The combined oral contraceptive is a potent drug which can also have unwanted side-effects. The following is a general outline of the side-effects and risks of the combined oral contraceptive. However, in case of conflicting information the product information of the preparation you have been prescribed always takes precedence. It is therefore important to read the pack insert carefully and follow any advice given by your doctor.

Side-effects

When you start taking the pill you may experience nausea, vomiting or headaches. However, these symptoms usually disappear after a few cycles.

Bleeding abnormalities (spotting or bleeding between periods, irregular cycles) may also occur at the beginning and usually disappear after a few months. If you experience more prolonged bleeding abnormalities or do not bleed in the pill-free interval you should consult your doctor.

The estrogen component of the hormonal contraceptives can lead to accumulation of fluid in the tissues. This can cause weight gain or breast tenderness, for example.

Patchy yellowish-brown discoloration of the skin may occur, particularly on the face. In this case prolonged exposure to sunlight and UV radiation should be avoided.

Serious side-effects of the pill are very rare. Certain symptoms can point to serious side-effects and may make it necessary to stop taking the pill immediately.

The pill and thrombosis

A thrombosis is a blood clot which can cause blockage of a blood vessel. A thrombosis can occur in the veins (e.g. deep vein thrombosis (DVT) of the legs). Parts of the blood clot can become detached and travel with the bloodstream to the lung where they can obstruct pulmonary blood vessels and cause pulmonary embolism. Deep vein thrombosis can also occur in people not using hormonal contraceptives, e.g. during pregnancy. The risk of developing deep vein thrombosis is slightly greater in pill users than in women not taking the pill but is not as high as during pregnancy.

Blood clots can also form in the blood vessels of the heart (heart attack) or the brain (stroke). The occurrence of blood clots in other organs (e.g. liver or stomach) is even less common.

There are a number of personal risk factors for the occurrence of thrombosis. Attention must be paid to these when the pill is prescribed.

The risk of vascular disease generally increases with increasing age. It is particularly high in smokers. If you want to take the pill you should stop smoking, particularly if you are older than 35. Otherwise a different method of contraception should be used.

The pill and cancer

There are numerous studies on the connection between the pill and breast cancer. The results of these studies are not consistent. Some studies show no connection between use of the pill and breast cancer. In other studies breast cancer was found slightly more often in pill users than in women of the same age not taking the pill. However, ten years after discontinuing the pill this difference has disappeared. It is not known whether it is the pill that causes the difference. It is possible that breast cancer is simply overlooked less often in women taking the pill. Women who take the pill generally go to the doctor more often than women not on the pill. Therefore the chance of discovering breast cancer in pill users is greater. As breast cancer is usually detected earlier in pill users it is smaller and is less likely to have developed metastases than in women not on the pill. This substantially increases the chances of cure.

Cervical cancer has been found slightly more often in pill users. This is probably not a result of taking the pill. Other factors are regarded as being the cause of cervical cancer, particularly certain viral infections. Women who take the pill are usually more sexually active and thus have an increased risk of infection. The risk of infection is particularly high in women with frequently changing sexual partners. In addition, pill users usually have regular cancer screening which leads to more frequent and earlier diagnosis of cervical cancer. It is therefore not known whether the cancer actually occurs more often or is only missed less often.

For pill users and non-users alike the same applies: cervical cancer can be detected and effectively treated while it is still in the preliminary stage. Regular cancer screening is therefore important.

In extremely rare cases liver tumors can occur in pill users.