruptions) and 13 lowered the dose.^[16] The full results of the ALS trial planned for 18 months have not been published; about half of its participants reached 18 months.^[6]

After gallbladder removal

One controlled study gave TUDCA after gallbladder removal: 500 mg a day in 203 adults with indigestion, checked at one, two and three months. Side effects were reported in 2 of 101 people on TUDCA and 3 of 102 who took nothing. The published summary does not say what they were.^[7] Its results for indigestion are reviewed in our review of the human evidence.

The Turkish label lists “biliary dyspepsia with or without cholecystectomy” among TUDCA's uses.^[2] No study has measured how TUDCA is absorbed or handled by people without a gallbladder. Two trials excluded people who had had their gallbladder removed: the 54-week ALS trial^[5] and the ulcerative colitis study.^[29] The 18-month ALS trial excluded several gallbladder and bile-duct conditions.^[22]

What the medicine labels say

TUDCA is a prescription medicine in Italy, where the medicines regulator lists Tudcabil and Tauro as “subject to medical prescription”,^[30] and a licensed medicine in Turkey. It is also sold as a medicine in China, where we could not read an official label.^[3,31] The official product information in Italy and Turkey sets out who should not take it, what to watch for and which medicines to keep apart from it. The labels were written for the treatment of gallstones and, in Turkey, liver disease, under a doctor's supervision.^[1,2,32]

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Label section	Tudcabil (Italy)	Tauro (Italy)	Taurolite (Turkey)
Status	Prescription medicine, Italy, since 1991	Prescription medicine, Italy, since 1991	Licensed medicine, Turkey, since 2007
Dose	5–10 mg per kg a day, usually 250–750 mg, in divided doses after meals	5–10 mg per kg a day, usually 250–750 mg, in divided doses after meals	5–10 mg per kg a day, usually 250–750 mg, in divided doses after meals with some liquid
Must not be used	Allergy to bile acids; pregnancy; active stomach or duodenal ulcer; acute inflammation of the gallbladder or bile ducts; blocked bile ducts; frequent biliary colic; calcified stones; a gallbladder that empties poorly	Allergy to the ingredients; active peptic ulcer; pregnancy; calcified stones; conditions that call for gallbladder removal, such as cholangitis or blocked bile ducts	Allergy; active stomach or duodenal ulcer; pregnancy; calcified stones; frequent biliary colic; biliary infection; blocked bile ducts; a gallbladder that contracts poorly; severe pancreatic or bowel disease
Best avoided	Biliary infection; severe pancreatic disease; removal of the ileum, an ileostomy or regional ileitis	“Generally contraindicated” with the same conditions	Listed under “must not be used”
Liver tests	AST, ALT and GGT every 4 weeks for 3 months, then every 3 months	Not stated	AST, ALT and GGT every month for 3 months, then every 3 months
If diarrhea occurs	Lower the dose; stop if it persists	Not stated	Lower the dose; stop if it continues
Other medicines	Keep cholestyramine, colestipol and aluminum antacids 2 hours apart; check ciclosporin levels; avoid estrogens, hormonal contraceptives, some lipid-lowering drugs and drugs that can harm the liver; nitrendipine, dapsone and ciprofloxacin may work less well	Avoid cholestyramine, estrogens, hormonal contraceptives and some lipid-lowering drugs	Keep cholestyramine, colestipol and aluminum antacids 2 hours apart; check ciclosporin levels; avoid estrogens, hormonal contraceptives and some lipid-lowering drugs; ciprofloxacin, dapsone and nitrendipine may work less well
Pregnancy	Not to be used, except in absolute necessity	Contraindicated	Not to be used unless necessary; pregnancy category C
Breastfeeding	Must not be taken	Not stated	Weigh the benefits for mother and child
Children	Pediatric use not foreseen	Pediatric use not foreseen	Safety not established
Kidney disease	Not stated	Not stated	Not to be used in severe kidney failure
Driving	No effect	No grounds for an effect	No finding of an effect
Side effects listed	Pasty stools or diarrhea; occasional bowel irregularity that usually settles; rarely nausea, vomiting or liquid stools; very rarely hives; very rarely gallstone calcification (reported with UDCA)	Occasional bowel irregularity that usually settles; rarely nausea, vomiting or liquid stools; gallstone calcification reported	Rare: bowel upset that settles with continued use, nausea, vomiting, liquid stools
Overdose	Diarrhea; less is absorbed at higher doses	Rare, as the toxic dose is much higher than the therapeutic dose	Very rare, as the toxic dose is much higher than the therapeutic dose

