Last updated: September 26, 2026 · Originally published: May 14, 2026 · By Eternal Elixir Editorial
TUDCA side effects are mostly in the gut: loose stools or diarrhoea, stomach pain and nausea. In a 24-week trial of 750 mg a day, 4 of the 129 people taking TUDCA (3.1%) had a side effect the investigators linked to it, and none was serious. In a 54-week trial at 2,000 mg a day, mild diarrhoea showed up in 2 of 15 people on TUDCA and 2 of 14 on placebo. The bigger cautions sit outside the gut. Do not take TUDCA if you have a blocked bile duct or an inflamed gallbladder, keep it two hours away from bile-binding medicines and aluminium antacids, and skip it if you are pregnant, breastfeeding or under 18.
This guide to TUDCA side effects in Australia sets out what the human trials recorded, how often, at what dose and for how long, and where a 500 mg supplement capsule sits against them. It also covers the liver and kidney results, daily use, what not to take with TUDCA, and when to stop and see your GP.
Key takeaways
- Diarrhoea is the one side effect every safety study here mentions. It was the only side effect recorded in a six-month trial of 500 to 1,500 mg a day.
- Gut symptoms tend to come early. In the largest placebo-controlled trial, which paired TUDCA with a second compound, they were more common than placebo in the first three weeks and less common after that.
- Serious reactions were rare: none in a 24-week trial of 199 adults, and 2 of 86 people in a real-world study needed hospital care and recovered after stopping.
- Most trial doses were 750 to 2,000 mg a day. A 500 mg capsule matches the lowest dose tested, so the trial figures are a guide for it, not a forecast.
- Talk to your doctor first if you take any regular medicine, have a liver or gallbladder condition, or are pregnant or breastfeeding.
Eternal Elixir makes TUDCA 500mg, and it is our pick for adults who want the lowest trial dose in a single capsule: 500 mg of TUDCA per vegetarian capsule, 90 capsules to a bottle, one a day with a meal. That matches the lowest dose in the 1996 trial below and is under the 750 to 2,000 mg a day used in the others. Whether side effects are rarer at 500 mg has not been tested head to head, so we won’t claim it.
TUDCA Side Effects at a Glance
| Side effect | What the human studies recorded | When it shows up | What to do |
|---|---|---|---|
| Diarrhoea or loose stools | The only side effect at 500 to 1,500 mg a day for six months (24 adults). 14.0% of 86 people in a real-world study. 2 of 15 on TUDCA and 2 of 14 on placebo at 2,000 mg a day for 54 weeks. | Usually in the first weeks | Take it with a meal. Stop and call your GP if it is severe or lasts more than two or three days. |
| Stomach pain or discomfort | 5.8% in the real-world study. More common than placebo in the first three weeks of a trial that paired TUDCA with a second compound. | Mostly the first few weeks | Take it with food. Stop if the pain is strong, especially under the right ribs. |
| Nausea | One of the main gut complaints in the first three weeks of the paired trial. | Early on | Take it with a meal rather than on an empty stomach. |
| Itching or rash | 3 of 129 people on TUDCA (2 itching, 1 rash) in the 24-week trial. Skin eruption in 3.5% of the real-world group. | Any time | Stop and see your doctor if a rash spreads or you get hives. |
| Serious reactions | None in the 24-week trial. 2 of 86 people in the real-world study needed hospital care and recovered after stopping. | Rare | Stop taking it and get medical help. |
What Is the Most Common Side Effect of TUDCA?
Diarrhoea, or looser and more frequent stools. It is the one side effect that appears in every study in this guide that reported side effects. In a six-month trial where 24 adults took 500, 1,000 or 1,500 mg a day, diarrhoea was the only side effect the researchers reported (Crosignani et al., 1996). In a real-world study of 86 people taking TUDCA, 12 of them (14.0%) had diarrhoea, the most common side effect in that group (Zucchi et al., 2023).
