Medicines which contain St John’s Wort ‘stop the morning after pill from working’
Women who take other drugs may need a double dose of the pill after research found hundreds of unwanted pregnancies
WOMEN taking the morning after pill with other drugs may need a double dose to stop them getting pregnant, research reveals.
Experts have issued the warning after research found there were 400 unwanted pregnancies linked to pills containing levonorgestrel since the 1970s.
The progesterone stops ovaries releasing eggs and irritates the lining of the uterus – making it difficult for a fertilised egg to implant.
But when it is paired with medicines for epilepsy, herbal remedies containing St John’s Wort, and drugs for fungal infections, women may need a double dose to make it effective.
Drugs for tuberculosis and HIV were also found to interfere with the effectiveness of the pills.
The Medicines and Healthcare products Regulatory Agency (MHRA) said the non-hormonal coil was the most suitable form of emergency contraception for those taking the daily medications.
Dr Sarah Branch, deputy director of MHRA’s vigilance and risk management of medicines division, said: “This is important new advice for women who want to use the emergency contraceptive pill.
“It will help to protect women who are taking certain medicines against unwanted pregnancies.”
She continued: “Our new patient information sheet provides information on what types of medicines could interfere with how the emergency contraceptive works.
“It tells women what steps they need to take to ensure they receive the correct dose.
“The earlier that emergency contraception is taken after unprotected intercourse, the better it works.”
The MHRA said it had data on 400 unwanted pregnancies in women taking levonorgestrel since it was first licensed in the 1970s.
But a spokesman said it was not clear how many of these pregnancies were due to interactions with other drugs, although research had found a link.
The new information sheet will be available through GP surgeries and pharmacies.
Levonorgestrel has to be taken within 72 hours (three days) of unprotected sex.
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