In short: Candibactin-AR and Candibactin-BR are two herbal supplements made by Metagenics that are usually taken together for SIBO. AR combines thyme and oregano essential oils; BR is built around berberine. They are best known from a 2014 study in which commercial herbal pairs, including this one, cleared breath tests in 46% of people after 4 weeks, compared with 34% on the antibiotic rifaximin¹. That study was a review of patient records, not a randomized trial, and both products have changed since then²³. Berberine interacts with several medicines, and neither product should be used in pregnancy²³.

This guide covers what is in each product, what the research shows, how SIBO practitioners use the pair, and who should be careful. For the wider picture of herbal treatment, see our guide to natural antimicrobials for SIBO.

What is in Candibactin-AR and Candibactin-BR?

The two products work as a pair: one is based on essential oils, the other on berberine-containing herbs. The table shows the current formulas from the labels registered in the US National Institutes of Health’s Dietary Supplement Label Database²³.

	Candibactin-AR	Candibactin-BR
Form	Softgel	Tablet
Main ingredients	Thyme oil 183 mg (55 mg thymol) and oregano oil 100 mg (55 mg carvacrol) per softgel	Berberine hydrochloride 400 mg per 2 tablets
Other ingredients	Sage leaf extract 75 mg and lemon balm leaf extract 50 mg	Oregon grape root extract 70 mg; coptis extract 30 mg; a 300 mg blend of coptis, Chinese skullcap, phellodendron, ginger, Chinese licorice and Chinese rhubarb
Label directions	1 softgel three times a day, before or with meals	2 tablets twice a day
Label warnings	Not for pregnancy or breastfeeding; stop if it causes stomach discomfort or heartburn	Not for pregnancy, breastfeeding or people taking cyclosporine; check with a practitioner if you take diabetes or other medicines

Thymol and carvacrol are the main active compounds in thyme and oregano oil; see our oregano oil guide for what is known about them. According to the manufacturer, the sage and lemon balm extracts help protect and stabilize the essential oils². Berberine is a yellow plant compound found in coptis, Oregon grape and phellodendron; see our berberine guide. Both products are sold through health practitioners².

Despite the name, there are no published studies of either product for yeast or fungal overgrowth.

What the research shows

The 2014 herbal study

Almost all the evidence for Candibactin comes from one study. In a 2014 review of the records of a US hospital gastroenterology practice, 104 adults with newly diagnosed SIBO on a lactulose breath test chose between two treatments for 4 weeks¹:

Rifaximin, 1,200 mg a day (67 people).
Herbal therapy (37 people): 2 capsules twice a day of one of two pairs of commercial products, either Candibactin-AR with Candibactin-BR, or Dysbiocide with FC-Cidal from another manufacturer.

Result	Herbal pairs	Rifaximin
Negative breath test after 4 weeks	17 of 37 (46%)	23 of 67 (34%)
As a second treatment after rifaximin failed	8 of 14 (57%)	Triple antibiotics: 6 of 10 (60%)
Side effects reported	1 case of diarrhea	1 anaphylaxis, 2 hives, 2 diarrhea, 1 C. difficile infection

The difference between herbs and rifaximin was not statistically significant, so the authors concluded that the herbs were at least as effective as rifaximin¹. In 2014, a month of the herbs cost no more than $120, compared with $1,247 retail for a month of rifaximin¹.

Limits of the evidence

The study has important weaknesses, several of which the authors point out themselves¹:

Not randomized or blinded. People chose their own treatment, so the two groups may have differed in ways that affected the results.
Small. Only 37 people took herbs, and many people who were treated did not have the follow-up breath test and were left out.
Two products pooled. The results for Candibactin and for the Dysbiocide/FC-Cidal pair were reported together, so it is not known how well Candibactin did on its own.
Old formulas. Since 2014, Candibactin-AR has changed from a capsule to a softgel, and Candibactin-BR now uses berberine hydrochloride instead of berberine sulfate and Oregon grape instead of Indian barberry¹²³.

A 2021 systematic review of alternative SIBO treatments found only two herbal studies and concluded that robust clinical trials are lacking and that the products tested were not standardized⁴.