TUDCA is a bile acid, and bile acids do their work in the gut. The prescribing information for UDCA (TUDCA is UDCA joined to taurine) lists soft stools or diarrhoea as a common effect and diarrhoea as the likely result of taking too much. It also notes that less UDCA is absorbed as the dose rises, so more of it passes out through the bowel.
Taking TUDCA with a meal is the simplest step. Our label says to take one capsule daily with a meal. Two Australian sellers of other brands point the same way on their product pages. Emrald Labs’ listing says some people may get nausea, stomach discomfort, diarrhoea or bloating “particularly when taken on an empty stomach”, and OHC Longevity’s says mild digestive discomfort may occur if it is taken on an empty stomach.
What the Human Trials Recorded, and at What Dose
We found no trial that tracked TUDCA side effects in healthy adults over weeks or months. The safety data come from people under specialist care, mostly for a bile duct liver condition or a serious neurological illness. Those groups are unwell, and most took more TUDCA than a supplement serve, so read these figures as what TUDCA can do at trial doses rather than a forecast for one 500 mg capsule.
| Study | Who took part | TUDCA a day | How long | Side effects recorded |
|---|---|---|---|---|
| Crosignani et al., 1996 | 24 adults with a bile duct liver condition | 500, 1,000 or 1,500 mg | Six months | Diarrhoea was the only side effect. |
| Ma et al., 2016 | 199 adults with a bile duct liver condition: 129 on TUDCA, 70 on UDCA | 750 mg (250 mg three times a day) | 24 weeks | Adverse events in 44% on TUDCA and 40% on UDCA, most judged unrelated to the capsules. 4 people on TUDCA (3.1%) had drug-related events: diarrhoea (1), itching (2), rash (1) and period pain (1). No serious adverse events. |
| Elia et al., 2016 | 34 adults with a serious neurological illness, 29 analysed: 15 on TUDCA, 14 on placebo | 2,000 mg (1,000 mg twice a day) | 54 weeks | Mild diarrhoea in 2 on TUDCA and 2 on placebo. Blood test results did not change in either group. |
| Paganoni et al., 2020 | 137 adults with a serious neurological illness: 89 on TUDCA plus sodium phenylbutyrate, 48 on placebo | 1,000 mg for three weeks, then 2,000 mg, with sodium phenylbutyrate | 24 weeks | Gut side effects in 67% on the active capsules and 60% on placebo. They were more common than placebo in the first three weeks and less common after. Diarrhoea made 6% stop, against none on placebo. |
| Zucchi et al., 2023 | 86 people with a serious neurological illness taking TUDCA in routine care | Under or over 1,000 mg | Up to and beyond 12 months | 18 people (20.9%) had side effects that led to a lower dose or stopping. Diarrhoea 14.0%, stomach pain 5.8%, skin eruption 3.5%. 7 people (8.1%) stopped, and 2 needed hospital care and recovered. |
The 24-week trial is the most useful for a supplement buyer: it was double-blind, it used a moderate 750 mg a day, and it compared TUDCA against UDCA, the prescription bile acid, in 199 adults (Ma et al., 2016). The 54-week trial is the longest against placebo, at 2,000 mg a day (Elia et al., 2016).
The trial by Paganoni and colleagues is the largest placebo-controlled one, but its capsules also held sodium phenylbutyrate, so its gut side effects cannot be pinned on TUDCA alone. The researchers noted that diarrhoea, nausea and abdominal discomfort are known effects of TUDCA. Their weight results were similar in both groups (Paganoni et al., 2020).
Where a 500 mg capsule sits
Our capsule holds 500 mg, the lowest dose in the 1996 trial. That is two-thirds of the 750 mg in the 24-week trial and a quarter of the 2,000 mg in the two neurological trials. In the real-world study, the researchers found no difference in side effects between people on less than 1,000 mg a day and those on more. So we can’t promise fewer side effects at 500 mg. It is the smallest amount anyone has tested over months.
