What Are the Side Effects of the Pill?

I can be difficult for your GP to know if you will experience side effects from the contraceptive pill before you have started taking it. Many women don’t experience any unwanted side effects while on the pill, but you may need to try a few different ones before finding the one that works best for you.
Every woman reacts differently to each pill, and different contraceptive pills may cause different side effects.

Possible side effects of the pill include:

• Changes in mood, mood swings and depression
• breast pain or tenderness, breast enlargement
• fungal infections and cystitis
• migraine or headache
• feeling nauseous and vomiting
• stomach problems and diarrhoea
• irregular bleeding
• skin rash and acne
• hair loss
• changes in body weight
• high or low blood pressure levels
• low libido

If you do experience side effects from the pill, your symptoms will often improve after the first 3 months as your hormones adapt to the medication.

As every contraceptive pill has slightly different side effects, you should always read the patient leaflet of the medication you are taking. There is a range of other, rare side effects that may occur in a small number of women.

While most side effects of the pill are temporary and harmless, there are some symptoms you should not ignore.

You should speak to your doctor immediately if you experience:

• painful swelling in your leg
• jaundice (yellowing of eyes or skin)
• sudden pain in the chest
• a sudden cough
• difficulty breathing
• a migraine for the first time
• unusually severe migraine
• numbness in any body part
• blurred vision or impaired vision
• difficulties with your speech
• fainting and dizziness or seizures
• swelling of the face, tongue or throat
• dimpling of your skin
• lumps in your breast
• changes in your nipples
• unusual discharge or bleeding
• pain during sex or pelvic pain
• severe abdominal pain

These side effects are rare to very rare but they can indicate a serious condition such as an allergic reaction, a problem with your liver or cancer. If you suffer from any abnormal side effects which bother you, you should always discuss them with a doctor.

Combined pills are traditionally taken with a 7 day break in between each pack. You can however have a shorter break eg 4 days, or no break at all and take packs back to back. Not taking a break from the pill between packs might increase your chances of breakthrough bleeding and bloating. Besides these, the chances of getting any other side effects won’t increase if you stop taking breaks between pills.

Contraceptive pills which contain oestrogen, such as combined pills, have been found to cause a slight increase in your risk of breast cancer and cervical cancer. The increased risk of breast and cervical cancer starts to fall back down again once you stop using the combined pill. Around 10 years after you stop taking the combined pill, your risk of breast and cervical cancer is no longer affected and is the same as for people who never took the combined pill.

At the same time, the combined pill reduces the chances of you getting ovarian cancer and cancer of the womb. The longer you take the combined pill for, the bigger the reduction in risk of ovarian and womb cancer. Studies suggest this ovarian and womb cancer risk reduction effect even remains for decades after you stop taking the pill.
The link between the mini-pill and cancer is less clear, but so far the evidence suggests the risks for breast cancer might be similar to those for the combined pill. However the mini pill has been shown to offer some protection against cancer of the womb. 

But what does this mean for me?

If you have a family history of cancer or know that you have a high risk of cancer (for example because you have already had it), your GP may not recommend that you take a pill which contains oestrogen.

Taking a contraceptive pill which contains oestrogen also slightly increases your risk of thrombosis (blood clots), so it’s not recommended that women who have a high risk of stroke or thrombosis take contraceptive pills that contain oestrogen, such as combined pills. If you are over 35 and you are a smoker, your GP will recommend that you take a mini-pill instead. The same applies if you are very overweight or have a family history of blood clots.

A study about the pill and thrombosis conducted by the MHRA showed that 1 in 10,000 women who do not take a contraceptive pill develop thrombosis. Out of 10,000 women who take the pill Yasmin for example, 2 - 4 will develop thrombosis. 

However, the data for pregnant women showed that pregnancy increases your risk of thrombosis far more than the pill. Pregnant women are up to 5 times more likely to have a blood clot compared to women who are not pregnant.