St John's wort, used to combat low moods, can reduce the effectiveness of the contraceptive pill.

London - Herbal medicines can pose serious health risks that consumers are not warned about, researchers say.

They surveyed different versions of the five most popular remedies - St John’s wort, Asian ginseng, echinacea, garlic and ginkgo - and found they were commonly sold over the counter with no safety warnings.

Yet St John’s wort, widely used to combat low moods, can reduce the effectiveness of the contraceptive pill.

Ginkgo, which is said to improve circulation and alertness, is also a blood-thinner that should not be combined with other medication.

And Asian ginseng, used to boost the immune system, and echinacea, often used to protect against colds, also have their dangers.

Even garlic used to lower high blood pressure can be dangerous in large quantities.

The researchers at Leeds University’s school of pharmacy surveyed 68 products on sale to the public and found 51 of them (75 percent) contained no information on precautions, interactions with other medicines or side effects.

Seventy percent of them (48 of the 68 products) were marketed as food supplements, despite their powerful effects.

Just three products contained sufficient information on risks and side effects.

The products were bought at two health-food stores, three chain pharmacies and three supermarket chemists.

Under an EU directive in April, certain herbal medicines have to be licensed and carry health information, but of these five products, only St John’s wort and echinacea require a licence.

Of the 12 St John’s wort products surveyed, four contained no safety messages, and of 13 echinacea products, nine failed to provide the required information.

The other three remedies do not have to carry any warnings, as long as they make no medical claims.

The fact that so few products provided sufficient information could be because shops are allowed to continue selling old stock, with no warnings, until their expiry date.

Professor Theo Raynor, who led the study, said: “The best advice to consumers is buyer beware. Herbal medicines… should be taken with as much caution as any over-the-counter medicine.

“Any substance that affects the body has the potential to do harm if not taken correctly.”

People should tell their doctor about the herbal medicines they are taking so that they receive the best care, he said. – Daily Mail

Popular but dangerous...

ST JOHN’S WORT: Reduces the effectiveness of the contraceptive pill and blood-thinning medication such as warfarin. It can increase the side effects of anti-depressants and may also raise blood pressure.

ECHINACEA: Should not be taken by allergy-prone people or those with asthma. It can cause asthma attacks and abdominal pain.

ASIAN GINSENG: Can be dangerous for diabetes patients because it may lower blood-sugar levels.

GINKGO: Can stop the blood clotting, so should not be taken before surgery or dental work.

GARLIC: Causes allergies and thins blood, so should not be taken before surgery. It also reacts badly with some medications, including HIV drugs.