What has not been shown:
- No trial has recorded side effects of 500 mg a day in healthy adults.
- No placebo-controlled trial of TUDCA has run longer than 54 weeks.
- We found no TUDCA safety data in pregnancy, breastfeeding or children.
Is TUDCA Hard on the Liver or Kidneys?
Not in the trials we found, though the data are limited. Liver blood tests did not worsen on TUDCA in any of the three trials that reported them (the 1996, 24-week and 54-week trials). The prescribing information for UDCA asks for liver blood tests under medical supervision in people taking it for a liver condition, which is one reason anyone with a diagnosed liver condition should only use TUDCA with their doctor.
None of the studies in this guide reported kidney harm. In the 54-week trial at 2,000 mg a day, laboratory results did not change. In the paired trial, kidney and urinary events were less common on the active capsules (11%) than on placebo (17%). People with reduced kidney function were not the focus of any trial, so if you have kidney disease, talk to your doctor before taking TUDCA.
Is It Okay to Take TUDCA Every Day?
Every trial in this guide gave TUDCA daily, for 24 to 54 weeks, and some people in the real-world study took it for more than a year. Our label directs one capsule a day. We found no evidence that you need to cycle TUDCA for safety. Daily use for a few months matches how it was tested, at higher doses than ours. For use over years the data are thin, so if you plan to stay on it, review it with your GP every few months.
For timing, meals and how long to take it, see our TUDCA dosage guide for Australia.
Who Should Avoid TUDCA or Check With a Doctor First
- A blocked bile duct, an inflamed gallbladder or frequent gallstone pain. The prescribing information for UDCA, TUDCA’s close relative, says not to use it in these situations. Do not take TUDCA if any of these apply unless your specialist advises it.
- A diagnosed liver condition. Most TUDCA trials were in people with one, but they were under specialist care with regular blood tests. Talk to your doctor rather than choosing a dose yourself.
- Pregnancy and breastfeeding. We found no TUDCA safety data for either. The UDCA prescribing information says it must not be used in pregnancy unless clearly necessary. Do not take TUDCA while pregnant or breastfeeding unless your doctor recommends it.
- Under 18. The trials were in adults, and three of the other TUDCA listings in our table say they are not for anyone under 18.
- An allergy to bile acids. The UDCA prescribing information lists hypersensitivity to bile acids as a reason not to use it.
- Regular prescription medicines. See the next section, and check with your pharmacist or GP before you start.
What to Avoid When Taking TUDCA
We found no interaction study of TUDCA itself, so the closest guide is the prescribing information for UDCA. Taking TUDCA raises the UDCA in your bile: after six months on TUDCA, UDCA made up 15% to 48% of the bile acids in participants’ bile (Crosignani et al., 1996). The UDCA cautions are a sensible starting point.
- Cholestyramine or colestipol. These medicines bind bile acids in the gut and block their absorption. The UDCA guidance is to take them at least 2 hours before or after.
- Antacids containing aluminium hydroxide or smectite. Same problem, same 2-hour gap.
- Ciclosporin. UDCA can change how much ciclosporin is absorbed, so doctors check blood levels. Tell your prescriber before adding TUDCA.
- Ciprofloxacin, nitrendipine and dapsone. UDCA reduced the absorption or effect of each in isolated reports or small studies. Ask your pharmacist.
- Statins. In healthy volunteers, UDCA 500 mg a day with rosuvastatin 20 mg a day slightly raised rosuvastatin levels. How much this matters, and whether it applies to other statins, is unknown, so mention TUDCA to your GP.
- Glucose-lowering medicines. In a four-week trial of 20 adults with a high BMI, liver and muscle insulin sensitivity rose by about 30% on 1,750 mg of TUDCA a day and did not change on placebo (Kars et al., 2010). No study has tested TUDCA alongside glucose-lowering medicines, so talk to your doctor first if you take one.
