Berberine is a bright yellow alkaloid found in several plants used in traditional medicine, including goldthread (Coptis), barberry, Phellodendron bark and goldenseal (Blais et al., Drugs 2023; Lan et al., J Ethnopharmacol 2015). Today it is sold as a purified extract: a dietary supplement in the US and, in some markets, a non-prescription drug (Blais et al., Drugs 2023). It is marketed mainly for blood sugar, cholesterol and weight.
The most important facts: berberine is not an approved drug in the US, and almost all of its clinical trials are small, short and run in China. Those trials do show modest drops in glucose, LDL cholesterol and triglycerides. Berberine is often compared with metformin, and the comparison is covered below. It also inhibits several drug-metabolizing liver enzymes in humans, which matters for anyone on prescription medicines.
This page summarizes what randomized trials, meta-analyses and the NIH report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Class | Isoquinoline (protoberberine) plant alkaloid |
| US status | Sold as a dietary supplement; not approved by FDA for any use |
| Route | Oral; products usually contain berberine hydrochloride or chloride |
| Doses used in trials | 900–1,500 mg/day in lipid trials; 500 mg three times daily in a trial against metformin |
| Oral bioavailability | 0.68% in rats; human plasma levels stay around or under 1 ng/mL |
| Half-life (human study) | Mean ≈ 31 h after a single 300 mg dose and ≈ 33 h after repeated dosing, with very wide variation |
| Main proposed mechanisms | AMPK activation (cell and rodent data); raises liver LDL-receptor levels |
| Key interaction | Inhibits CYP2D6, CYP2C9 and CYP3A4 in humans |
| WADA status | Not named on the 2026 Prohibited List |
What it is
Berberine is a quaternary ammonium alkaloid: a permanently positively charged molecule. The free cation has the formula C₂₀H₁₈NO₄⁺ and a molecular weight of 336.4 g/mol (PubChem). The chloride salt common in supplements is C₂₀H₁₈ClNO₄, 371.8 g/mol (PubChem).
Berberine-containing plants have long been used in traditional herbal medicine in Asia (Blais et al., Drugs 2023). Berberine itself has been widely used to treat gastrointestinal infections (Guo et al., Eur J Clin Pharmacol 2012). In China, berberine has more recently been used as an add-on treatment for type 2 diabetes, high cholesterol and high blood pressure (Lan et al., J Ethnopharmacol 2015).
Goldenseal, a North American herb, also contains berberine. NIH’s National Center for Complementary and Integrative Health (NCCIH) notes that very little berberine may be absorbed from goldenseal itself, so berberine trial results may not apply to goldenseal products (NCCIH, Goldenseal).
How it works
Two mechanisms are best documented, both mainly from laboratory work:
- AMPK activation. In fat and muscle cell lines, berberine activated AMPK (AMP-activated protein kinase, a cellular energy sensor) and increased glucose transporter movement to the cell surface. In diabetic mice and high-fat-fed rats it lowered body weight and improved glucose tolerance (Lee et al., Diabetes 2006). A follow-up study found berberine inhibits complex I of the mitochondrial respiratory chain in muscle cells and isolated mitochondria, similar to the effect seen with metformin, and proposed this as the route by which it activates AMPK (Turner et al., Diabetes 2008).
- LDL-receptor upregulation. In human liver cells, berberine stabilized the messenger RNA for the LDL receptor, the protein that clears LDL cholesterol from blood. In hyperlipidemic hamsters it raised liver LDL-receptor protein 2.6-fold. This works through a different pathway from statins (Kong et al., Nat Med 2004).
These are cell and animal findings. They are plausible explanations for the human trial results but have not been confirmed as the mechanism in people.
Pharmacokinetics
Berberine is poorly absorbed. In rats, absolute oral bioavailability (the share of an oral dose reaching the bloodstream) was 0.68% (Chen et al., AAPS PharmSciTech 2011). The same study found that P-glycoprotein, a pump in the gut wall, pushes absorbed berberine back into the intestine.
