There was bad news last month for the many women who are regular users of black cohosh - a natural herbal remedy for menopausal symptoms such as hot flushes. The European Medicines Agency has now linked the herb to the possibility of liver damage.

Black cohosh is widely used by women on every continent. It’s thought to help with menopausal symptoms because it contains phytoestrogens - substances that behave a lot like the hormone estrogen. One cause of menopausal symptoms is a big drop in estrogen levels. The phytoestrogens in black cohosh are thought to help by taking the place of the missing estrogen in a woman’s body.

Three years ago scientists in the US first warned about possible dangers of the herb. Stanley M. Cohen, MD, assistant professor of medicine at the University of Chicago, reported that he and colleagues had diagnosed what they believed to be the first case of autoimmune hepatitis caused by the use of this popular herb.

Last month the European medicines watchdog joined the debate and issued a warning that use of the herb may be linked to liver damage.

The European Medicines Agency now advises people to stop taking the herb immediately if they have any symptoms suggesting liver injury, such as tiredness, loss of appetite, yellowing of skin and eyes, severe upper stomach pain with nausea, or dark urine.

Fortunately, Dr Cohen’s earlier research showed that with prompt diagnosis and therapy, most people recover.

“If you’re taking black cohosh, ask your doctor for liver function tests,” he advised. One of his patients had been taking the herb for only a few weeks when symptoms developed.

In Britain, the Medicines and Healthcare products Regulatory Agency (MHRA) said that a review of all available data had concluded that liver injury resulting from black cohosh was rare, but could nevertheless be serious.

“In the light of this advice, the MHRA is working with the herbal sector to ensure that labels of black cohosh products carry updated safety warnings,” Professor Kent Wood, the agency’s chief executive, said in a statement.

“The labels will point out the possible symptoms so that appropriate action can be taken without delay.”

The warning is sad news for the women looking for a natural solution to ease the symptoms of menopause, who assumed that a herbal remedy such as this was a safe option.

Black cohosh has been used for many years in Europe and North America, and gained popularity after a highly publicised study in 2002 found that hormone replacement therapy raised the risk of heart attack, stroke and breast cancer.

But very little research has been done to test the effectiveness and safety of black cohosh (and many other supplements) for treating hot flushes.

More bad news…breast cancer links

A further study has now sounded warning bells linking black cohosh to a more aggressive form of breast cancer. There is some evidence from a study done on mice that suggests black cohosh may actually make breast cancer more likely to spread to other organs or tissues.

Researchers in this study used more than 200 female mice that were especially prone to developing breast cancer (all the mice had genetic abnormalities equivalent to HER2/neu abnormalities in humans).

Half the mice were fed a standard diet plus a daily amount of black cohosh. The other half received just a standard diet, without any black cohosh. The amount of black cohosh given to the first half was comparable to the amount that women take to relieve menopausal symptoms (45 milligrams for every 1,800 calories in the diet).

Researchers then looked at how many, and what type of breast cancers developed in the mice receiving the black cohosh compared to those who got the standard diet.

The animals that got the black cohosh did not have significantly more breast cancers than the other group - but nearly three times more breast cancers had spread to the lungs in the animals fed the black cohosh (27%) as compared to those given the standard diet (11%).

These results suggest that black cohosh supplements might not affect your risk of developing breast cancer. But if breast cancer does develop, black cohosh may make it more aggressive and likely to spread to other organs or tissues.

This small study was done in animals, so its findings are not as reliable as those of larger studies done in women. But it suggests that you may want to think twice before taking black cohosh supplements to relieve your menopausal symptoms. This herbal remedy may NOT be a safer alternative to standard HRT, especially if you have already had breast cancer.

Check what you’re taking!

Black cohosh is used in a range of licensed and unlicensed products across Europe. In addition to treating menopause symptoms, in some countries it is also used for rheumatic pain, cough, stomach cramps and period pains - so look out for it as an ingredient in other herbal compounds.