There are many different brands of combined contraceptives, and most women can find one that is right for them. Rigevidon is one of the most commonly prescribed combined contraceptives and is no different in terms of hormone concentrations from Microgynon, among other commonly prescribed brands. While it is important to be aware of the risks of taking combined contraceptives, it is equally important that these risks be considered with appropriate perspective.
What is the link between combined contraceptive medication and blood clots?
The hormone oestrogen is a known clotting factor in women. While men are statistically more likely to develop a blood clot, women are more at risk during pregnancy due to the increased level of oestrogen responsible for sustaining the pregnancy.
Combined contraceptive medications work by overriding your menstrual cycle and preventing ovulation (the release of an egg from the ovaries). They contain synthetic forms of oestrogen and progesterone: the oestrogen prevents ovulation from occurring, while the progesterone works by thickening the mucus lining around the uterus to stop sperm from entering and encountering an egg, and thinning the uterus lining to prevent a fertilised egg from implanting. Combined contraceptive brands such as Cilest contain a slightly higher amount of oestrogen than Rigevidon and Microgynon, which helps prevent the occurrence of breakthrough bleeding.
It is the oestrogen in the combined pill which is linked to the increased risk of blood clots, a risk which varies according to the particular type of synthetic, its concentration and any other risk factors the patient may have. In a year of taking combined contraceptive medication, the risk of developing a blood clot ranges from 5 to 12 women in 10,000 compared to 2 in 10,000 women not taking the medication being at risk. To give some perspective, it is of note that the risk of developing a blood clot during pregnancy is far greater than the risk associated with taking combined contraceptives.
Is it safe to take combined contraceptive medication?
While it is important to be aware of the risks when taking combined contraceptives, they remain a safe and reliable form of contraception. Alongside being 99% effective against pregnancy when used correctly, combined contraceptives are used to help alleviate a number of other health issues, such as heavy periods, painful cramps and acne.
Of course, every person is different and reacts to medications in different ways, particularly hormonal ones. A doctor will be able to advise you on which type of pill is right for you, or on whether you should be taking combined contraceptives at all. To reduce the risk of serious health complications, a doctor will take into account the following factors before prescribing combined contraceptive medication:
- Whether you are a smoker and older than 35
- Whether you are overweight or have a high BMI
- Whether you have high blood pressure
- Whether you have diabetes
- Whether you have had a blood clot, heart attack or a stroke in the past
- Whether you have a family history of blood clots, heart attack or a stroke
- Any other medication you are currently taking
While combined contraceptive medication can be taken with caution if you have one of the above risk factors, your doctor is unlikely to prescribe it if you have two or more. Although the risk of a blood clot is minimal, it is important to recognise the signs and act accordingly. You should seek immediate medical help if you experience any of the following:
- Sudden shortness of breath
- Difficulty breathing, seeing or speaking
- A feeling of pressure in the chest
- Swelling, pain or tenderness in your legs or arms
Women experiencing minor symptoms such as weight gain, heavy bleeds or mood swings may choose to try a different contraceptive medication. You can read about the different types of oral contraceptives and possible side effects on the Dr Felix website.
How is the risk factor measured?
Before being approved for use in practice, new medications undergo a series of trials to ensure their safety for a wide group of patients. When approved for practice, the medication's safety, side effects, and effectiveness continue to be monitored in what is known as ‘phase four’ trials, as the public contains more variation than is found during clinical trials. If a patient experiences side effects of a particular medication, they should let their GP know as there is a process for these to be reported.
While combined contraceptives are no longer considered new, the UK’s latest large-scale study of the link to blood clots was published in May 2015. The case-controlled study used two large GP databases, and confirmed that the risks of taking combined contraceptives remain minimal and that doctors should continue to prescribe them. For anyone interested in reading the full review, it was published in the peer-reviewed British Medical Journal as an open-access article.
NHS – Is my contraceptive pill safe? https://www.nhs.uk/news/medication/combined-contraceptive-pills-increase-risk-of-blood-clots/
NHS – Media hype blood clot risk of contraception: https://www.nhs.uk/news/heart-and-lungs/media-hype-blood-clot-risk-of-birth-control-pills/
NHS – Clinical trials: https://www.nhs.uk/conditions/clinical-trials/
BMJ – use of combined oral contraceptives and risk of venous thromboembolism: https://www.bmj.com/content/350/bmj.h2135