In a phase I study in 60 healthy Chinese adults given berberine chloride 300 mg, alone or with simvastatin or fenofibrate (Li et al., Drug Des Devel Ther 2019):
| Parameter (berberine alone) | Single 300 mg dose | Multiple doses (300 mg every 8 h for 7 days) |
|---|---|---|
| Peak plasma level (Cmax) | 0.33 ng/mL | 0.99 ng/mL |
| Time to peak | ≈ 4.0 h (wide range) | ≈ 1.7 h (wide range) |
| Terminal half-life | 30.6 ± 23.7 h | 33.4 ± 13.6 h |
Plasma levels are below 1 ng/mL even with repeated dosing, and the standard deviations are large. The long terminal half-life describes very low concentrations clearing slowly; trials still gave berberine two to three times a day.
Neither simvastatin nor fenofibrate changed berberine’s main kinetic parameters, and berberine did not change theirs in that study.
Several “enhanced absorption” forms are sold, such as dihydroberberine. In a five-person crossover pilot, 100 mg dihydroberberine gave higher plasma berberine than 500 mg standard berberine over two hours, with no difference in glucose or insulin (Moon et al., Nutrients 2021). No outcome trials have tested these forms.
Regulatory status
In the US, berberine is sold as a dietary supplement. NCCIH notes that dietary supplements are not approved by FDA before they are sold, and that manufacturers are responsible for their safety and labeling (NCCIH, Goldenseal). Berberine is not a controlled substance.
Berberine is not named on the WADA 2026 Prohibited List. The list’s metabolic-modulator class (S4.4.1) prohibits activators of AMPK and names AICAR, BAM15 and MOTS-c as examples. Berberine, which activates AMPK in laboratory studies, does not appear among the examples; metformin is in the same position. See the AICAR page for an AMPK activator that is named.
What the research shows
Most trials are from mainland China and Hong Kong, last 4–24 weeks and use 900–1,500 mg/day (Blais et al., Drugs 2023). No trial has measured hard outcomes such as heart attacks, strokes or deaths.
Type 2 diabetes
A 2022 meta-analysis pooled 37 randomized trials with 3,048 patients with type 2 diabetes, testing berberine alone or added to other glucose-lowering drugs (Xie et al., Front Pharmacol 2022):
| Outcome | Effect of berberine vs control (95% CI) |
|---|---|
| HbA1c (3-month average blood sugar) | −0.63 percentage points (−0.72 to −0.53) |
| Fasting plasma glucose | −0.82 mmol/L (−0.95 to −0.70), ≈ −15 mg/dL |
| 2-hour post-meal glucose | −1.16 mmol/L (−1.36 to −0.96) |
| Hypoglycemia | RR 0.48 (0.21 to 1.08), not significant |
The larger the baseline glucose and HbA1c, the larger the drop. Berberine did not increase total adverse events.
Head-to-head with metformin
The trial most often quoted for “berberine works like metformin” is a pilot study from Shanghai (Yin et al., Metabolism 2008). In its first part, 36 adults with newly diagnosed type 2 diabetes were randomized to berberine or metformin, each 500 mg three times daily, for 3 months. Results for the 31 who finished:
| Outcome | Metformin (n = 16) | Berberine (n = 15) |
|---|---|---|
| HbA1c, start → end | 9.15% → 7.72% | 9.47% → 7.48% |
| Fasting glucose, mmol/L | 9.96 → 7.16 | 10.63 → 6.85 |
| Triglycerides, mmol/L | 1.19 → 1.17 | 1.13 → 0.89 |
| Total cholesterol, mmol/L | 4.31 → 4.27 | 4.40 → 3.83 |
Glucose effects were similar in the two groups, and only berberine lowered triglycerides and total cholesterol. With 31 completers and 3 months of follow-up, this pilot is far too small to show the two are equivalent. A 2015 meta-analysis likewise found no significant difference between berberine and oral glucose-lowering drugs, while rating the overall quality of the included trials as limited (Lan et al., J Ethnopharmacol 2015).