Similar herbs in a 2024 study

A 2024 study of 179 people with SIBO at two Spanish hospitals tested a related approach: antibiotics and a low-FODMAP diet, with or without a follow-on course of an oregano-oil blend and berberine (different products from Candibactin), plus probiotics and prebiotics. The extra herbs and probiotics did not significantly change breath gas levels, but symptom remission tended to be higher, especially in methane SIBO⁵. Although the paper calls it a randomized trial, patients were grouped by the hospital that treated them.

How SIBO practitioners use Candibactin

SIBO practitioners list Candibactin-AR with Candibactin-BR, and Dysbiocide with FC-Cidal, as the combination formulas studied for SIBO. They consider them best suited to hydrogen SIBO, and note that doses may need adjusting⁶:

Methane overgrowth: they add allicin or Atrantil. See our guides to methane SIBO and allicin.
Hydrogen sulfide overgrowth: they add bismuth or a higher dose of oregano. See our hydrogen sulfide SIBO guide.
Course length: a standard herbal round is 4 weeks, sometimes 6 when gas levels are very high (70 ppm or more), followed by a repeat breath test. Most people need 2 to 5 rounds⁶.

Note that the 2014 study used 2 capsules of each product twice a day¹, while the current Candibactin-AR label recommends 1 softgel three times a day². Follow the dose your practitioner gives you.

Some people feel worse for a few days at the start of treatment, which practitioners call “die-off”; see our biofilm and die-off guide. Because SIBO often comes back, plan for relapse prevention after treatment.

Side effects and safety

In the 2014 study, only one person in the herbal group reported a side effect, which was diarrhea¹. The labels and the research on individual ingredients point to several precautions.

Who should avoid it

Pregnancy and breastfeeding. Both labels say not to use them²³. Berberine displaces bilirubin from the protein that carries it in the blood, which could harm newborns; researchers advise that berberine-rich herbs be avoided in pregnancy and by jaundiced newborns¹⁰.
Cyclosporine. In a 2005 trial in kidney transplant patients, berberine raised blood levels of this anti-rejection drug by about 29%⁸. The Candibactin-BR label says not to use it with cyclosporine³.

Drug interactions

Medicines processed by the liver. In a 2012 study in healthy men, berberine reduced the activity of three liver enzymes (CYP2D6, CYP2C9 and CYP3A4) that break down many common drugs⁷.
Diabetes medicines. Berberine lowers blood sugar; a 2022 meta-analysis of 37 trials in type 2 diabetes found it lowered HbA1c by 0.63 percentage points⁹. The label advises checking with a practitioner if you take diabetes medicines³.

Other ingredients to know about

Licorice. Candibactin-BR’s herbal blend includes Chinese licorice, but the label does not say how much³. In a 2017 meta-analysis of 18 studies, regular intake of licorice products with at least 100 mg of glycyrrhizic acid a day raised blood pressure and lowered potassium¹¹. If you have high blood pressure, heart disease or low potassium, ask your doctor.
Chinese rhubarb root. It contains anthraquinones, compounds with a laxative effect¹².
Heartburn. The Candibactin-AR label advises stopping if it causes stomach discomfort or heartburn, and swallowing the softgel whole².

If you take any prescription medicine, check with a pharmacist or doctor before starting.

Common questions

What is the difference between Candibactin-AR and Candibactin-BR?

AR is an essential-oil formula of thyme and oregano oils with sage and lemon balm. BR is a berberine formula with Oregon grape, coptis and a blend of Chinese herbs²³. In SIBO they are usually taken together, as in the 2014 study¹.

Can I take only one of them?

Neither product has been studied on its own for SIBO. The only SIBO data come from taking the two together¹.

Is Candibactin as good as rifaximin?

In the 2014 study, herbal pairs including Candibactin cleared breath tests about as often as rifaximin¹. Because the study was small, not randomized, and pooled two different products, this has not been proven. See our guide to SIBO antibiotics and our treatment comparison.

Does Candibactin work for methane SIBO?

There is no specific evidence. SIBO practitioners consider the pair best suited to hydrogen SIBO and add allicin or Atrantil for methane⁶.

Works Cited & Scientific References 12

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Candibactin-AR and Candibactin-BR for SIBO: What the Evidence Shows