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Barberry Supplements: What the Trials Show for Blood Sugar, Cholesterol and Blood Pressure

Barberry, a shrub whose fruit, juice and root are sold as supplements, has modest evidence at best. In small trials, nearly all from Iran, it lowered LDL cholesterol and triglycerides a little (grade B), while its effects on fasting blood sugar, HbA1c, blood pressure and weight were small or inconsistent (grade C). Its berberine can raise levels of some medicines, including cyclosporine, and barberry is not for anyone pregnant or breastfeeding, or for newborns.

Published How we grade evidenceEditorial policy

Barberry is a thorny shrub. Most trials used common barberry (Berberis vulgaris) or purple-black barberry (Berberis integerrima, sold as black barberry) as fruit extract, dried fruit, juice or root extract. Almost all are small, short and from Iran (Zhang 2025; Hussain 2024).

The short version

  • Cholesterol: LDL about 11 to 17 mg/dL lower and triglycerides about 19 to 29 mg/dL lower in three reviews of small trials of extracts, dried fruit and juice, nearly all from Iran, in adults with diabetes, metabolic syndrome, fatty liver or heart risk factors. Grade B (Hadi 2019; Zhang 2025; Musazadeh 2025).
  • Fasting blood sugar: about 15 mg/dL lower in three of four reviews of small Iranian trials, mostly in type 2 diabetes, at low certainty. Grade C (Hussain 2024; Musazadeh 2025; Zhang 2025; Safari 2020).
  • HbA1c, the 3-month sugar average: not significantly lower in three of four reviews and borderline in the fourth; an umbrella review rated it very low certainty. Grade C (Hussain 2024; Musazadeh 2025; Zhang 2025; Li 2025).
  • Blood pressure and weight: inconsistent between reviews of small Iranian trials. Grade C for each (Atefi 2021; Musazadeh 2025; Zhang 2025; Hussain 2024).
  • Safety: its berberine, in pill trials, slowed three drug-clearing liver enzymes and raised levels of the transplant drug cyclosporine; avoid barberry in pregnancy, while breastfeeding and in newborns. Grade C for the drug effects (Guo 2012; Wu 2005; Chan 1993).
Question (who, compared with what)What trials foundSize of effectGrade
LDL, triglycerides (adults with diabetes, fatty liver or heart risk factors; vs placebo, usual care, nothing or metformin)LowerLDL 11 to 17 mg/dL; triglycerides 19 to 29B
Fasting sugar (mostly type 2 diabetes; vs placebo, usual care or metformin)Lower in 3 of 4 reviewsAbout 15 mg/dLC
HbA1c (type 2 diabetes)No clear changeNot significant in 3 of 4 reviewsC
Blood pressure, weight (mixed groups)MixedSmall or inconsistentC
Liver enzymes (fatty liver, vs placebo)Lower2 small trialsC

Barberry vs berberine: what's the difference?

Berberine is one compound in barberry. In an analysis of purple-black barberry, the root held about 209 times more berberine than the fruit, most of it in the root bark, while the fruit was richer in anthocyanins, the red-purple pigments (Zhaleh 2025). One extract in a diabetes trial supplied about 157 mg of berberine in its 1 g daily dose (Hussain 2024). So juice and root-bark extract differ a lot. Berberine pill results, graded in our berberine guide, don't transfer to barberry, but berberine's effects on drug-clearing enzymes concern both (Bathaei 2025).

Does barberry lower cholesterol?

Grade B: modest drops in small trials, nearly all from Iran. A 2019 review of 5 randomized trials (339 adults), one of them a juice trial with no placebo, found total cholesterol about 24 mg/dL, triglycerides about 29 mg/dL and LDL about 14 mg/dL lower, with no significant HDL change (Hadi 2019). A 2025 review of 11 trials (718 adults, all in Iran) found LDL about 11 mg/dL and triglycerides about 24 mg/dL lower in 8 trials (386 people). It rated this high certainty, but results differed a lot between trials, its 2 metabolic syndrome trials showed no lipid change, and it mixed capsules, dried fruit and juice, some juice trials without a placebo; one study was not randomised and one trial appears twice (Zhang 2025). In type 2 diabetes, LDL was about 17 mg/dL lower in 4 trials (188 people) at moderate certainty, with no HDL change; 2 of the 4 used a placebo, one no treatment and one metformin (Musazadeh 2025).

In 31 adults with type 2 diabetes, 3 months of fruit extract lowered triglycerides, total cholesterol and LDL more than placebo, but not HDL or HbA1c (Shidfar 2012). In 84 adults on blood pressure medicines with other heart risk factors, 10 g a day of dried purple-black barberry for 8 weeks lowered triglycerides, total cholesterol, LDL and CRP (an inflammation marker) against placebo; 2 of the 42 on barberry dropped out with mild diarrhea (Emamat 2022a). That matches the B on our black barberry page; it is no stand-in for a statin (cholesterol guide).

Does barberry lower blood sugar?