- A second TUDCA product. Our Metabolic Wellness Stack already contains a bottle of TUDCA 500mg. If you take the stack, do not add a separate TUDCA bottle.
- Alcohol. We found no study of TUDCA and alcohol together, so we cannot tell you how they interact.
How to Lower Your Chance of TUDCA Side Effects
- Take it with a meal. That is what our label says, and two other sellers’ listings warn about gut symptoms on an empty stomach.
- Stay at the label dose. One 500 mg capsule a day is the lowest dose tested in the trials. Diarrhoea is the effect the UDCA prescribing information links to taking too much, so more capsules is not the answer if you feel nothing.
- Give the first three weeks a fair hearing. In the paired trial, gut side effects were more common than placebo only in the first three weeks. Mild symptoms may settle. Strong ones are a reason to stop.
- Keep it apart from bile binders and antacids. Leave at least two hours between them.
- Don’t double up. Check your other products for TUDCA, including stacks.
- Tell your GP or pharmacist if you take any regular medicines.
When to Stop TUDCA and See a Doctor
Most gut side effects in the trials were mild. Stop taking TUDCA and see your GP promptly if you notice any of these:
- diarrhoea that is severe or lasts more than two or three days
- strong pain in the upper right of your abdomen (the UDCA prescribing information lists this as a very rare effect)
- yellowing of the skin or the whites of the eyes
- dark urine or very pale stools
- a spreading rash, hives, or itching that won’t settle
- swelling of the face or lips, or trouble breathing (call 000)
These are warning signs for the liver and bile system in general. They were not common in the TUDCA trials, but they need a proper check.
TUDCA vs Other Liver Supplements: Is the Side Effect Profile Better?
We found no trial that compared the side effects of TUDCA with those of other liver supplements head to head, apart from the prescription bile acid UDCA. In the 24-week trial, adverse event rates were similar (44% on TUDCA, 40% on UDCA), and itching rose on UDCA (from 1.43% to 10.00% of people) but not on TUDCA. Our guide to the chemical differences between TUDCA and UDCA explains how the two relate.
- NAC. We set the two side by side in our TUDCA vs NAC comparison for liver support.
- Milk thistle. See how TUDCA and milk thistle compare, or our three-way look at TUDCA, NAC and milk thistle.
- Berberine. Its gut side effects and medicine interactions are in our berberine side effects guide.
- Glutathione. Our glutathione side effects guide covers its evidence. If you want it alongside TUDCA, our Reduced L-Glutathione 2000mg is taken as two capsules on an empty stomach (2,000 mg per serve), so it sits at a different time of day from a TUDCA capsule taken with a meal. We found no trial of the two together.
Choosing a TUDCA That Is Easier on Your Stomach (as of Sep 2026)
If TUDCA suits you, the label details that matter for side effects are the dose per capsule, whether the directions say to take it with food, and the capsule itself. We took each price, pack and direction from the seller’s own page in September 2026. For a wider field, see our comparison of the best TUDCA supplements in Australia.
| Product | Price (AUD, as of Sep 2026) | Pack | Label directions | Capsule | Cost per 500 mg | Buy |
|---|---|---|---|---|---|---|
| Eternal Elixir TUDCA 500mg (our pick) | $59.99 | 90 capsules of 500 mg | 1 capsule daily with a meal | Vegetarian | $0.67 | View product |
| OHC Longevity TUDCA | $89.99 | 60 capsules of 500 mg | 1 capsule daily, with or without food | Vegan (HPMC) | $1.50 | OHC Longevity |
| Nutricost TUDCA 500mg (iHerb AU) | $48.99 | 30 capsules of 500 mg | 1 capsule daily with water | Gelatine | $1.63 | iHerb AU |
| Emrald Labs TUDCA (Elite Supps) | $49.90 | 60 capsules of 250 mg | 1 capsule daily with water | Vegetarian (HPMC) | $1.66 | Elite Supps |
| Zombie Labs TUDCA (Nutrition Warehouse) | $59.95 | 60 capsules of 250 mg | 1 capsule daily with food | Vegetable cellulose | $2.00 | Nutrition Warehouse |
Who each one suits, and who it doesn’t
- Eternal Elixir TUDCA 500mg (our pick). Suits adults who want one 500 mg capsule a day with a meal, a vegetarian capsule, three months per bottle and the lowest cost per 500 mg here. It doesn’t suit someone who wants to start below 500 mg, because each capsule is a full 500 mg, or someone who wants to pick up a bottle in a shop today.
