Berberine

Sold for blood sugar, weight and cholesterol, and online as a natural alternative to the weight-loss injections. It does a little, clashes with many medicines, and metformin does more for less.

At a glance

Our verdict	Lowers blood sugar a little (about 0.4%), never tested on heart or kidney outcomes, and blocks the enzymes that clear many medicines.
Sold for	Blood sugar, weight and cholesterol (claimed)
How sure the evidence is	Low to Very low
Cost a month	About $20 to $34

Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.

Supplement Check

Is it right for you?

Already taking berberine? It changes the levels of many common medicines. Your check tells you whether to stop it, and what would work better. Our Supplement Check looks at:

Pregnancy and breastfeeding: do not take it (newborn jaundice)
Anyone taking a medicine in the table above
Kidney or organ transplant
Cancer, especially on tamoxifen or an oral cancer medicine
G6PD deficiency
Every medicine you take

Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.

$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check

Tell me when it opens

What it is

Berberine is a plant alkaloid from Coptis (huang lian), Phellodendron, barberry, goldenseal and Oregon grape. Most trials used berberine hydrochloride. Shelf products also include whole-herb extracts (goldenseal, Coptis), whose berberine content varies, and “dihydroberberine” or “phytosome” forms marketed as better absorbed, which have no glucose trials. Less than 1% of a dose of berberine hydrochloride is absorbed.

Structure of Berberine — Structure: PubChem (public domain).

How it acts

Mostly in the gut and liver. It switches on an energy-sensing enzyme (AMP-activated protein kinase) in a way that resembles metformin, increases insulin receptors, reduces glucose absorption from the gut, and changes gut bacteria and bile acids. It lowers LDL cholesterol a little by keeping more LDL receptors on liver cells. [1, 2]

Outline of a person showing where Berberine acts in the body

What it is used for, and what the evidence says

Use	What the trials found	How sure we are
Type 2 diabetes, average blood sugar (HbA1c)	Pooled reviews of 27 to 50 trials report HbA1c 0.5 to 0.7% lower. [3, 4] But almost all were done in China, many published in Chinese-language journals, most lasted 8 to 12 weeks, and many were open-label. An audit of “randomised” trials in Chinese journals found only 6.8% were truly randomised. [5] The effect shrinks to nothing in trials longer than 90 days and in people over 60, a pattern that points to small-study bias. The best-run placebo-controlled trial (409 people, 20 centres) found 0.4% more than placebo. [2] A pharmaceutical berberine salt (not sold as a supplement) gave 0.4 to 0.7%. [6] Our best estimate: about −0.4%, possibly zero.	Low
Prediabetes	No adequately sized trial. No trial has measured whether it prevents diabetes.	Very low
Head to head with metformin	Small trials (about 18 people per group) reported “similar” results. [7] None was designed to prove the two are equal; “no significant difference” in a trial that small is not equivalence.	Very low
Weight	Between 0 and 2 kg in pooled trials. [8, 9] The claim that it works like the weight-loss injections is false: semaglutide 2.4 mg lowered body weight by 14.9% against 2.4% with placebo. [10] In a 2026 trial of 337 people taking 1 g a day for 6 months, berberine did not reduce belly fat or liver fat. [11]	Very low
LDL cholesterol	Berberine alone: about 0.24 mmol/L lower, and the range includes zero. [12] A statin lowers LDL by 30 to 50%.	Very low to Low
Heart attack, stroke, kidney failure, death	No trial of berberine has measured any of them.	No evidence

How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.

Benefits

Average blood sugar (HbA1c), type 2 diabetes: About −0.4% (0 to −0.7); Low
Fasting blood sugar, type 2 diabetes: About −0.5 mmol/L; Low
Prediabetes: Unknown; Very low
Body weight: 0 to −2 kg; Very low
LDL cholesterol: About −0.24 mmol/L, may be zero; Very low to Low
Triglycerides: About −0.2 mmol/L; Low
Heart, kidney, death: Not studied; No evidence

Risks and side effects

Gut upset: constipation, diarrhoea, cramps, bloating, nausea. About a third of people in one trial. [7]
Low blood sugar when added to insulin or a sulfonylurea (gliclazide, glyburide, glimepiride).
Jaundice in newborns. Berberine pushes bilirubin off its carrier protein far more strongly than some medicines known to do this; [13] herbs containing it were banned in Singapore for about 30 years after newborn jaundice and brain injury in babies with G6PD deficiency. [14]
Unreliable products. About 45% of berberine and goldenseal products tested in 2023 had a problem: under-filled, lead contamination, or almost no berberine.