How the two compare overall:
| Feature | Berberine | Metformin |
|---|---|---|
| Status | Dietary supplement | FDA-approved prescription drug for type 2 diabetes |
| Evidence base | Mostly small, short trials from China; no outcome trials | Large, long-term trials (see the metformin page) |
| Boxed warning | None (not evaluated as a drug) | Lactic acidosis (metformin label) |
| Labeled or trial dose | 900–1,500 mg/day in trials | Up to 2,550 mg/day (immediate release) per label |
| Product quality | Content often differs from label (see below) | Regulated drug manufacturing |
| Effect on lipids | Lowers LDL and triglycerides modestly | Little effect in the pilot above |
See the metformin page for its trial data, including evidence that it blunts some gains from exercise training.
Blood lipids
A 2023 meta-analysis of 18 placebo-controlled trials (n = 1,788) is the cleanest summary (Blais et al., Drugs 2023):
| Outcome | Effect vs placebo (95% CI) |
|---|---|
| LDL cholesterol | −0.46 mmol/L (−0.62 to −0.30), ≈ −18 mg/dL |
| Total cholesterol | −0.48 mmol/L (−0.63 to −0.33) |
| Triglycerides | −0.34 mmol/L (−0.46 to −0.23), ≈ −30 mg/dL |
| HDL cholesterol | +0.06 mmol/L (0.00 to 0.11) |
| Apolipoprotein B (2 trials) | −0.25 g/L (−0.40 to −0.11) |
The HDL rise was seen in women (+0.11 mmol/L) but not in men (−0.07 mmol/L, not significant). The authors describe the LDL and triglyceride reductions as small.
Metabolic syndrome and body weight
A 2025 meta-analysis of placebo-controlled trials in metabolic syndrome found berberine lowered triglycerides, fasting glucose (−0.52 mmol/L) and waist circumference (−3.3 cm). It had no significant effect on HDL or blood pressure (Liu et al., Front Pharmacol 2025).
Weight loss is one of the most heavily marketed claims. A 2026 meta-analysis of 23 randomized trials found (Elahi Vahed et al., Int J Obes 2026):
- body weight: −0.88 kg (95% CI −1.36 to −0.39);
- BMI: −0.48 kg/m² (95% CI −0.89 to −0.07);
- waist-to-hip ratio: no significant change.
That is less than 1 kg on average. The authors noted poor reporting of product purity and dose and a lack of blinding in many trials.
Polycystic ovary syndrome (PCOS)
Older reviews suggested berberine might match metformin in PCOS. A 2026 integrity-focused review found only four eligible randomized trials (n = 452) and rated all four at high risk of compromised integrity, citing absent registration, implausible recruitment timelines and possible duplicated data. It concluded that no reliable conclusions can be drawn (Perera et al., Adv Ther 2026). For another PCOS supplement in this library, see myo-inositol.
Colorectal adenoma prevention
The largest single berberine trial was a double-blind, placebo-controlled study in 1,108 people in China who had colorectal adenomas (precancerous polyps) removed (Chen et al., Lancet Gastroenterol Hepatol 2020). Berberine 0.3 g twice daily reduced adenoma recurrence over up to 2 years:
| Outcome | Berberine | Placebo |
|---|---|---|
| Recurrent adenoma | 36% (155 of 429) | 47% (216 of 462) |
| Relative risk of recurrence (95% CI) | 0.77 (0.66–0.91) | Reference |
| Constipation | 1% | under 0.5% |
No serious adverse events were reported. In an observational follow-up up to 6 years after treatment stopped, recurrence remained lower in the former berberine group (34.7% vs 52.1%) (Tan et al., Cell Rep Med 2025). These results have not been replicated outside China.
Muscle, performance and anabolic use
No controlled human trials have tested berberine on muscle mass, strength, exercise performance or body composition in trained people, or in people using anabolic steroids. Its proposed AMPK mechanism overlaps with metformin’s, and metformin blunted muscle gains from resistance training in older adults (see the metformin page). Whether berberine does the same is unknown.
