Berberine and Medication Interactions: What to Check Before You Start

Berberine can change how your body processes some medicines. In a human study it slowed three liver enzymes that break down many common drugs, and it raised blood levels of the transplant drug ciclosporin. Berberine isn't suitable in pregnancy or breastfeeding or for babies, and if you take any prescription medicine, check with your GP or pharmacist before starting it.

This guide explains which medicines are most affected, the common side effects, who should avoid berberine and a checklist to work through first. For general advice on combining supplements safely, see how to build a safe supplement routine.

Why does berberine interact with medicines?

Because it slows the liver enzymes that clear many medicines from your body. Those enzymes belong to a family called cytochrome P450 (CYP), and if something slows them, a medicine can stay in your body longer and reach higher levels than intended.

That's what a 2012 study in healthy men found. After two weeks of berberine at 300 mg three times a day, activity of the enzymes CYP2D6, CYP2C9 and CYP3A4 all fell. One marker of CYP2D6 activity rose ninefold and one for CYP2C9 doubled, and the authors concluded that drug interactions should be considered whenever berberine is used. The European Food Safety Authority's 2026 draft opinion reached the same view on CYP3A4.

NovusDNA is a UK supplement brand making clearly labelled, science-led supplements tested by Campden BRI, a UKAS-accredited UK laboratory. Its Metabolic+, NovusDNA's berberine and milk thistle formula, contains berberine, which is exactly why we've written this guide. We'd rather you knew the interaction risks before buying than found out afterwards.

Which medicines are most affected?

Berberine and metformin

There isn't enough evidence to say the combination is safe for you. The NHS page on metformin says there's not enough information to say herbal remedies are safe to take with it, and asks you to tell your doctor or pharmacist about any supplements.

What are the common side effects?

Mostly stomach-related. The US National Center for Complementary and Integrative Health (NCCIH) lists abdominal pain, constipation, diarrhoea, nausea and vomiting as the most common, and EFSA describes them as transient.

On the liver, the US LiverTox database says berberine hasn't been linked to published cases of clinically apparent liver injury.

The bigger open question is long-term safety. EFSA's draft opinion, endorsed in January 2026, noted lab evidence of genotoxicity and concluded that the available data don't allow a safe intake to be established for any of the berberine preparations it assessed. Its consultation ran until July 2026, and the UK Committee on Toxicity has been reviewing it. Neither is a final ruling, but both are reasons to treat berberine as a considered, short-term choice.

Who should avoid berberine?

1. Pregnant or breastfeeding women: Memorial Sloan Kettering advises avoiding it.

2. Babies: NCCIH warns berberine can cause or worsen jaundice in newborns, which can lead to a serious condition called kernicterus.

3. People on ciclosporin, tacrolimus or other immune-suppressing medicines, unless their specialist has agreed it.

4. Anyone taking prescription medicines who hasn't checked with a GP or pharmacist first.

What about milk thistle?

Metabolic+ also contains milk thistle, which has its own, weaker interaction profile. Memorial Sloan Kettering's milk thistle monograph says it can inhibit CYP3A4 and affect medicines processed by that enzyme, though some data show no such effect. It also reports a case where a supplement containing milk thistle was linked to a rise in INR, a blood clotting measure, in someone taking warfarin. We explain why milk thistle is included in Metabolic+ separately.

Your checklist before starting berberine

1. List everything you take, including prescription medicines, over-the-counter medicines and other supplements.

2. Ask a pharmacist. The NHS advises always checking with a pharmacist before taking a herbal medicine if you already take other medicines.

3. Never stop a prescribed medicine to try berberine.

4. Check the dose on the label and don't exceed it.

5. Tell any doctor treating you that you take it.

6. Report side effects through the MHRA's Yellow Card scheme, which accepts reports about herbal products from anyone.

For more on what Metabolic+ contains and who it's designed for, see what Metabolic+ is and who it's for.

FAQ

Can I take berberine with metformin?

Speak to your GP or pharmacist first. The NHS says there isn't enough information to say herbal remedies are safe with metformin. A 2022 meta-analysis didn't find a significant rise in low blood sugar when berberine was combined with glucose-lowering drugs, but the authors rated that evidence as very low certainty. Never stop or change metformin without medical advice.

Can I take berberine with statins?

One study in 60 healthy volunteers found no clinically obvious interaction between berberine and simvastatin. However, berberine slows CYP3A4, an enzyme that breaks down several statins and other medicines, and the NHS advises telling your doctor about any supplements before taking simvastatin. Check with your pharmacist about your specific statin.

Is berberine safe for the liver?

The US LiverTox database says berberine hasn't been linked to published cases of clinically apparent liver injury. That doesn't rule out other risks: EFSA's 2026 draft opinion raised concerns about drug interactions and lab findings on genotoxicity, and said a safe intake couldn't be established.

How long after taking berberine can I take my medicine?

There's no evidence that spacing doses avoids the interaction. In the 2012 study, the effect on liver enzymes was measured after two weeks of repeated use, not just after a single dose. Ask your pharmacist whether berberine is suitable with your medicines at all, rather than relying on timing.

Can I take berberine if I'm pregnant or breastfeeding?

No. Memorial Sloan Kettering advises avoiding berberine during pregnancy and breastfeeding, and NCCIH warns it can cause or worsen jaundice in newborns, which can lead to kernicterus. It shouldn't be given to babies.

Berberine interactions are real: it changes how your liver processes some medicines, it's unsuitable in pregnancy and breastfeeding, and regulators in Europe and the UK are still reviewing its safety. If you take any medicine, a five-minute conversation with a pharmacist comes first. If you take none, read the label, start at the stated dose, and stop if you get side effects.

If a pharmacist or GP confirms berberine suits you, you can review the 7-day Metabolic+ pack and its full ingredient list before committing to a month.

This article is for general information and isn't medical advice. Speak to your GP or pharmacist before taking berberine if you take any medicine or have a medical condition. Food supplements should not replace a varied, balanced diet and healthy lifestyle. Do not exceed the stated recommended daily dose.