Our translation of each label's summary of product characteristics, sections 4.2 to 4.9. “Not stated” means the label does not say.^[1,2,30,32]

On overdose, the Tudcabil label says diarrhea may occur, and that other symptoms are unlikely because less TUDCA is absorbed as the dose rises. In animal tests, the oral dose that killed half the animals (the LD50) was 4,500 mg per kg in rats and 3,000 to 3,500 mg per kg in mice.^[1,2]

Specific groups

• Older adults. No trial was designed for older people or reported side effects by age. The average age in the trials that report it was about 47 to 58,^[4,5,7,14] the 199-person liver trial took people up to 70,^[3] and several trials took no one over 65.^[12,21,29] The Turkish label says there are no reports for this group.^[2]
• Pregnancy. No study in pregnant women. Both labels list pregnancy as a contraindication. The Tudcabil label cites animal studies of other bile acids that suggest a risk to the fetus early in pregnancy; the Taurolite label reports rat and rabbit studies of TUDCA itself without that finding.^[1,2]
• Breastfeeding. No study. It is not known whether TUDCA passes into breast milk. The Tudcabil label says it must not be taken while breastfeeding; the Taurolite label says to weigh the benefits for mother and child.^[1,2]
• Children. One trial in newborns on intravenous nutrition gave 30 mg per kg a day; its summary reports no side-effect data.^[19] The labels say safety in children has not been established and that pediatric use is not foreseen.^[1,2]
• Liver disease. Many of the studies (13 of the 33) were in people with liver disease. In cirrhosis, one trial of 23 people at 750 mg a day reported no side effects.^[27] The Tudcabil label advises liver tests every 4 weeks for the first 3 months, then every 3 months, especially in advanced primary biliary cholangitis.^[1]
• Kidney disease. No study. The Taurolite label says not to use it in severe kidney failure.^[2]
• Bowel surgery or bowel disease. The labels advise avoiding it after removal of the last part of the small intestine, with an ileostomy, or with conditions such as regional ileitis that disturb how bile acids are recycled.^[1,2]

Reports from outside clinical trials

Trials record side effects in a defined group, against a comparison. The sources below do not. They are spontaneous reports to FDA, one published case report and statements in trial sponsors' documents, with no count of how many people took TUDCA, so they cannot give a rate or show cause. We set them out here as they stand.

FDA · supplement reports (CAERS)

9 reports, 2020–2026

TUDCA was the only product in 1, an allergic reaction with throat pain. In the other 8 it was one of several products, named as a suspect in 5 and as taken alongside in 3. Two led to a hospital stay: a seizure, with 11 products listed, and a liver injury in which other supplements were the suspects. One more, with a TUDCA-named product among 16, listed raised liver enzymes. No deaths.^[8]

FDA · medicine reports (FAERS)

59 reports, 2004–2026

Every one also lists other medicines, often for amyloidosis or ALS. TUDCA was named as a suspect in 4 and as taken alongside in 55, including all 5 reports of a death. A further 702 reports concern Relyvrio, the combination drug, and are left out.^[9]

Published case report · US

1 liver injury

A 55-year-old woman took the anti-parasite drug fenbendazole with TUDCA 500 mg a day for 4 weeks. The authors' causality assessment named fenbendazole as the highly probable cause.^[33]

Sponsor statement · Italy

898,000 tablets sold, 1997–2007

“There were no reported cases of toxicity related to Tudcabil capsules.” The same paragraph lists mild abdominal pain and diarrhea as common, with some cases of itching and a very limited number of raised liver enzymes. From a drug company's trial protocol, citing a product profile; it does not say how reports were collected or define toxicity.^[31]

Investigator statement · US protocol

At least 20,000 doses dispensed, 1996–2001

No reports about toxicity had arrived in this period, according to a US university's trial protocol, citing a different product profile. It names diarrhea, headache and abdominal pain as the infrequent side effects seen in human studies.^[34]

FDA's own caution: “The presence of an adverse event report in HFCS does not mean the FDA has determined that the product listed was the cause of the event.”^[10] For medicines: “Existence of a report does not establish causation.”^[35]

Counts from openFDA, searched October 17, 2026 (supplement data to July 7, 2026; medicine data to July 30, 2026), for every name of the ingredient and the brand names Tudcabil and Tauro. FDA does not remove every duplicate, and some of the 59 medicine reports appear to describe the same person. None of these sources can give a rate.