Side effects and risks
Digestive effects
Gastrointestinal complaints are the most common side effect. In placebo-controlled lipid trials they occurred in 2–23% of people on berberine vs 2–15% on placebo, and no serious adverse events were reported (Blais et al., Drugs 2023). In the diabetes pilot, 34.5% of participants had transient digestive side effects, and no liver or kidney damage was seen (Yin et al., Metabolism 2008). Constipation, diarrhea and nausea are the usual complaints.
Drug interactions
Berberine acts on drug-handling enzymes in people:
- CYP enzymes. After 2 weeks of berberine 300 mg three times daily, healthy men showed reduced CYP2D6, CYP2C9 and CYP3A4 activity. The CYP2D6 marker ratio rose ninefold, and exposure to midazolam (a CYP3A4 probe) rose ≈ 40% (Guo et al., Eur J Clin Pharmacol 2012). Many common drugs use these pathways.
- Cyclosporine. In kidney transplant recipients, berberine 0.2 g three times daily raised cyclosporine blood levels; trough levels ended 29.3% higher than in patients not taking berberine (Wu et al., Eur J Clin Pharmacol 2005). Cyclosporine has a narrow safe range.
- Metformin. A goldenseal extract standardized to berberine lowered metformin exposure (AUC) by ≈ 23% in 16 healthy volunteers (Nguyen et al., Clin Pharmacol Ther 2021). NCCIH notes this drop could hinder glucose control (NCCIH, Goldenseal). This was tested with goldenseal, not purified berberine.
- Glucose-lowering drugs. In the diabetes meta-analysis, adding berberine to other drugs did not significantly raise hypoglycemia risk, but the confidence interval was wide (Xie et al., Front Pharmacol 2022).
Pregnancy, breastfeeding and newborns
In laboratory tests, berberine displaced bilirubin (a breakdown product of red blood cells) from albumin about ten times more strongly than phenylbutazone, a known displacer, and raised bilirubin levels in rats (Chan, Biol Neonate 1993). Free bilirubin can damage the newborn brain (kernicterus). NCCIH states that pregnant or breastfeeding women should not use goldenseal, that it should not be given to infants, and that its berberine constituent can be harmful to newborns (NCCIH, Goldenseal).
Long-term safety
Most trials lasted 24 weeks or less. The 2-year adenoma trial is the main longer-term safety data, and it reported no serious adverse events (Chen et al., Lancet Gastroenterol Hepatol 2020). Safety beyond that is not well studied.
Quality and contamination
Because berberine is sold as a supplement, the amount in a product is not checked before sale.
- A US study tested 15 berberine supplements. Average content was 75% of the label claim (range 33–100%), and 9 of 15 failed the 90–110% standard used for pharmaceuticals. Price did not predict quality (Funk et al., J Diet Suppl 2018).
- NCCIH notes that some goldenseal products contained other herbs or ingredients not on the label, in addition to or instead of goldenseal (NCCIH, Goldenseal).
Key takeaways
- A plant alkaloid, not an approved drug. Berberine is sold as a dietary supplement in the US and has no FDA-approved use.
- Modest metabolic effects. Meta-analyses show HbA1c falls of ≈ 0.6 points in type 2 diabetes and LDL falls of ≈ 18 mg/dL, mostly in short Chinese trials without outcome data.
- Not a proven metformin substitute. The main head-to-head trial had 31 completers and lasted 3 months; metformin has far larger and longer evidence and regulated quality.
- Weight loss is small. Pooled trials show under 1 kg of weight loss on average.
- Real drug interactions. Berberine inhibits CYP2D6, CYP2C9 and CYP3A4 in humans and raised cyclosporine levels in transplant patients.
- Avoid in pregnancy and in newborns. Berberine displaces bilirubin, and NCCIH advises against goldenseal in pregnancy, breastfeeding and infancy.
Sources
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- National Center for Complementary and Integrative Health. Goldenseal. Updated February 2025. NCCIH.
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