Berberine Side Effects, Interactions, and Who Should Avoid It

By SciRouter Editorial Team · Last reviewed: 9 October 2026

The most common berberine side effects in trials were digestive, such as constipation, diarrhea and nausea^[1]. In a human study, berberine also slowed three liver enzymes that clear many medicines^[2]. It raised levels of the transplant drug cyclosporine^[3], can add to glucose-lowering drugs and raise the risk of low blood sugar^{[4, 5]}, and is not recommended in pregnancy or breastfeeding^{[6, 7]}.

Berberine is a plant compound found in herbs such as goldenseal and Coptis, also called huanglian^{[6, 7]}. This page is the safety companion to our guide to berberine's benefits and evidence, which covers what trials found for blood sugar, cholesterol and weight. If you take metformin or a GLP-1 drug, see our pages on berberine and metformin and berberine alongside GLP-1 drugs such as Ozempic.

What are the most common berberine side effects?

Digestive complaints were the most common side effects in berberine trials, mainly constipation, diarrhea, gas and nausea^{[1, 8, 9]}. In a 2023 pooled analysis of placebo-controlled trials they tended to be somewhat more common than with placebo, and no serious adverse events were reported^[1].

A placebo is a dummy pill, so comparing against it shows what berberine itself adds, and a meta-analysis pools results from many trials.

The 6-month BRAVO trial enrolled 337 adults with obesity and fatty liver but no diabetes^[10]. Serious adverse events occurred in 3.6% of those taking berberine 1 g a day and 1.2% of those on placebo, a difference that was not statistically significant^[10].

A risk ratio of 1.44 means digestive events were 1.44 times as common with berberine. But the 95% confidence interval, the range the data fit, included "no difference"^[11].

• Timing. In the 2008 pilot, most of those affected had digestive effects only in the first 4 weeks. Of the 14 people whose dose was cut, 10 were also taking metformin or acarbose and the rest insulin^[9].
• Dose. About one in four people (24.1%) had their dose cut to 0.3 g three times daily. In those also on other diabetes drugs, the effects cleared within a week^[9].
• A caution on BRAVO. Everyone took berberine for 30 days before randomization, and people who could not tolerate it were left out. Its side-effect numbers may look better than real-world use^[10].

Berberine interactions: which medicines are affected?

In a 2-week study of healthy men, berberine slowed three liver enzymes, CYP3A4, CYP2D6 and CYP2C9, that break down many common medicines^[2]. It also raised cyclosporine levels in kidney-transplant recipients and can add to glucose-lowering drugs^{[3, 4]}.

When these enzymes slow down, a drug they clear can build up in the blood^[2]. The table grades each interaction by evidence type. A human pharmacokinetic study measures drug levels in people. Lab and animal studies only suggest what might happen. HbA1c, used in one row, is a blood test that reflects average blood sugar over about 3 months.

Five points help when reading the table:

• Not every enzyme was affected. Test drugs for CYP2C19 (omeprazole) and CYP1A2 (caffeine) did not change significantly^[2].
• The statin study was short. It lasted 7 days, while the CYP3A4 effect was measured after 2 weeks of daily dosing^{[2, 16]}.
• Taking them at different times is not a proven fix. The enzyme changes were seen after 2 weeks of daily berberine, and the study did not test dose timing^[2].
• Interactions can also weaken a medicine. ANSES warned that berberine's ability to interact with many drugs could reduce how well some medicines work^[5]. In 16 healthy adults, a goldenseal product lowered metformin exposure by about 23%, and NCCIH notes that a drop of this size could hinder blood sugar control^{[18, 25]}.
• Goldenseal is not the same as berberine. It contains other alkaloids too^[7]. Modelling suggests most of its CYP3A effect comes from one called hydrastine, so its results do not transfer directly to berberine^[26].

Can berberine cause low blood sugar?

Yes, it can^{[5, 27]}, especially in people who take glucose-lowering medicines, because the effects can add together^{[4, 5]}. Pooled trials did not show a clear rise in low-blood-sugar events, but the data were too imprecise to rule one out^[28].

