St John's Wort 'Stops Morning After Pill From Working'

Time to talk to your pharmacist.

A common herbal medicine used to treat numerous health issues including epilepsy and fungal infections has been found to stop the morning after pill from working.

Medicines containing St John’s wort can reduce the effectiveness of levonorgestrel emergency contraception, according to the Medicines and Healthcare products Regulatory Agency (MHRA).

The MHRA has advised anyone taking St John’s wort to notify their doctor before taking the emergency contraceptive pill so they can be given a suitable replacement or higher dosage.

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Levonorgestrel is a type of emergency contraception that can be used within three days after unprotected sex or failure of a usual contraceptive method.

In its new guidelines, the MRHA advises people in need of this particular make of morning after pill to tell their doctor, pharmacist or nurse if they are currently taking, or have taken in the past four weeks, a medicine to treat the following:

  • Epilepsy - medicines called barbiturates, primidone, phenytoin or carbamazepine
  • Tuberculosis - rifampicin and rifabutin
  • HIV - ritonavir and efavirenz
  • A fungal infection - griseofulvin
  • Any herbal remedies containing St John’s wort (also kno Hypericum perforatum)

“If you are taking any medicines or herbal remedies and are not sure if they might affect levonorgestrel emergency contraception check with your doctor, pharmacist, or nurse,” reads the report.

People who are taking medicines containing St John’s wort have been advised to use another type of emergency contraception called a copper intrauterine device or ‘coil’ inserted into the womb, which does not interfere with other medicines.

If that is not an option, they are advised to take a double dose of levonorgestrel emergency contraception.

“The pharmacist will give you two packs, which should be taken together at the same time,” says MRHA.

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