Grade C: fasting sugar fell a little in most reviews, at low certainty; HbA1c showed no clear change. Most trials were in adults with type 2 diabetes, often on diabetes pills (Musazadeh 2025).

  • Fasting sugar: about 15 mg/dL lower across 8 trials (467 adults with type 2 diabetes, all in Iran), one of them against metformin and one using berberine from barberry root, in a 2024 review (Hussain 2024). A 2025 review found a similar drop in 7 trials (371 people), at low certainty; its 8 trials compared barberry with placebo in 3, usual care or nothing in 4 and metformin in 1, and the placebo subgroups showed about 24 mg/dL (Musazadeh 2025). A 2020 review of adults, not all with diabetes, found no significant change (Safari 2020).
  • HbA1c: in the 2024 review, a 0.54-point drop across 6 trials (313 people) was not significant until one juice trial was left out (Hussain 2024). The 2025 diabetes review's 0.65-point drop sat at the edge of significance, with none in its 2 placebo-controlled trials (Musazadeh 2025); two other reviews found no significant change (Zhang 2025; Safari 2020), and an umbrella review rated the evidence very low certainty (Li 2025).
  • Against metformin: in 80 adults (60 analysed), 3 months of purple-black barberry root extract or metformin left HbA1c at 7.5% and 7.2%, not a significant difference, so the trial can't say whether barberry is better or worse; a drug company part-funded it (Sanjari 2020).

Our black barberry page shows grade B for fasting sugar and HbA1c; this guide gives C because the reviews that rated certainty called it low or very low, and HbA1c was not significant in three of four reviews. See the blood sugar guide.

Does barberry lower blood pressure?

Grade C, mixed. A 2021 review of 5 trials (350 adults, 4 to 12 weeks) and the 2025 diabetes review both found no significant blood pressure change (Atefi 2021; Musazadeh 2025). The 2025 mixed-groups review found systolic about 10 mmHg and diastolic about 11 mmHg lower, from only 3 trials and at low certainty (Zhang 2025). In 84 adults who stayed on blood pressure medicines, 2 months of dried purple-black barberry lowered 24-hour systolic pressure more than placebo (Emamat 2022b), so its effect can add to theirs. That fits the mixed C on our black barberry page.

Does barberry help you lose weight?

Grade C: small and inconsistent. Weight was about 1.5 kg lower in 4 trials (252 people), with no significant change in BMI (Zhang 2025), and about 2.3 kg lower in 5 diabetes trials, only 2 of them placebo-controlled (Musazadeh 2025), but a 2024 review found no significant change in weight or BMI (Hussain 2024). In 106 adults with schizophrenia on antipsychotics, 3 months of root capsules did not stop weight, sugar and blood fats rising: among the 88 who finished, weight, waist size, triglycerides and blood sugar rose within the barberry group, and the barberry group gained more weight than the placebo group (about 4.6 kg against 1 kg; it also started heavier) (Rostami 2023). See the weight-loss guide.

Does barberry help fatty liver, arthritis or acne?

  • Fatty liver: grade C for lower liver enzymes. In 80 adults, 3 months of extract capsules lowered ALT from 49 to about 27 U/L, more than placebo (Iloon Kashkooli 2015); in 42 adults, 2 months of fruit extract lowered liver enzymes, blood fats and fasting sugar more than placebo (Afsharinasab 2020). These are blood markers, not liver outcomes (fatty liver disease; liver guide).
  • Rheumatoid arthritis: grade C. In 62 adults, 3 months of extract capsules lowered body fat, hip size and fasting sugar more than placebo, but HDL ("good" cholesterol) fell too; joint symptoms weren't measured (Aryaeian 2020).
  • Acne: grade D. In 49 teenagers with moderate to severe acne, a dried-fruit extract by mouth cut lesion counts about 44% from the start over 4 weeks, while placebo's change was not significant; the study did not compare the groups directly, and under-18s should take it only with their doctor (Fouladi 2012).

Which form did trials use, and how much?

In the 2025 review's trials, fruit products ran from 75 mg to 10 g a day and juice from 200 to 480 mL a day, for 3 to 12 weeks (Zhang 2025). No upper limit has been set for barberry; at these amounts, trials reported mild stomach and bowel upset. At 10 g of dried barberry a day, 2 of 42 people stopped with mild diarrhea (Emamat 2022a); on a 1 g extract syrup, one person stopped for heartburn and one for weakness (Soltani 2021); on extract capsules, 3 had diarrhea and 1 constipation in the first week (Iloon Kashkooli 2015). One juice trial's drink had 5% added sugar (Li 2025). Check the species and plant part: root and bark carry far more berberine than fruit (Zhaleh 2025).

What we'd skip

  • Barberry instead of diabetes, cholesterol or blood pressure medicine. The trials were short, small and from one country (Zhang 2025), and an umbrella review says herbal medicines belong only as an add-on to standard diabetes care (Li 2025).
  • Reviews that pool barberry with berberine pills, or with Indian barberry and milk thistle mixtures. They can't show what barberry alone does, and their reference lists include a retracted trial or trials from a research group this site doesn't use for grades (Amini 2020; Vahedi-Mazdabadi 2023; Roshanravan 2023).

