What are the side effects of the contraceptive pill?

Dr Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 15 Feb 2022

Like many medications, the contraceptive pill has some side effects. Most of these will get better as you get used to taking a pill every day. Not everyone experiences side effects. The majority of women use the pill without any problems as a safe, effective and reliable method of contraception.

Depending on the type of pill you take, you might get different kinds of side effects. The combined pill contains both an oestrogen and progestogen hormone. The progesterone only pill (mini pill) contains a synthetic progestogen. Oestrogen can cause a separate set of side effects to progestogen, like nausea.

Remember that the pill does not protect you against sexually transmitted infections (STIs). Only condoms can protect you against STIs by providing a physical barrier. If you get symptoms like vaginal discharge, a burning sensation when you pee or blisters on your vagina, you may need to do an STI test.

2 women walking in the city talking about the side effects and their contraceptive pills

Common birth control side effects

Common side effects of birth control pills can happen in up to 1 in 10 women. They are usually temporary and will disappear as your body gets used to the change in hormone levels.

Some common side effects include:

  • headache
  • feeling sick
  • acne
  • breast tenderness
  • low mood or mood changes
  • weight gain

You might also get some vaginal bleeding or breakthrough bleeding when taking the combined pill for the first time. Your body needs to adjust to the changing hormone levels, so the bleeding should disappear within a few weeks.

Even if a side effect is listed as common, this does not mean you have to keep taking the pill if the side effects are concerning you. If you are experiencing a side effect that is persistent and does not resolve after a few weeks, speak to your doctor. There are plenty of birth control options, so you do not need to keep taking one if it causes you problems.

Uncommon and rare birth control side effects

Uncommon side effects can happen in up to 1 in 100 women. This means if 200 women took the pill, only 1 or 2 of them would experience these side effects.

Uncommon side effects of birth control pills include:

  • being sick
  • diarrhoea
  • feeling tired
  • migraine
  • decreased sex drive
  • rash
  • fluid retention

You might get different side effects depending on whether you're taking the combined pill or the mini pill. You can find more information on specific side effects from the patient information leaflet in your pack.

Rare side effects happen in less than 1 in 1000 women. These include:

  • vaginal discharge
  • weight loss
  • hives (a type of rash)
  • an allergic reaction
  • blood clot

Taking the combined pill has a small risk of blood clots associated with it.

Are there any health risks associated with taking the pill?

The 2 main health risks associated with the birth control pill are blood clots and breast cancer, but these are rare.

Pregnant women and women who have just given birth are also at a high risk of blood clots.

Your natural risk of getting a blood clot is about 2 in 10,000. This is if you’re not taking any hormonal contraceptive and are not pregnant.

If you take a combined contraceptive pill, your risk increases to about 5 to 7 in 10,000 women. As you can see, that’s still a small risk!

Before you start to take a contraceptive pill, your doctor will assess your general health to check if you are at a higher risk of getting a blood clot. This includes checking if you:

  • are overweight
  • smoke
  • are over 35
  • recently gave birth
  • have a family history of blood clots
  • need to be off your feet for some time, like after an operation

If you’re at a higher risk of blood clots, your doctor may advise you to take the mini pill instead. The mini pill carries a much smaller risk of blood clots. You need to have your blood pressure and weight checked to see if the pill is suitable for you. If you have uncontrolled high blood pressure or heart disease, you may not be able to take the combined pill.

You will also need to check your blood pressure and weight every year if you are taking the pill continuously.

Taking the pill has an increased risk of developing breast cancer, but this risk is still relatively small. It’s rare to get breast cancer if you’re under 40, though you may be more likely to develop it if you have a family history of breast cancer.

The risk of breast cancer in women who have never taken a contraceptive pill is about 16 in 10,000. This means 16 women in 10,000 will get breast cancer before they turn 35.

For women who take the pill for at least 5 years in their early twenties, around 18 out of 10,000 will get breast cancer by the time they are 35. This means this risk only slightly increases when you are taking the pill.

It’s always important to check your breasts for any changes whether or not you’re taking any hormonal contraceptive.

Is it safe to use the contraceptive pill long term?

The pill has been used for a few decades as an effective method of contraception, which means there’s a lot of evidence for the safety of the pill. The pill is also used to manage other women's health conditions, like irregular periods or endometriosis.

While you can get side effects when using the pill, there are also long term benefits. The pill is one of the most reliable forms of contraception that does not interrupt having sex. It can make your periods lighter and less painful, and help to ease premenstrual symptoms (PMS).

The risk of blood clots goes down after the first year of taking the pill. While the risk of some cancers remains, bear in mind that your natural risk of breast cancer increases as you get older. Some studies show that if you take the contraceptive pill for more than 5 years, your risk of other cancers, like ovarian cancer, drops by 50%.

If you start to take other medications, always check with your doctor or pharmacist if you can take these with your contraceptive pill. Some medications can interact with the pill and give you side effects. This includes prescription items and over the counter products.

If the oral contraceptive pill is causing you side effects, you can try a different method of birth control. Hormonal birth control includes patches, implants or vaginal rings. You can also choose to have a non-hormonal implant called the copper IUD (intrauterine device). Speak to your doctor or sexual health clinic for more information.

Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 15 Feb 2022

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