Interactions with medicines

This is the main reason we do not recommend it. Measured in people, not just in the test tube: two weeks of berberine at a lower dose than the 1,500 mg a day usually sold strongly blocked CYP2D6 (ninefold), and also blocked CYP2C9 and CYP3A4, three of the liver enzymes that clear most medicines. [15] In 52 kidney-transplant patients, berberine raised ciclosporin levels by 29% or more. [16]

Medicine	What can happen	What to do
Ciclosporin, tacrolimus, sirolimus	Higher levels, toxicity	Do not take; doctor told the same day
Tamoxifen	Less of the active drug; lower cancer protection	Do not take; doctor told the same day
Warfarin, phenytoin, celecoxib	Higher levels; bleeding with warfarin	Do not take; same day for warfarin
Simvastatin, lovastatin, atorvastatin	Higher statin levels, muscle damage	Do not take
Codeine, tramadol	Less pain relief	Do not take
Metoprolol, carvedilol, propafenone, flecainide	Higher levels, slow heart rate	Do not take
Paroxetine, fluoxetine, venlafaxine, tricyclics, atomoxetine, aripiprazole, risperidone	Higher levels	Do not take
Insulin, gliclazide, glyburide, glimepiride	Low blood sugar	Do not take; same day
Midazolam, triazolam, quetiapine, calcium-channel blockers, apixaban, rivaroxaban, ticagrelor, many oral cancer medicines	Higher levels	Do not take
Metformin, SGLT2 inhibitors, GLP-1 medicines	Added blood-sugar lowering; more gut upset with metformin	Discuss with your doctor
Digoxin, dabigatran	Possible change in levels (little human data)	Discuss with your doctor

Who should not take it

Pregnancy and breastfeeding: do not take it (newborn jaundice).
Anyone taking a medicine in the table above.
Kidney or organ transplant.
Cancer, especially on tamoxifen or an oral cancer medicine.
G6PD deficiency.
Diabetes treated with insulin or a sulfonylurea.
Severe kidney disease or cirrhosis of the liver (no data).
Under 18.
Older adults on several medicines: interactions are likely, and the effect was smaller over 60.

Dose and timing

We do not recommend a dose. For reference, trials used berberine hydrochloride 0.9 to 1.5 g a day, split into 2 or 3 doses with meals, for 1 to 3 months; higher doses did no better. Canadian labels say to discuss use beyond 3 months with a doctor.

If you take it now: the only way to know whether it works is an HbA1c test after 3 months. The expected change (about 0.4%) is barely more than the test's own variation (0.2 to 0.3%), so in one person it may be impossible to tell.

What we know about Canadians

Berberine is sold in Canada as a licensed natural health product with the claim “helps support healthy glucose metabolism”. That is a support claim, not a diabetes-treatment claim; some Canadian retail pages go further than the licence allows. Few Canadian brands publish batch heavy-metal results.

Interest in weight-loss medicines is high and largely self-funded: public drug plans spent $807 million on semaglutide in 2024, the single largest driver of growth in public drug spending, and most public plans still cover these medicines for diabetes only. [17] That gap is where berberine is sold as a natural alternative. Nearly half of Canadians (45.6%) took a supplement in 2015. [18]

How sure are we: not graded. No Canadian data on berberine use or on diabetes in this review; the text is from the licence wording and Canadian supplement-use and GLP-1 spending data.

An honest comparison: blood sugar in type 2 diabetes

Same outcome (HbA1c, average blood sugar over 3 months), same units, cost a month in Canadian dollars before any drug plan.

Option	Effect	How sure we are	Cost a month (CAD)
Soluble fibre, about 13 g a day	HbA1c −0.58% [21]	Moderate	$15 to $30
Berberine 1,500 mg a day	HbA1c about −0.4% (0 to −0.7); weight 0 to −2 kg; no outcome data	Low	$20 to $34
Structured exercise (aerobic and strength, over 150 minutes a week)	HbA1c −0.67%; −0.89% above 150 minutes a week [19]	Moderate to High	$0 (walking) to $40–80 (gym)
Weight loss (intensive programme)	58% fewer new cases of diabetes in prediabetes; [20] 46% remission of diabetes at a year in one trial	High	$0 to $250
Metformin (generic)	HbA1c −1.1%; [22] fewer heart attacks and deaths in overweight people with diabetes; [23] 31% fewer new cases of diabetes [20]	High	$8 to $15
SGLT2 inhibitors (empagliflozin, dapagliflozin)	HbA1c −0.5 to −0.8%; heart-failure admissions −31%, kidney decline −45% [24]	High	$70 to $115 (generic dapagliflozin)
GLP-1 medicines (semaglutide)	HbA1c −1.5 to −1.8%; weight −14.9% at the obesity dose; [10] fewer heart attacks and strokes	High	$220 to $260

Read honestly: berberine's best estimate is below soluble fibre, below structured exercise, about a third of metformin and a quarter of semaglutide, with no outcome data and the worst interaction profile on the list. Metformin costs less.

Why we don't recommend it

We do not sell berberine and our check never recommends it. It lowers blood sugar a little, the size of the effect is inflated by small, low-quality trials, it has never been shown to prevent heart disease, kidney disease or diabetes complications, and it changes the blood levels of many common medicines.

Already taking it? Discuss it with your doctor. Stop it now if you are pregnant, planning a pregnancy or breastfeeding, or if you take a medicine in the interaction table. If your blood sugar is rising, ask your doctor about metformin: it lowers HbA1c about three times as much, costs less, and has decades of safety data.

Dr. French reviewed berberine against metformin, the SGLT2 inhibitors and the GLP-1 medicines and was not convinced. Its best-estimate effect is small and inflated by small, low-quality trials; it has no heart, kidney or survival data; and in people it blocks three of the liver enzymes that clear most medicines. A generic medicine that does more, with decades of outcome data, costs less. So we do not sell it, and if you already take it, discuss it with your doctor.