In the United States

In the US, TUDCA is sold as a dietary supplement. FDA does not approve dietary supplements before they are sold; companies are responsible for their safety and labeling, and FDA acts after products reach the market.^[36] TUDCA is not on FDA's list of new dietary ingredient notifications.^[37] As taurursodiol, it was one of the two ingredients in Relyvrio, an ALS drug approved in 2022 and withdrawn in 2025;^[38] the safety data for that combination are not TUDCA's own, and this review leaves them out.

FDA import alerts list three TUDCA products or ingredients, from 2009, 2013 and 2021. Where FDA gives a reason, it concerns labeling: one product was held because its label claimed to treat the liver, which makes it an unapproved drug.^[39,40]

What we still don't know

All 33 studies

Every study in this review, with what it reported on safety, set out on the same fields. “Not stated” means the source we could read is silent on it. On a phone, scroll the table sideways.

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Study	People	Design	Compared with	Dose	Length	Side effects	Serious events	Stopped for side effects	Safety data from
Gallbladder and bile
Croce 1993[7]	203 adults after gallbladder removal (101 on TUDCA)	Controlled trial	No treatment	500 mg/day	Checked at 1, 2 and 3 months	2 of 101 on TUDCA, 3 of 102 untreated; type not stated	Not stated	Not stated	Abstract
Gallo 1993[25]	34 people with gallstones (31 finished)	Randomized, single-blind	UDCA	10 mg/kg/day	6 months	UDCA better tolerated; no counts given	Not stated	3 of 34 did not finish; reasons not stated	Abstract
Muraca 1995[17]	33 people with radiolucent (non-calcified) gallstones	Dose-ranging study, no control group	None	3.5–16.6 mg/kg/day	4–6 weeks	Not stated	Not stated	Not stated	Abstract
Bazzoli 1995[41]	262 people on stone-dissolving bile acids, 31 on TUDCA	Observational comparison	UDCA, CDCA	Not stated	Not stated	Stones calcified in 4 of 31 on TUDCA (12.9%), 13.2% on UDCA, 8.8% on CDCA; not a significant difference	Not stated	Not stated	Abstract
Portincasa 1996[42]	People with gallstones and healthy volunteers (number not stated)	Single dose, then 1 month	UDCA; placebo (single dose)	10 mg/kg	Single dose; 1 month	Not stated	Not stated	Not stated	Abstract
Rudolph 2002[43]	8 people with blocked bile ducts from pancreatic cancer, with drains	Crossover	UDCA at an equal molar dose	1,000 mg	Short study periods	Not stated	Not stated	Not stated	Abstract
Gao 2022[44]	96 people with gallstones before surgery (48 took TUDCA)	Randomized, four groups of 24	Probiotic; TUDCA plus probiotic; no treatment	5–10 mg/kg/day	2 weeks	Not stated	Not stated	Not stated	Full text
Duan 2022[45]	70 people with gallstones (63 analyzed), all on TUDCA	Randomized trial of an acupuncture technique	Sham procedure (both groups on TUDCA)	500 mg/day	8 weeks	Not stated	Not stated	Not stated	Full text
Liver disease
Ferri 1993[24]	30 people with primary biliary cholangitis (25 finished)	Randomized	UDCA	12–15 mg/kg/day	6 months	UDCA better tolerated; no counts given	Not stated	5 of 30 did not finish; reasons not stated	Abstract
Panella 1995[46]	5 people with hepatitis C liver disease	Single group, no control	None	Printed as 10–13 mg/day (probably per kg)	3 months	Not stated	Not stated	Not stated	Abstract
Crosignani 1996[11]	24 people with primary biliary cholangitis	Randomized to three doses	Dose vs dose	500, 1,000 or 1,500 mg/day	6 months	“Diarrhea was the only side effect”; how often, and at which dose, not stated	Not stated	Not stated	Abstract
Setchell 1996[47]	People with primary biliary cholangitis (number not stated)	Randomized dose groups	Dose vs dose	500, 1,000 or 1,500 mg/day	6 months	Not stated	Not stated	Not stated	Abstract
Larghi 1997[26]	23 people with primary biliary cholangitis	Crossover (everyone took both)	UDCA	500 mg/day	6 months on each	“No patient complained of side effects”	Not stated	Not stated	Abstract
Crosignani 1998[48]	150 people with chronic hepatitis C	Randomized, placebo-controlled, several centers	Placebo	500 or 750 mg/day	6 months	Not stated	Not stated	Not stated	Abstract
Angelico 1999[28]	33 people after a liver transplant (16 on TUDCA)	Randomized pilot	No treatment	500 mg/day	12 months	“Safe and well tolerated”; no counts given	5 deaths among 29 followed long term, 3 in the TUDCA group, “none of which was related to treatment”	None (“No drop outs occurred”)	Abstract
Invernizzi 1999[49]	12 women with primary biliary cholangitis	Crossover	UDCA	750 mg/day	2 months on each	Not stated	Not stated	Not stated	Abstract
