A new warning about the effect of the herbal remedy St John's Wort on the contraceptive pill has been issued after two Swedish women had unwanted pregnancies.
The country's pharmaceutical regulator, the Medical Products Agency (MPA), has issued a new warning about the herbal extract.
St John's Wort is often taken to alleviate mild depression.
But it is known to counteract the effect of certain drugs, including hormone-based contraceptives, HIV medicines, blood-thickening drugs, and cyclosporine, a drug used to prevent rejection of organ transplants.
Swedish health experts said the herbal extract contained a substance called hyperfourin, which made the liver work more efficiently, helping it break down the pharmaceutical chemicals.
They suggest some products may have more of an effect on conventional medications than others.
The two Swedish women, aged 28 and 31, became pregnant even though they were taking the pill.
Authorities in the UK have had seven reports since February 2000 of women becoming pregnant while using oral contraceptives and St John's Wort - one had also used emergency contraception.
In a separate case, a woman became pregnant while taking St John's Wort, after taking emergency contraception.
The MPA in Sweden says it now wants a compulsory labelling warning of the interactions of all St John's Wort products, apart from tea.
This most definitely isn't the first report about St.John's Wort influencing hormonal birth control, but I thought it would be good to remind everyone that it's important to mention all your medications, food supplements and herbal remedies to your doctor when giving your medical history (and keeping her/him update on this list during every check up, too) and to keep in mind that hormonal birth control can fail for reasons that you don't quite think about (so keep using those condoms).
Just a little reminder.