Ginseng

Is ginseng safe?

For most healthy adults, yes, at least for a few months. Asian ginseng (Panax ginseng, sold as Korean, red or white ginseng) has been used for centuries and studied in many small trials. The US National Center for Complementary and Integrative Health says use for up to six months in recommended amounts appears safe for most people. The most common complaint is trouble sleeping.

The cautions are narrower than for many herbs. Ginseng can blunt warfarin, may lower blood sugar, and has rare reports of liver problems and severe skin reactions. Product strength is unpredictable, and ginseng energy drinks often add caffeine.

What the trials show about side effects

The best overview is still a 2002 systematic review in Drug Safety that pulled together trials, manufacturer data and national reporting schemes. In clinical trials, side effects with single-herb ginseng were about as common as with placebo. The usual ones were headache, poor sleep and stomach upset. More serious reports existed, but mostly involved products mixing ginseng with other ingredients, which makes it hard to know what caused them.

The European Medicines Agency's monograph, last revised in 2024, lists stomach discomfort, nausea, diarrhoea or constipation, hives and itching, and insomnia, all with unknown frequency. No overdose cases are recorded. NCCIH adds rare reports of severe rash, liver damage and allergic reactions, and warns that ginseng may worsen autoimmune conditions.

One limit: NCCIH notes that most ginseng trials enrolled fewer than 200 people and lasted under three months. That is why the EU monograph caps use at three months for adults and does not recommend it for under-18s.

Ginseng and warfarin

This is the interaction most worth knowing. Two studies from 2004 reached different results for the two main species:

Study	Ginseng type	Result
Randomised trial, 20 healthy adults (Annals of Internal Medicine)	American (Panax quinquefolius)	Peak INR and warfarin levels fell after 2 weeks
Crossover study, 12 healthy men (British Journal of Clinical Pharmacology)	Asian (Panax ginseng)	No change in INR or warfarin levels

A lower INR means warfarin is working less well, which raises the risk of clots. Case reports of falling INR on Asian ginseng also exist. If you take warfarin, do not start or stop ginseng without telling the clinic that manages your INR.

Other interactions

• Diabetes medicines. Ginseng may lower blood sugar. Combined with metformin, insulin or sulfonylureas, the effect could add up.
• MAO inhibitors. The 2002 Drug Safety review lists reported interactions with phenelzine, an older antidepressant, and with alcohol.
• Imatinib. A 2010 case report described serious liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary in a man stable on imatinib for 7 years after three months of ginseng energy drinks; the authors suspect ginseng raised imatinib levels.
• Stimulants. Many ginseng drinks and "energy" capsules also contain caffeine. Insomnia, palpitations and nervousness are more likely with these than with ginseng alone; see caffeine pills for the doses that matter.

Overall, interactions with ginseng are much less common than with St John's wort. A 2017 review of human studies found mostly negative or weak effects on drug-metabolising enzymes. If you take any regular medicine, ask your doctor or pharmacist.

How strong is your ginseng?

Hard to tell from the label. When researchers analysed 25 US ginseng products in 2001, every one contained the right species, which is reassuring. But the amount of ginsenosides, the compounds thought to do the work, often did not match the label and varied about 15-fold between capsules and 36-fold between liquids.

The EU monograph shows how wide the range of legitimate products is: from 600 to 2,000 mg of root powder a day, to 40 to 200 mg of an extract standardised to 4% ginsenosides. Compare products by the type of preparation and ginsenoside content, not just milligrams. A licensed traditional herbal medicine in the UK or EU, or a USP VerifiedThird-party testingTesting of a supplement by an independent lab to check that it contains what the label says and is free of set contaminants.More in the glossary product in the US, gives more confidence about dose.

Who should be careful

• Anyone on warfarin or other anticoagulants.
• People with diabetes on glucose-lowering drugs.
• People with autoimmune disease or on immunosuppressants.
• Pregnant or breastfeeding women: the EMA advises against use because safety has not been established.
• Children and teenagers.
• People with insomnia or anxiety, who may find it makes sleep worse. Avoid taking it in the evening.

How we scored it

Regulatory actions (88) and dose safety (82) are the strongest factors: no bans and a side-effect rate close to placebo in trials. Interactions (68) reflect the warfarin and blood sugar effects, and product quality (62) the wide gap between labels and content. Ginseng scores above ashwagandha, which has a clearer liver signal and a ban in Denmark, and above ginkgo, mainly because ginseng products are less often adulterated and interact with fewer drugs.