Caglieris 2000[50]	10 people with cirrhosis awaiting a transplant	Compared with earlier patients	Untreated patients from the year before	Not stated	Until transplant (under 6 months)	Not stated	Not stated	Not stated	Abstract
Heubi 2002[19]	52 newborns on intravenous nutrition after surgery (22 on TUDCA)	Controlled trial	Untreated or placebo	30 mg/kg/day	Up to 120 days	Not stated	Not stated	Not stated	Abstract
Hepatology Research 2002[51]	106 people with chronic hepatitis C on interferon (55 on TUDCA)	Randomized add-on trial	Interferon alone	10 mg/kg/day	6 months, then 6 months tapering	Not stated	Not stated	Not stated	Abstract
Pan 2013[27]	23 people with cirrhosis (18 analyzed)	Randomized, double-blind	UDCA	750 mg/day	6 months	“No patient complained of side effects”	Not stated	5 of 23 left the analysis under the inclusion criteria	Abstract
Ma 2016[3]	199 people with primary biliary cholangitis (129 on TUDCA)	Randomized, double-blind	UDCA	750 mg/day (250 mg three times a day)	24 weeks	Any side effect 44% vs 40% on UDCA (P=0.55); judged related to the medicine in 4 of 129 (diarrhea, itching, rash, period pain) vs 3 of 70	None (“No serious adverse events occurred”)	4 left each group; reasons not stated	Full text
Gut
Lamm 2025[15]	14 people with ulcerative colitis (13 assessed for safety)	Single group, open-label; preprint	None	1,750–2,000 mg/day in three doses	6 weeks	Nausea or indigestion in 6 of 13; slightly more frequent stools in 2; all mild to moderate and short-lived	None	None; 2 lowered the dose to 1,000 mg/day	Full text
Nervous system
Elia 2016[5,52]	34 people with ALS (29 analyzed, 15 on TUDCA)	Randomized, double-blind, placebo-controlled	Placebo	2,000 mg/day (1 g twice a day)	54 weeks	Judged related to the study medicine: 2 of 15 vs 3 of 14 on placebo; mild diarrhea 2 vs 2 (the registry record posts none). Blood tests, including liver tests, unchanged	None posted. Deaths: 1 on TUDCA, 3 on placebo, all from ALS	None	Full text; registry results
Zucchi 2023[16]	86 people with ALS prescribed TUDCA in Italy	Observational registry study	None for side effects	Under 1,000 mg/day in 20; 1,000 mg/day or more in 66	Average 449 days	18 of 86 (20.9%): diarrhea 12, abdominal pain 5, skin eruption 3; no difference by dose	2 needed hospital care and recovered after stopping; no deaths attributed to TUDCA (40 of 86 died or had a tracheostomy from ALS during follow-up, vs 87 of 172 matched controls)	7 of 86 (8.1%); 13 lowered the dose	Full text
TUDCA-ALS[20]	337 people with ALS (336 in the news report)	Randomized, double-blind, placebo-controlled; results not yet published	Placebo	2,000 mg/day (1 g twice a day, after a meal)	Planned for 18 months; about half reached 18 months	Top-line only: mostly mild digestive side effects in both groups	Not published	Not published	Registry record; news report
Ladakis 2025[4,23]	54 people with progressive multiple sclerosis (47 in the safety analysis)	Randomized, double-blind, placebo-controlled	Placebo	2,000 mg/day (1 g twice a day)	16 weeks	Any side effect 38% vs 33% on placebo (p=0.77); digestive 38% vs 19% (p=0.2), including diarrhea 3 of 26 vs 0 of 21	1 on TUDCA: cholangitis, hospitalized, recovered; judged unlikely related	1 on TUDCA, 0 on placebo (registry)	Full text; registry results
Metabolism
Kars 2010[14,21]	20 adults with obesity and insulin resistance	Randomized, placebo-controlled, single-blind	Placebo	1,750 mg/day with meals	4 weeks	None posted in either group; liver enzymes unchanged	None posted	None	Full text; registry results
NCT01877551[12]	27 adults with HIV and insulin resistance (13 on TUDCA)	Randomized, placebo-controlled; results posted, not published	Placebo	1,750 mg/day once a day	30 days	1 of 13 on TUDCA (influenza), 0 of 14 on placebo	None	None for side effects	Registry results
NCT02218619[13]	20 adults with new-onset type 1 diabetes (10 on TUDCA)	Randomized, placebo-controlled; results posted, not published	Placebo	1,750 mg/day	12 months	None posted in either group; no abnormal liver tests at 6, 12 or 18 months	None	None	Registry results
Healthy volunteers
Hardison 1984[18]	6 healthy men	Each bile acid for a month, then a month off	UDCA; time off treatment	20 mg/kg/day	1 month	Not stated	Not stated	Not stated	Abstract
Simoni 2013[53]	24 healthy volunteers	Test of gut transit time	Before and after loperamide	Single dose (amount not stated)	Single dose	Not stated	Not stated	Not stated	Abstract
Walsh 2016[54]	12 healthy young adults	Single dose vs placebo, crossover	Placebo	1,500 mg once	Single dose	Not stated	Not stated	Not stated	Full text
Hemingway 2020[55]	12 healthy young adults	Single dose vs placebo	Placebo	1,500 mg once	Single dose	Not stated	Not stated	Not stated	Abstract