- OHC Longevity TUDCA. Suits people who want the same 500 mg dose in a vegan capsule from a seller that publishes a certificate of analysis. It costs more than twice as much per 500 mg as ours.
- Nutricost TUDCA 500mg. Suits someone who wants the lowest upfront price for a first try. The capsule is gelatine, so it doesn’t suit vegetarians, and 30 capsules last a month.
- Emrald Labs TUDCA. Suits people who want a smaller 250 mg daily amount, and its listing is plain about gut symptoms on an empty stomach. Reaching 500 mg takes two capsules, at $1.66 per 500 mg.
- Zombie Labs TUDCA. Suits people who want 250 mg with food from a sports-nutrition chain. It has the highest cost per 500 mg in the table.
If you were hoping to buy TUDCA at a pharmacy, our guide to TUDCA at Chemist Warehouse covers what is on the shelf, and our guide to whether TUDCA is legal in Australia and where to buy it covers the rest.
Eternal Elixir TUDCA 500mg: What Is in the Bottle
Each bottle of Eternal Elixir TUDCA 500mg holds 90 vegetarian capsules with 500 mg of TUDCA in each, 45 g of TUDCA in total. The label directs one capsule a day with a meal, so a bottle lasts 90 days at $59.99, or $0.67 a day. Two bottles save 10% ($107.98), three save 15% ($152.97) and five save 20% ($239.96). Orders over $100 ship free, and orders leave Sydney within 24 hours.
Who it suits: adults who have read the cautions above and want the lowest dose tested in the trials, taken once a day with food. Who it doesn’t suit: anyone pregnant, breastfeeding or under 18, anyone with a blocked bile duct or an inflamed gallbladder, and anyone on the medicines listed above without their doctor’s go-ahead.
Eternal Elixir makes this product, which is why it is our pick. The competitor details above are as their own pages state them.
Add TUDCA 500mg to cart · $59.99
TUDCA Side Effects: Frequently Asked Questions
Are there side effects of TUDCA?
Yes, mostly mild gut effects. Diarrhoea or loose stools is the most common, and stomach pain, nausea, itching and rash have also been recorded. In a 24-week trial of 750 mg a day, 3.1% of people on TUDCA had a side effect linked to it, and none was serious.
What should you avoid when taking TUDCA?
Keep bile-binding medicines such as cholestyramine and colestipol, and aluminium antacids, at least two hours away from TUDCA. Talk to your doctor first if you take ciclosporin, a statin, a glucose-lowering medicine or any other regular medicine. Avoid TUDCA if you have a blocked bile duct or an inflamed gallbladder, if you are pregnant or breastfeeding, and if you are under 18. Don’t take two TUDCA products at once.
Is it okay to take TUDCA every day?
Yes, at the label dose. Every trial in this guide gave it daily for 24 to 54 weeks. Our label directs one 500 mg capsule a day with a meal. For use beyond a year the data are thin, so review it with your GP.
Add TUDCA 500mg to cart · $59.99
Is TUDCA hard on the kidneys?
None of the studies in this guide reported kidney harm, and in the 54-week trial at 2,000 mg a day, laboratory results did not change. People with reduced kidney function have not been studied, so if you have kidney disease, ask your doctor first.