• Pooled trials. A 2022 meta-analysis of 37 trials (3,048 adults with type 2 diabetes) found no significant rise in low blood sugar. The relative risk was 0.48, but its confidence interval reached 1.08, so an increase was not excluded^[28].
• People without diabetes. In the 6-month BRAVO trial, low blood sugar occurred in 4.7% of the berberine group and 5.4% of the placebo group^[10].
• A case report. An athletic man in his 40s fainted with a blood glucose of 0.9 mmol/L (about 16 mg/dL) while taking berberine. The authors called it the first case linked to berberine and exercise, as earlier cases involved people with diabetes^[27].
• Regulators. France's ANSES listed low blood sugar and low blood pressure among the risks of berberine supplements^[5].
• GLP-1 drugs. Our searches found no published human trial testing berberine with semaglutide, tirzepatide or another GLP-1 drug^[29]. One registered trial of a multi-ingredient product containing berberine, taken with or without semaglutide (NCT07195994), was listed as recruiting in October 2026, with no results posted^[29]. Our page on berberine with or after GLP-1 drugs sets out what is known.

Can berberine affect heart rhythm?

Possibly. Three 2026 case reports described a dangerous heart rhythm, torsades de pointes, in people taking berberine, though single cases cannot prove cause^[30–32].

Lab work suggests a possible reason^[33]. hERG is a potassium channel the heart relies on to reset between beats^[33]. In lab-grown human kidney cells and frog eggs engineered to carry the human hERG channel, berberine blocked it^[33]. The time the heart takes to reset shows up on an ECG as the QT interval, but the cell study does not show how often QT changes happen in people^[33].

• A 63-year-old woman had a cardiac arrest after several months of berberine. Her ECG returned to normal after she stopped. A 2026 correction changed her age from 36 to 63^{[30, 34]}.
• A 92-year-old man developed torsades about 2 weeks after starting berberine, with a corrected QT (QTc) of 616 ms. It was 454 ms by his third day in hospital, after berberine was withheld^[31].
• A 61-year-old man taking berberine, dihydroberberine and other supplements had a QTc of 669 ms. It returned to normal after the supplements were stopped and he received hospital care that included magnesium. The case authors proposed several factors acting together: channel blockade by supplements, drug interactions that raised supplement levels, and low magnesium^[32].
• Balancing evidence. In a 2003 randomized, placebo-controlled trial of 156 adults with heart failure and frequent extra heartbeats, berberine 1.2 to 2.0 g a day was added to standard care. Outcomes were checked after 8 weeks and over a mean 24-month follow-up, and the authors reported that no drug-induced rhythm problems were observed^[35].

A 2026 review also flagged hERG blocking as an open safety question for dihydroberberine, a related form^[36]. Our comparison of berberine forms explains how they differ.

Is berberine safe during pregnancy or breastfeeding?

No. Berberine is not recommended in pregnancy or breastfeeding^{[5, 37]}, mainly because it can push bilirubin off its carrier protein, a concern for newborns^{[6, 7, 25]}.

Bilirubin is the yellow pigment behind newborn jaundice. In the blood it rides on a protein called albumin^[6]. In lab and rat studies, berberine pushed it off, so more circulated unbound^[6]. LactMed, the NIH database on medicines and breastfeeding, explains the worry: in a newborn, bilirubin can build up in the brain and cause brain damage^[7].

