There are some risks associated with using the combined contraceptive pill (the pill). However, these risks are not common. For most women, the benefits of the pill outweigh the risks.
Blood clots
The oestrogen in the pill may cause your blood to clot more readily. If a blood clot develops, it could cause a deep vein thrombosis (clot in your leg), pulmonary embolus (clot in your lung), stroke or heart attack.
The risk of getting a blood clot is very small, but your doctor will check if you have certain risk factors that make you more vulnerable before prescribing the pill. The pill can be taken with caution if you have one of the risk factors below, but should not be taken if you have two or more risk factors.
Risk factors include:
- being over 35 years old
- being a smoker or having quit smoking in the last year
- being very overweight (the pill should not be taken if your BMI is over 40)
- having migraines (you should not take the pill if you have severe or regular migraine attacks, especially if you get aura or a warning sign before an attack)
- having high blood pressure
- having had a blood clot or stroke in the past
- having a close relative who had a blood clot when they were younger than 45
- being immobile for a long time, for example in a wheelchair or with a leg in plaster
Cancer
Research is ongoing into the link between breast cancer and the pill. Research suggests that users of all types of hormonal contraception have a slightly higher chance of being diagnosed with breast cancer compared with women who do not use them. However, 10 years after you stop taking the pill, your risk of breast cancer goes back to normal.
Research has also suggested a link between the pill and the risk of developing cervical cancer and a very rare form of liver cancer.
However, the pill does offer some protection against developing cancers of the endometrium (lining of the womb), ovaries and colon.
For more information, see the Cancer Research UK factsheet on the contraceptive pill and cancer risk.
