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Can I take berberine with metformin?

Only with your prescriber's OK, because both lower blood sugar. Adding berberine to diabetes pills such as metformin is documented in drug-level studies: in small trials, blood sugar fell further than with the pills alone. Low blood sugar on berberine has been reported in people with diabetes. No study has measured metformin levels with berberine, and it slows liver enzymes that clear other medicines. Tell your prescriber before you start it.

How well documented: Documented in drug-level studies. Studies in people measured the effect directly: the medicine’s blood levels or its effect, or a test result.

Last reviewed

How we grade evidenceEditorial policy

What's known

  • Drug-level studies: blood sugar. In small trials, adding berberine to a diabetes pill such as metformin gave better blood sugar control than the pill alone. The trials were of low quality and all ran in mainland China. In a 2024 review, berberine combined with glucose-lowering drugs lowered HbA1c (average blood sugar over about 3 months) by a further 0.69 points. (Dong 2012, Wang 2024)
  • Low blood sugar. Metformin and berberine both lower blood sugar, so their effects can add up. A 2022 review found no clear rise in low blood sugar in trials of berberine alone or with diabetes pills, but lows do happen. The authors of a 2025 case report write that "berberine-induced hypoglycaemia has previously only been reported in patients with diabetes mellitus". Their patient, a fit man in his 40s without diabetes, fainted with a blood sugar of 0.9 mmol/L, and they call new, unexplained low blood sugar "a potentially life-threatening scenario". (Xie 2022, Henshall 2025)
  • Metformin levels: not measured. No study in people has measured metformin levels with berberine itself. In rats, berberine raised metformin levels. Goldenseal, an herb that contains berberine, cut metformin levels by about a quarter in 16 healthy adults, but in adults with diabetes already on metformin the overall change was too small to matter. (Kwon 2015, Nguyen 2021, Nguyen 2025, NCCIH)
  • Other medicines. When healthy men took berberine for 2 weeks (300 mg, three times a day), three liver enzymes that clear many drugs (CYP2D6, CYP2C9 and CYP3A4) slowed, and blood levels of a test drug rose 40%. (Guo 2012)
  • Stomach effects. Both can upset the stomach. In one pilot trial, 20 of the people taking berberine (34.5%) had passing stomach side effects, and diarrhea and nausea are among metformin's most common side effects. LiverTox has not linked berberine to liver injury. (Yin 2008, metformin label, LiverTox)

What to do

  • Tell your prescriber before you start berberine, and ask your pharmacist to check every other medicine you take against it, because of its effect on liver enzymes.
  • If you already check your blood sugar at home, check it more often after you start, as your prescriber advises. The metformin label says lows are more likely with insulin or a sulfonylurea, or if you don't eat enough, drink alcohol or take other sugar-lowering medicines. (metformin label)
  • Know the signs of a low: shaking, sweating, a fast heartbeat, hunger, nervousness, confusion or dizziness. A severe low can make you pass out, and the man in the case report fainted. (MedlinePlus, Janumet label, Henshall 2025)
  • Follow your prescriber's plan for treating a low, as the metformin label says, and tell them if lows happen. Call emergency services if someone passes out.
  • Berberine is not a stand-in for your diabetes medicine. Don't stop or change a prescribed medicine on your own.
  • If you're pregnant, planning a pregnancy or breastfeeding, ask your doctor or midwife first. NCCIH says berberine can harm newborns.

Sources

  1. Dong H, et al. Berberine in the treatment of type 2 diabetes mellitus: a systemic review and meta-analysis. Evid Based Complement Alternat Med. 2012. PubMed 23118793 · doi:10.1155/2012/591654
  2. Wang J, et al. Effects of administering berberine alone or in combination on type 2 diabetes mellitus: a systematic review and meta-analysis. Front Pharmacol. 2024. PubMed 39640489 · doi:10.3389/fphar.2024.1455534
  3. Xie W, et al. Glucose-lowering effect of berberine on type 2 diabetes: A systematic review and meta-analysis. Front Pharmacol. 2022. PubMed 36467075 · doi:10.3389/fphar.2022.1015045
  4. Henshall A, et al. Berberine-induced hypoglycaemia and electrocardiogram interpretation in athletes. BMJ Case Rep. 2025. PubMed 40903097 · doi:10.1136/bcr-2025-266876
  5. Kwon M, et al. Organic cation transporter-mediated drug-drug interaction potential between berberine and metformin. Arch Pharm Res. 2015. PubMed 25359200 · doi:10.1007/s12272-014-0510-6
  6. Nguyen JT, et al. Assessing Transporter-Mediated Natural Product-Drug Interactions Via In vitro-In Vivo Extrapolation: Clinical Evaluation With a Probe Cocktail. Clin Pharmacol Ther. 2021. PubMed 33174626 · doi:10.1002/cpt.2107
  7. Nguyen JT, et al. The Pharmacokinetic Interaction Between Metformin and the Natural Product Goldenseal Is Metformin Dose-Dependent: A Three-Arm Crossover Study in Adults With Type 2 Diabetes. Clin Transl Sci. 2025. PubMed 39943692 · doi:10.1111/cts.70120
  8. Guo Y, et al. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol. 2012. PubMed 21870106 · doi:10.1007/s00228-011-1108-2
  9. National Center for Complementary and Integrative Health. Goldenseal. Last updated February 2025. NCCIH
  10. US National Library of Medicine. Metformin hydrochloride tablets (Zydus): prescribing information. DailyMed, revised 07/2026. DailyMed
  11. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Berberine. NIDDK, updated 6 October 2020. NCBI Bookshelf
  12. Yin J, et al. Efficacy of berberine in patients with type 2 diabetes mellitus. Metabolism. 2008. PubMed 18442638 · doi:10.1016/j.metabol.2008.01.013
  13. US National Library of Medicine. Janumet (sitagliptin and metformin) tablets: prescribing information and patient information. DailyMed, revised 08/2026. DailyMed
  14. National Library of Medicine. Low Blood Glucose (Hypoglycemia). MedlinePlus. MedlinePlus