• The key study. In a 1993 lab study, berberine displaced bilirubin about ten times more strongly than phenylbutazone, a drug known for this effect. In adult rats given daily berberine injections for a week, unbound and total bilirubin stayed raised^[6].
• Why it was studied. Huanglian, a Chinese herb rich in berberine, had been reported to pose some risk of kernicterus, a form of bilirubin brain damage, in jaundiced newborns. The author advised avoiding high-berberine herbs in jaundiced newborns and pregnant women^[6].
• What is missing. The bilirubin evidence comes from lab and rat studies, not pregnant people^[6]. For birth defects, the research is limited to one report of 218 pregnancies exposed to huanglian, so it is not known whether berberine raises that chance^[38]. MotherToBaby, an information service run by the Organization of Teratology Information Specialists, also notes that one study suggests berberine might cause uterine contractions^[38]. Berberine can pass into breast milk, but no data show how much^{[7, 38]}.
• What agencies say. NIH's NCCIH says berberine is likely unsafe for infants and may be unsafe during pregnancy or breastfeeding, because exposure has been linked to a harmful buildup of bilirubin in infants^[37]. Its goldenseal page adds that people who are pregnant or breastfeeding should not use goldenseal^[25]. LactMed says most sources recommend avoiding newborn exposure^[7]. As of 2019, France required labels on supplements made from berberine-containing plants to warn pregnant women not to use them^[5].

Does berberine affect the liver, kidneys or hormones?

Short studies have not shown liver or kidney harm, though they were not designed to catch rare problems^{[39, 40]}. One pair of trials found that berberine moved testosterone in opposite directions in women and men^[41].

• Liver and kidneys. A 2020 meta-analysis of randomized trials found no significant effect on the liver enzymes ALT and AST^[39]. In a 30-day study of 19 healthy adults taking a micellar berberine at 1,000 mg a day, liver and kidney markers did not change significantly versus placebo. That study was linked to the formula's maker^[40].
• Hormones. In a 12-week placebo-controlled trial of 100 women in Hong Kong, berberine 500 mg twice daily lowered testosterone. In stored samples from an earlier trial of 84 men on the same dose, it raised testosterone. Results were in statistical units, so the real-world size is unclear^[41].

Who should not take berberine?

Health agencies advise against berberine for pregnant and breastfeeding people, infants and children^{[5, 25, 37]}. Anyone on prescription medicines should check with a clinician or pharmacist first^{[2, 3]}.

Health agencies advise against berberine for people who are:

• Pregnant or breastfeeding^{[5, 7, 25, 37]}.
• Newborns or infants^{[7, 25, 37]}.
• Children or teenagers, according to France's ANSES^[5].
• Living with diabetes, a liver disorder or a heart disorder (France's ANSES advised these groups to avoid berberine supplements)^[5].

Talk to a clinician or pharmacist first if you:

• Take a medicine cleared by CYP3A4, CYP2D6 or CYP2C9^[2].
• Take cyclosporine or tacrolimus. Ask the clinician who prescribes it^{[3, 15]}.
• Take medicines that lower blood sugar, including metformin^{[4, 28]}.
• Take a GLP-1 drug such as semaglutide or tirzepatide. We found no published trial of the combination^[29].
• Take blood pressure medicines. In pooled trials, adding berberine tended to lower blood pressure further^[42], and ANSES listed low blood pressure as a risk^[5].
• Have a heart-rhythm condition, a long QT interval or low magnesium^{[32, 33]}.

What should you report to a doctor?

Tell every clinician and pharmacist that you take berberine, and seek urgent care for fainting^{[27, 30]}. Also report low blood sugar readings or digestive symptoms that do not settle^{[9, 27]}.

• Your berberine use, including before procedures. In one heart-rhythm case, berberine use came to light only before a planned invasive procedure^[30].
• Fainting or blacking out. It happened in the low-blood-sugar case and in two heart-rhythm cases^{[27, 31, 32]}.
• Low readings on a home glucose meter, especially if you take glucose-lowering medicines^{[27, 28]}.
• Digestive symptoms that are severe or last beyond the first few weeks. In the 2008 pilot, most of those affected had them only in the first 4 weeks^[9].
• Yellowing of a newborn's skin or eyes after exposure to berberine in pregnancy or through breastfeeding^{[6, 7]}.

