Last Tuesday, an inquest heard that a young woman who was taking the combined oral contraceptive (commonly referred to as 'the pill') developed deep vein thrombosis (DVT) and died. What was most perplexing about the death of Julie Hennessy (31), originally from Cork and living in Dublin, was that she was a non-smoker and of healthy weight, two major risk factors for women on the pill.

Dr Peter Szontagh-Kishazi, a pathologist at Blanchardstown hospital, told Dublin County Coroner's Court in no uncertain terms that the contraceptive pill was the cause of the DVT. "The only important factor was the oral contraceptive pill, " he said. "Clotting is a well-known risk of using the contraceptive pill. There is no other medication that has such a big risk as the oral contraceptive pill."

This definitive pronouncement from the pathologist . . . who ruled out Hennessy's knee injury while skiing earlier this year and the fact she had taken about 20 flights in the previous 18 months as contributory factors in her death . . . caused panic in the media. Hennessy had been taking the oral contraceptive Mercilon for a number of years prior to her death.

Outside court, her parents' words added to the escalation of concern. "The pill was the major cause of our daughter's death and we want to put it on record that other young women should be aware of these dangers, " her father Ray Hennessy said. "Doctors are aware of the risks but I want to warn young women of the possible consequences of taking it. I wouldn't like this to happen to another family."

Should women on the pill be concerned?

Yes and no. The resounding message from medical experts this past week has been "don't panic".

"Women who are taking the contraceptive pill should not panic, " said the Irish Family Planning Association (IFPA). "If women are concerned about taking the pill, they should make an appointment to see their GP or family planning centres and discuss any concerns they may have.

In the meantime, they should continue to take their contraception to avoid a crisis pregnancy or regulate their menstrual cycle."

The IFPA stressed that, for the vast majority of women, the benefits of the pill outweighed the possible risks. However, it pointed out that . . . in a very small number of cases . . . the pill can produce serious side effects, including blood clotting.

A European report in 2001 found that venous thrombo-embolism is a known rare side effect of all combined oral contraceptives. However, in women using a combined oral contraceptive pill containing desogestrel or gestodene, there is a small increased risk of venous thrombo-embolism.

The Irish Medicines Board issued communications to all 11,500 healthcare professionals in the country giving details of the review and advice for patients at the time.

What are the chances of developing a blood clot and does the pill increase risk?

All women are at risk of developing blood clots, and pregnant women more so, regardless of whether they are on the pill. Five in 100,000 women will develop blood clots and this risk increases to between 20 and 30 in 100,000 women on the pill, according to Dr Shirley McQuade, medical director of the Dublin Well Woman clinic. The risk of pregnant women developing blood clots is 50 in 100,000. But the development of a blood clot by no means ensures it will travel to the lungs causing DVT, McQuade stressed.

"Blood clots generally start below the knee in the calf muscle. The risk of a blood clot travelling from there to the lung is between 2-3%. And even then, the risk of it being fatal is less again. The vast majority of blood clots don't go anywhere. The woman's death highlighted at the inquest was an extremely rare and unfortunate event."

When a blood clot travels to the lung, it becomes a pulmonary embolism (PE).

"Those who develop a blood clot will have a hot, red, tender calf muscle. It will look bigger than the other. It won't necessarily be painful; some women aren't even aware of them and most just go away. But women should consult their GP if they notice swelling."

The fact Hennessy was young and healthy makes her death unusual and should serve as a warning to all women who do smoke or are overweight and taking the pill. "Smokers and overweight women should consider their options, " said McQuade. "The ideal would be to stop smoking. Women over 35 should definitely not be taking a contraceptive pill with oestrogen in it and consider other contraceptives. But one issue is that the combined contraceptive pill is the most effective for the majority of people."

What has been the reaction from Mercilon?

"It's a very tragic situation and we offer our condolences to the family, " a spokeswoman for Organon, which produces Mercilon, told the Sunday Tribune. A leaflet accompanying Mercilon tablets warns there is a risk of developing thrombosis. It also points out that the risk of developing thrombosis is higher when pregnant than when taking the tablets.

"We have no figures for the number of people taking Mercilon in Ireland but it's sold widely around the world. This reported death is the first that we are aware of in Ireland or the UK, " the spokeswoman added. The company will now "establish the facts" of Hennessy's death and decide upon a "responding process", she said.

The Well Woman centre in Dublin has also received some calls from concerned women asking if it is planning to discontinue the sale of Mercilon. "No, we are not, " says McQuade. "There is very little difference between that pill and the others so the risk factors are the same."

Are women really now worried about using the pill, or is it just media hysteria?

IFPA did not record an increase in calls from women concerned about the contraceptive pill last week. Neither have the Well Woman clinics, save for a few enquiries about Mercilon. The general public seems to grasp that this was a rare isolated incident, while sections of the media seem to be over-emphasising the implications of this tragic death.