Download the table (CSV)

Taken from each study's published summary, its full text where available, or its posted results on ClinicalTrials.gov. Searched October 17, 2026.

How we did this review

Search. On October 17, 2026 we searched PubMed and Europe PMC for every spelling of the ingredient (tauroursodeoxycholic acid, tauroursodeoxycholate, TUDCA, taurursodiol, ursodoxicoltaurine, tauro-ursodeoxycholic), combined with terms for trials, side effects, safety, pharmacokinetics, pregnancy, children, kidney and liver disease, interactions and case reports, logging 285 searches in all. We searched ClinicalTrials.gov for trials with posted results.^[56] We read the official medicine labels for Tudcabil and Tauro (Italy) and Taurolite (Turkey) in the original language, and FDA's supplement and medicine report databases through openFDA.^[8,9]

What we included. Studies in people that gave TUDCA by mouth on its own, in any condition, published as a paper or a preprint or posted as results on ClinicalTrials.gov, and one unpublished trial with a public top-line summary. We excluded studies in animals and cells, studies of UDCA alone, and combinations of TUDCA with another drug, including sodium phenylbutyrate–taurursodiol (Relyvrio, AMX0035) and doxycycline.

How we appraised them. For every study we recorded the same fields: who took part, the design, the comparison, the dose and length, the side effects in each group, serious events, and how many stopped because of side effects. We took them from the study itself, or its posted results, and wrote “not stated” where it does not say. Where a paper and its registry record differ, we report both.

How we graded the evidence. Each question gets two things: what the studies found, and a grade for how much research stands behind that finding. The grade describes the research, not the ingredient. A low grade means a finding has not yet been confirmed, not that it has been disproved.

• Strong: consistent results from several well-sized randomized, blinded trials measuring outcomes that matter to patients. No question about TUDCA has reached this level yet.
• Moderate: at least one well-sized randomized trial, with laboratory outcomes or short follow-up.
• Early: one placebo-controlled trial, or several small controlled trials.
• Preliminary: one or two studies that were small, uncontrolled or unblinded.
• Not yet studied: no published study in people.

Limits of this review. For most of the older studies we could read only the English summary, and 16 of the 33 studies report nothing on side effects in the sources we could open. We could not search Chinese-language databases or Embase, and we did not search the WHO and European report databases (VigiAccess, EudraVigilance), so reports held only there are missing.

About this review

Who wrote it. The Dr.Primal editorial team. Our editorial standards explain how we work.

Conflict of interest. Dr.Primal sells a TUDCA supplement. That is why we have kept this page free of product links and offers, reported every side effect and serious event we found, and appraised every study in the same way.

Medical review. This review has not been checked by a physician. The Dr.Primal editorial team wrote it and fact-checked every figure against its primary source. If a credentialed reviewer checks it later, we will name them here and record it in the version history.

Versions. Version 1.0, October 17, 2026: first publication. We will update this page when new studies are published, and record every change here.

Corrections. If you find an error or a study we missed, please tell us.

This review describes published research. It is not medical advice and does not replace advice from your doctor. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease.