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Is it true that taking St John's Wort means the pill doesn't work

01:00 Wed 28th Aug 2002 |

asks Mayastar:
You're talking about a recent report from Sweden where two women who were on the Pill became pregnant after taking St John's Wort for mild depression. There have been similar reports in this country, too.

Q. Why does it do that
St John's Wort affects enzymes in the liver that control the metabolism of certain drugs. As a result, you can end up with unusually high or low levels of these drugs in your body.

Q. But aren't herbal remedies natural
They are. But 'natural' should not be equated with 'safe'. Anything that is strong enough to have an affect on your body can also have an effect on the things you put into your body.

Q. Isn't St John's Wort safe, then
A. It is, if it's taken appropriately, it has been shown to have fewer side effects than many drugs taken for mild to moderate depression. However, it may not be safe if you take it while also taking prescription drugs.

Q. What sort of drugs does it interfere with
There is evidence that St John's Wort interferes with prescription drugs, including: cyclosporin, which is given to transplant patients; warfarin and digoxin, which are used for heart conditions; theophylline, which is used for asthma; SSRIs, which are used for depression; and triptans, for migraine.

Q. Do other herbal remedies affect prescription drugs
Yes. Although there hasn't been much research done into how drugs and herbs interact, it's known that feverfew, ginko biloba and dong quai may interfere with warfarin, for example. Echinacea must never be taken with drugs that can cause liver damage. Garlic supplements greatly reduce the efficacy of an anti-HIV drug, saquinavir. Sedative herbs, such as valerian, shouldn't be taken with sedatives.

That's why you must always tell your GP if you are on a prescription medication and decide to take a herbal remedy, too.

Q. What if my GP doesn't know much about herbal remedies
Most won't know much, but they can find out about them if you ask. A discussion with your GP is useful because most consumers know little about the remedies or drugs they are taking: a study by the School of Pharmacy found that 60% of people buying herbal remedies had taken them with conventional drugs, despite warnings on the labels. This is mainly because they don't consider certain drugs, such as the Pill, to be medications.

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By Sheena Miller

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