The combined contraceptive pill and DVT: What are the risks and how can they be reduced?
By Davina Fenton
Amid concern about a lack of awareness of the small link between use of the combined pill and deep vein thrombosis, here is a look at some key facts and potential risks.
What is the combined pill?
This oral contraceptive commonly referred to "the pill", contains artificial versions of the female hormones oestrogen and progesterone, which women produce naturally in their ovaries.
What are the main advantages of using the pill?
Aside from its effectiveness in preventing pregnancy, using the pill can reduce the risk of cancer of the ovaries, womb and colon, as well as symptoms of pre-menstrual syndrome and even acne, according to NHS choices.
It can also protect against pelvic inflammatory disease and reduce the risk of fibroids, ovarian cysts and non-cancerous breast disease.
And the disadvantages?
It can cause temporary side effects, such as headaches, nausea, breast tenderness and mood swings.
It can also increase your blood pressure and has been linked to an increased risk of some serious health conditions, such as breast cancer and thrombosis (blood clots).
The risk of blood clots and the pill
There is a well established link of a “rare but important risk" of developing a blood clot (thrombosis) from using the combined contraceptive pill.
The female hormone oestrogen it contains can cause clotting of the blood more readily, leading to blood clots in the veins or venous thromboembolism (VTE), such as:
Deep Vein Thrombosis (DVT): a clot in in one of the deep veins in the body, usually in one of the legs
Pulmonary embolism. This is when in the case of DVT, a piece of blood clot breaks off into the bloodstream and blocks one of the blood vessels in the lungs. In severe cases, this can be fatal.
A blood clot could also form in the vessels of the heart (causing a heart attack) or the brain (causing a stroke).
Check your potential risk of developing blood clots
This is a tool provided by NHS choices, and ITV is not responsible for either the tool or the results.
In 2015, Fallan Kurek, 21, died from a "massive" pulmonary embolism linked to the side-effects of the contraceptive pill were not effectively treated.
Reducing the risk of a developing a blood clot
Doctors are given clear guidelines for prescribing the pill and before doing so should check if you have certain risk factors that make you more vulnerable to this complication.
These include:
being 35 years old or over
being a smoker or having quit smoking in the past year
being very overweight
high blood pressure
having had a blood clot or stroke in the past
a family history of a blood clot
being immobile for a long time
How to tell if you might have a DVT or pulmonary embolism
Symptoms can include:
cramping pain, redness, warmth, or swelling in one of your legs – these are symptoms of DVT
breathlessness, chest pain, fainting or coughing up blood – these are symptoms of a pulmonary embolism
Do some pills carry more risk of causing blood clots that others?
Some types of the pill appear to be associated with a slightly higher risk of a serious blood clots, depending on the type of progestogen hormone it contains, research suggests.
For example, in 2015, scientists at the University of Nottingham found pills with newer types of progesterone hormones (drospirenone, desogestrel, gestodene, and cyproterone) could come with an increased risk.
Those that are considered to have the lowest risk of blood clots contain the older progestogens levonorgestrel, norgestimate or norethisterone.
Responding to the findings at the time, Dr Helen Stokes-Lampard from the Royal College of GPs, said: “The combined pill is an excellent contraceptive choice for the majority of women.
The Medicines and Healthcare Products Regulatory Agency (MHRA) also advises that the risk is "small" and doctors and patients should consider risk factors and remain "vigilant for signs and symptoms".
Other factors which can increase the risk of DVT
Long distance car, train, coach or plane journeys may also increase the risk of thrombosis.
During periods of inactivity your blood flow can slow down considerably, increasing the chances of a clot forming.
That’s why hospital patients that are immobile for a long period of time after an operation, illness or injury are at increased risk.
The risk of DVT from the pill increases with other risks such as flying, leg injury and being overweight, according to leading vascular surgeon, Professor Charles McCollum.
He advises women on the pill to wear elastic compression stocks and to take an aspirin before a long flight or coach journey.
Most blood clots 'develop during or after hospital stay '
In fact, despite blood clots being linked to the contraceptive pill or long-haul flying, most blood clots actually develop during or just after a stay in hospital, according to NHS Choices.
Those at risk of DVT or who have had the condition previously are advised to keep hydrated, perform simple leg exercises, and take occasional short walks where possible, and wear elastic compression stockings.
A matter of weighing the risks?
The general medical consensus based on existing research and reviews is that the effectiveness of contraceptive pills in preventing unwanted pregnancies continue to “far outweigh their risks”.
An MHRA spokesperson told ITV News "these are very safe, highly effective medicines", adding that women "should be aware of the major risk factors for blood clots, and the key signs and symptoms".
Useful links:
NHS Choices has a full guide to the combined pill
Sexual health charity FPA's My Contraception Tool can help women consider which birth control method may be most suitable for them.
Brook's website also has a wide range of information on various forms of contraception
The Sexual Health Line on 0300 123 7123
Sources: NHS, MHRA, British Medical Journal, European Medicines Agency, NICE: reducing the risk of VTE