Questions to bring to your prescriber:

• Are any of my medicines cleared by CYP3A4, CYP2D6 or CYP2C9?
• If I add berberine, should I check my blood sugar more often?
• Do any of my medicines or conditions affect my QT interval?
• Would any of my drug levels need checking?

Product quality is a separate risk. Labels are not always accurate: when a university lab measured 15 berberine supplements bought from US sellers, they held between 33% and 100% of the berberine on the label, 75% on average^[43]. A 2026 review of 25 "natural GLP-1" patch and gel products, with berberine among the most-listed ingredients, found no posted certificates of analysis, the lab reports that confirm what a product contains^[44]. Our buyer's checklist for berberine supplements explains what independent testing checks.

For the benefits side, including how large the effects on blood sugar, cholesterol and weight were, see our full evidence review of berberine.

Frequently asked questions

Why are doctors cautious about berberine's side effects and interactions?

The published evidence on berberine gives doctors several reasons for caution. A 2018 review of 16 berberine trials on blood fats (2,147 participants) rated the trials as generally low in methodological quality, with a high risk of bias^[45]. In a 2-week study of healthy men, berberine slowed liver enzymes that clear many common medicines^[2]. It is not recommended in pregnancy or breastfeeding^{[5, 37]}. And three 2026 case reports linked it to a dangerous heart rhythm, without proving cause^[30–32].

Can berberine cause heart problems?

Berberine has been linked to a dangerous heart rhythm in a few case reports, but those reports cannot prove it was the cause. Three 2026 case reports described torsades de pointes in people taking berberine^[30–32]. Lab studies offer a possible reason, because berberine blocked the hERG heart channel in cells^[33]. A 2003 trial of 156 adults with heart failure did not report abnormal rhythms from berberine^[35].

What cannot be taken with berberine?

Berberine should not be combined with prescription medicines without a clinician's or pharmacist's check. In a human study it slowed CYP3A4, CYP2D6 and CYP2C9, enzymes that clear many drugs^[2]. It raised cyclosporine levels in transplant patients^[3], was linked to raised tacrolimus levels in one child^{[14, 15]}, and can add to glucose-lowering drugs^[4]. Goldenseal, a berberine-containing herb, changed blood levels of midazolam and metformin in healthy adults^[18].

Do berberine side effects go away?

In a 3-month pilot of adults with type 2 diabetes, digestive side effects from berberine 1.5 g a day were short-lived, and most of those affected had them only in the first 4 weeks^[9]. In people also on other diabetes drugs, they cleared within a week once the dose was cut to 0.3 g three times daily^[9]. That was one small study, so berberine side effects that persist are worth raising with a clinician.

Is berberine bad for your liver or kidneys?

Short trials have not shown liver or kidney harm from berberine. A 2020 meta-analysis of randomized trials found no significant effect on the liver enzymes ALT and AST^[39]. In a 30-day study of 19 healthy adults, liver and kidney markers did not change significantly versus placebo^[40]. These studies were short and small, so they cannot rule out rare problems with longer use.

Is it safe to take berberine every day long term?

The long-term safety of daily berberine is not established. Placebo-controlled lipid trials lasted 4 to 24 weeks^[1], and a 2026 trial ran 6 months with adverse events similar to placebo (serious adverse events 3.6% vs 1.2%, not significant)^[10]. France's food-safety agency ANSES concluded in 2019 that the safety of berberine supplements cannot currently be guaranteed^[5]. Anyone on other medicines should review daily berberine with a clinician^[2].

Can you take berberine while pregnant or breastfeeding?

Berberine is not recommended during pregnancy or breastfeeding. In lab and rat studies it pushed bilirubin off its carrier protein, which raises concern about bilirubin building up in a newborn's brain^{[6, 7]}. No data show how much berberine passes into breast milk^[7]. NIH's NCCIH says goldenseal, a berberine source, should not be used while pregnant or breastfeeding^[25].

References

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This content is for education only and is not medical advice. Talk to your healthcare provider before starting any supplement, especially if you are pregnant, nursing, take medication, or have a medical condition.