Is TUDCA safe to take long-term?
The longest placebo-controlled trial ran 54 weeks at 2,000 mg a day, four times our serve, and mild diarrhoea was no more common than on placebo. Some people in a real-world study took it for more than a year. Use over several years at supplement doses has not been tested directly.
Does TUDCA cause weight gain or weight loss?
Not in the trial that reported it. In the 24-week trial that paired TUDCA with sodium phenylbutyrate, weight changes were similar on the active capsules and on placebo. TUDCA is not a weight-loss supplement.
Can I take TUDCA with alcohol?
We found no study of the two together, so we can’t tell you how they interact. If you drink regularly and are thinking about TUDCA for liver support, talk to your GP.
How long do TUDCA side effects last?
In the paired trial, gut side effects were more common than placebo in the first three weeks and less common after that. In the real-world study, side effects went away once people stopped TUDCA. If symptoms are severe or last more than two or three days, stop and see your GP.
Where can I buy TUDCA in Australia?
Mostly online, from supplement brands and sports-nutrition retailers. Eternal Elixir ships TUDCA 500mg from Sydney within 24 hours, and the table above lists four other options with prices as of Sep 2026.
What is the best TUDCA for a sensitive stomach?
Our pick is Eternal Elixir TUDCA 500mg: one 500 mg vegetarian capsule a day with a meal, the lowest dose tested in the trials, at $0.67 a day. If you want to start lower, Emrald Labs and Zombie Labs sell 250 mg capsules. Whatever you choose, take it with food and keep to the label dose.
Add TUDCA 500mg to cart · $59.99
The Bottom Line
In human trials at 500 to 2,000 mg a day, TUDCA’s side effects were mostly gut symptoms, led by diarrhoea, and mostly mild. The cautions that matter most are a blocked bile duct or an inflamed gallbladder, bile-binding medicines and aluminium antacids, pregnancy, breastfeeding and anyone under 18. If you take a regular medicine, check with your GP first. If TUDCA suits you, start at one 500 mg capsule with a meal and give it a few weeks.
For more on what TUDCA does, read what the research shows on TUDCA’s benefits or our look at TUDCA for training and recovery, or browse the full Eternal Elixir range.
Sources
- Crosignani A, Battezzati PM, Setchell KD, et al. Tauroursodeoxycholic acid for treatment of primary biliary cirrhosis. A dose-response study. Dig Dis Sci. 1996;41(4):809-815. PubMed 8674405
- Ma H, Zeng M, Han Y, et al. A multicenter, randomized, double-blind trial comparing the efficacy and safety of TUDCA and UDCA in Chinese patients with primary biliary cholangitis. Medicine (Baltimore). 2016;95(47):e5391. PubMed 27893675
- Elia AE, Lalli S, Monsurrò MR, et al. Tauroursodeoxycholic acid in the treatment of patients with amyotrophic lateral sclerosis. Eur J Neurol. 2016;23(1):45-52. PubMed 25664595
- Paganoni S, Macklin EA, Hendrix S, et al. Trial of sodium phenylbutyrate-taurursodiol for amyotrophic lateral sclerosis. N Engl J Med. 2020;383(10):919-930. PubMed 32877582
- Zucchi E, Musazzi UM, Fedele G, et al. Effect of tauroursodeoxycholic acid on survival and safety in amyotrophic lateral sclerosis: a retrospective population-based cohort study. EClinicalMedicine. 2023;65:102256. PubMed 37842553
- Kars M, Yang L, Gregor MF, et al. Tauroursodeoxycholic acid may improve liver and muscle but not adipose tissue insulin sensitivity in obese men and women. Diabetes. 2010;59(8):1899-1905. PubMed 20522594
- Ursofalk 250mg hard capsules (ursodeoxycholic acid): summary of product characteristics. Electronic medicines compendium. medicines.org.uk
