Berberine is one of the most popular natural supplements in the UK, but it is not right for everyone. If you are wondering who should not take berberine, this guide explains the people who should avoid it or only take it under medical supervision, the medicines it can interact with, and the side effects worth knowing about — so you can make a safe, informed decision.
Berberine is a plant compound found in shrubs such as barberry and goldenseal. It is sold in the UK as a food supplement — it is not a medicine, and it is not a substitute for advice from your GP or pharmacist. That distinction matters most for the groups below.
Who should not take berberine?
Several groups should avoid berberine, or speak to a healthcare professional before trying it:
Pregnant and breastfeeding women
Berberine is not recommended during pregnancy or while breastfeeding. It can cross the placenta and pass into breast milk, and health-information services such as the MotherToBaby berberine fact sheet advise avoiding it because of concerns about its effect on a developing baby and newborns. If you are pregnant, trying to conceive or breastfeeding, do not take berberine unless your doctor specifically advises it.
Anyone taking medication for blood sugar
Berberine has been widely studied for its effect on blood sugar, which is exactly why it can be a problem alongside diabetes medication such as metformin or insulin. Combining them may push blood sugar lower than intended. If you take any blood-sugar medication, speak to your GP or pharmacist before adding berberine.
People taking blood pressure medication
Berberine has also been studied for effects on blood pressure, so taking it with blood pressure medication could add to that effect. Anyone managing high or low blood pressure with medication should get professional advice first.
People with a liver condition
Berberine is processed by enzymes in the liver, and research on berberine and liver enzymes shows it can influence how the liver metabolises other substances. If you have a liver condition, check with your doctor before use.
People with a thyroid condition
Evidence here is limited, but because thyroid conditions are often medicated and finely balanced, it is sensible to speak to your GP before combining berberine with thyroid treatment.
Can berberine cause thyroid problems?
There is no strong evidence that berberine directly causes thyroid problems in healthy adults. The caution here is more about interaction than harm on its own: because berberine can influence liver enzymes and digestive absorption, it may affect how well thyroid medication (such as levothyroxine) is absorbed or processed. If you have a diagnosed thyroid condition, take thyroid medication at a consistent time apart from any supplement, and check with your GP or pharmacist before adding berberine to your routine.
Before surgery, and for infants and children
Because berberine may affect blood sugar, stop taking it at least two weeks before any planned surgery and tell your surgeon. Berberine should not be given to newborns or young children.
Can you take berberine with alcohol?
It's best to be cautious. Both alcohol and berberine are processed by the liver, and alcohol can also affect blood sugar levels, which overlaps with berberine's own effect on glucose. An occasional drink isn't necessarily a problem for a healthy adult, but regular or heavy alcohol use alongside berberine is worth avoiding, and anyone with a liver condition or on blood-sugar medication should be particularly careful.
Berberine and prescription medication: possible interactions
The main safety issue with berberine is not the supplement on its own — it is how it behaves alongside prescription medicines. A human study on berberine and cytochrome P450 enzymes found it can inhibit some of the liver enzymes that break down many common drugs. When those enzymes are slowed, medication can build up in the body. Take particular care — and get professional advice — if you use:
- Diabetes medication (metformin, insulin) — risk of blood sugar dropping too low.
- Blood pressure medication.
- Medicines processed by the liver, such as certain statins, immunosuppressants (e.g. ciclosporin) and some sedatives.
- Blood thinners — always confirm with your pharmacist.
If you are on any regular medication, the safest step is a quick check with your pharmacist before starting berberine. For a fuller breakdown of what not to combine with berberine, see our what not to take with berberine guide.
Is berberine safe to take?
For most healthy adults who are not pregnant, breastfeeding or on interacting medication, berberine taken at typical doses and for a limited period is generally well tolerated. It is still a food supplement rather than a medicine, so it should support a balanced diet and healthy lifestyle, not replace them — and it is not intended to diagnose, treat or cure any condition. General guidance on using supplements sensibly is available from the NHS.
Berberine side effects to be aware of
When side effects do occur, they are usually digestive and mild — cramping, diarrhoea, constipation or bloating, especially at higher doses. Taking berberine with food and splitting the dose across the day can help. Stop and speak to a healthcare professional if you experience anything more than mild, short-lived discomfort.
How to take berberine safely
A standard UK serving is 500mg per capsule, up to 1000mg per day. Because a single large dose is more likely to upset the stomach, it is usually split — for example one capsule with two main meals — and taken with food. If you are new to it, start with a lower amount and build up. Our capsules use the standard berberine form (not berberine HCl).
If you have read the cautions above and berberine is right for you, our UK-made capsules provide 500mg per serving:
Berberine is often part of a wider gut and metabolic routine. You can browse the full range here:
The bottom line
So, who should not take berberine? Avoid it if you are pregnant, breastfeeding or trying to conceive; be cautious and seek advice if you take medication for blood sugar, blood pressure, your thyroid or your liver; avoid combining it with regular alcohol use; and stop it before surgery. For everyone else, use it sensibly at the recommended dose — and when in doubt, ask your GP or pharmacist.