Safety and interactions

  • Side effects: beyond the mild stomach upset above, an umbrella review says barberry's safety can't be determined from the available evidence (Li 2025).
  • Medicines cleared by liver enzymes: in healthy men, two weeks of berberine pills (300 mg, three times daily) slowed CYP2D6, CYP2C9 and CYP3A4, raising levels of the test sedative midazolam by 40% (Guo 2012); a 2025 review of barberry and berberine names CYP2D6 and CYP3A4 as the effects that matter most (Bathaei 2025). The FDA lists simvastatin, lovastatin, atorvastatin, warfarin, tacrolimus, sirolimus, glimepiride, metoprolol, quetiapine and sildenafil among drugs these enzymes clear (FDA); on any of them, ask your pharmacist first.
  • Cyclosporine: in kidney transplant patients, berberine pills left cyclosporine trough levels 29% higher than without them (Wu 2005); combine only if your transplant team agrees.
  • Diabetes medicines: the umbrella review advises watching closely for low blood sugar when herbs are taken with diabetes drugs, as herb-drug data are lacking (Li 2025). On insulin or a sulfonylurea, check your sugar more often and ask your prescriber; see can I take berberine with metformin?
  • Blood pressure medicines: barberry lowered systolic pressure further in people taking them (Emamat 2022b); tell your prescriber if you feel faint (blood pressure guide).
  • Heart rhythm: berberine dripped into a vein triggered torsade de pointes, a dangerous fast rhythm, in 4 of 12 people with severe heart failure (Rad 2017). That was a drip, not barberry by mouth, but with a heart-rhythm problem, ask your cardiologist first.
  • Liver: LiverTox, the US liver-injury database, names barberry as a berberine source and links berberine to neither liver enzyme rises nor clinically apparent liver injury (LiverTox). A 2026 review of 145 studies across 38 Berberis species reported liver, kidney, heart, immune and embryo harm at some doses (Ma 2026); a 2017 toxicity review notes much of this comes from animal and lab studies (Rad 2017). If your eyes or skin turn yellow or your urine darkens, stop it and get checked.
  • G6PD deficiency (an inherited enzyme shortage): berberine may cause jaundice and red-cell breakdown, and has been reported to cause kernicterus, brain damage from jaundice, in affected newborns (Rad 2017). Ask a clinician first.
  • Pregnancy: don't use it. In test-tube and rat work, berberine pushed bilirubin, the jaundice pigment, off its carrier protein, and the author advises avoiding berberine-rich herbs in pregnancy and in jaundiced newborns (Chan 1993); NCCIH says goldenseal's berberine can harm newborns (NCCIH). In an Iranian study comparing 150 children with birth defects and 150 without, eating barberry daily during pregnancy went with much higher odds of a birth defect; such studies can't prove cause (Najafi 2025). For blood sugar or blood pressure in pregnancy, ask your midwife or obstetric team.
  • Breastfeeding? Don't take it: for goldenseal, another berberine herb, there are no data on what reaches milk, and most sources say to keep newborns away from it (LactMed: Goldenseal). Ask your midwife, doctor or a lactation specialist, who can check what passes into breast milk.
  • Children: never give it to a newborn or baby; for older children, ask your child's doctor.

When to see a doctor

  • Emergency (911) for very low blood sugar that sugar doesn't fix (confusion, fainting, a seizure), fainting with a racing heart, or yellow skin or eyes in a newborn whose parent took barberry.
  • Same day for shaking or sweating with low sugar readings, feeling faint on blood pressure medicines, or new side effects after adding barberry to a medicine above.
  • Soon for yellow eyes or skin or dark urine (stop barberry first), diarrhea or heartburn lasting more than a few days, or readings that stay high.

Don't stop a prescribed medicine on your own; ask the prescriber or pharmacist. Pregnant or breastfeeding? Don't take barberry. Under 18? Check with a clinician first.

FAQ

Is barberry the same as berberine? No. Berberine is one compound in barberry, with about 209 times more in the root than the fruit in one analysis, so berberine pill results don't transfer.

Does barberry lower blood sugar? In three of four reviews of small Iranian trials, mostly in adults with type 2 diabetes, fasting sugar fell about 15 mg/dL at low certainty (grade C); HbA1c showed no clear change (grade C).

Does barberry lower cholesterol? A little: in three reviews of small trials, nearly all from Iran, in adults with diabetes, fatty liver or heart risk factors, LDL fell about 11 to 17 mg/dL and triglycerides about 19 to 29 mg/dL (grade B).

Can I take barberry with metformin? Ask your prescriber first. Sugar-lowering effects can add up, so check your sugar more often, especially on insulin or a sulfonylurea.

What are the side effects of barberry? Trials reported mild diarrhea, constipation and heartburn. Its berberine can raise levels of some medicines, including cyclosporine, and barberry is not for anyone pregnant or breastfeeding, or for newborns.

Sources

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