Contraceptive Pill Side Effects

Dr Clair Grainger

Medically reviewed by

Dr Clair Grainger

Last reviewed: 07 Oct 2019

What can change when you start taking the pill?

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

The contraceptive pill is one of the most common forms of contraception among women today. It can be up to 99% effective in preventing pregnancy when used correctly. But, as with most forms of hormonal contraceptive, there are also some possible side effects it’s good to be aware of.

The two types of contraceptive pills are the combined contraceptive pill and the mini pill. They are made up of lab-made forms of two hormones that your body naturally produces. The combined pill is made up of oestrogen and progestogen, while the mini pill contains only progestogen.

Women generally react differently to hormones, so the side effects one woman may have when using the contraceptive pill, will not be exactly the same as another. Side effects of being on the pill can also be positive as well as negative.

What are the most common side effects of the contraceptive pill?

Irregular bleeding

Both types of contraceptive pill work mainly by stopping ovulation (the monthly release of an egg from your ovaries). When you take the pill you do not have periods but will likely experience some bleeding.

With the combined pill, you will usually bleed during your pill-free week but bleeding can be more unpredictable on the mini pill (which is taken continuously without a break).

It’s common to experience ‘breakthrough bleeding’ (which is when you bleed or spot when this is not expected) when using the pill, especially with the mini pill. This usually happens in the first three months of taking a particular type of pill, and should get better after that.

If you start to have heavy bleeding, or bleeding that lasts for more than a week, you should contact your doctor who may suggest you change to a different pill or form of contraception.

If you have unexpected or problematic bleeding that lasts more than 3 months after starting the pill, talk to your doctor to make sure there are no other underlying causes for this.

Feeling sick (nausea)

Feeling sick is more common within the first two to three months of using the contraceptive pill, and often goes away after that. It can help to take the pill with food, and preferably in the evening before bed. If you keep feeling sick, a pill with a lower amount of oestrogen may help.

Short-term weight gain

Some women may worry about weight gain when starting the contraceptive pill. There’s no proven link between taking the pill and long-term weight gain however oestrogen and progesterone hormones can cause water retention and bloating.

You can manage any changes in your weight while on the pill, by avoiding salty foods to help reduce water retention in your body. You can also restrict your food intake and exercise regularly to maintain a healthy weight.

Breast tenderness or swelling

The hormones in the contraceptive pill can cause changes in breast tissue which may cause pain and swelling. This should improve after the first few months of using the pill, as your body adjusts to it.

If you do notice any lumps or abnormal swelling at any point or have breast pain lasting more than three months, you should contact your GP.


Women using the mini pill may notice spots or acne on their skin during the first few months. If it becomes distressing, you should contact your doctor to discuss other contraceptive options.

The combined contraceptive pill, on the other hand, commonly helps to clear acne, usually within a few months.

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What are less common side effects of the contraceptive pill?

Mood changes

Some studies have suggested a link between using the combined pill and having mood changes or feeling depressed. This is likely to be caused by the hormone changes in your body after you start using the pill. This can be helped by changing the type of progesterone in your combined pill. Although mood changes are listed as a potential side effect of the mini pill by manufacturers this has not been backed up in further studies.

If you notice frequent changes in your mood or any symptoms of feeling depressed, you should talk to your GP.


Although it’s a less common side effect, the hormones in contraceptive pills can increase your chances of getting mild headaches, or migraines, within the first few months of using the pill.

If you have migraines already your GP may discuss using progesterone-only or non-hormonal methods of contraception as the combined pill increases the risk of stroke in certain patients with migraine.

If you develop migraines after starting the combined pill you should stop the pill, use condoms, and see your GP about alternative contraception.

You can manage mild headaches by drinking plenty of water, avoiding stress where possible, and taking the pill at the same time everyday. If you still experience mild headaches after a few months, you should contact your GP about changing to a different pill or another type of contraception.

Reduced sex drive

Loss of sex drive is an uncommon side effect of the contraceptive pill. It is more common if you’re taking the mini pill. If you continue to experience less interest in having sex after a few months of using the pill, you should visit your GP who may suggest you change pills, or to a non-hormonal contraceptive method. They may also chat to you about any other possible reasons for your lower sex drive.

Are there any other risks of taking the contraceptive pill?

Apart from side effects, there are some other risks of being on the pill you should consider. A doctor can help you decide if these things may affect you, and whether the benefits of using the pill might outweigh the risks.

  • Using the combined pill has been linked with a small increased risk of breast cancer and cervical cancer. It is unclear if there is a link between the mini pill and breast cancer.
  • Oestrogen in the combined pill can increase your risk of developing blood clots, which can cause thrombosis (blood clots in your leg), stroke, or heart attack
  • The combined pill can also raise blood pressure in some women, especially if they have other risk factors for this like smoking, diabetes, or being overweight

Taking the contraceptive pill with other medications

Some medicines can make the contraceptive pill less effective in preventing pregnancy. It is important to tell your doctor about all short- and long-term medicines you are currently taking, so you can both decide if the contraceptive pill is right for you. These medications include:

  • antibiotics like rifampicin and rifabutin used to treat tuberculosis (TB)
  • HIV medication
  • epilepsy medicines like carbamazepine, oxcarbazepine, phenytoin, phenobarbital, primidone, and topiramate
  • herbal medicines like St John’s wort
  • laxatives and weight-loss medications (these may affect the absorption of your pill in some cases)
  • acne medication (Roaccutane)

The contraceptive pill can also make some medicines you’re taking less effective, like epilepsy medications. Always check the patient information label and chat to your doctor or pharmacist for further advice.

How to find the right contraceptive pill for you

A doctor can advise you on the best contraceptive pill to use. They will ask you about your medical history and current lifestyle and will advise which contraception is safest for you. Apart from potential side effects, you’ll also need to think about other factors, some of which include:

  • Age If you are over 35 and smoke, a doctor may suggest you try the mini pill, or other birth-control options, because there is a higher risk of developing blood clots when taking contraception containing oestrogen
  • Being overweight If you’re overweight a doctor may advise against taking pills containing oestrogen as this increases your risk of blood clots and high blood pressure
  • Taking medications If you take long-term drugs for conditions like HIV or epilepsy they can reduce the effectiveness of contraceptive pills
  • Medical conditions The contraceptive pill may not be suitable if you have a history of illnesses like diabetes, high blood pressure, liver disease, breast cancer, blood clots, migraines, heart disease, or have recently given birth
  • Family history If you have a close relative that has suffered from blood clots at a young age you may be offered contraception which does not contain oestrogen

The best contraceptive pill for you may well be a balance of benefits, side effects, and risks. Some people find this combination with the first pill they take. For others there can be some ‘trial and error’ before finding something that feels right.

The Lowdown is a good place to read about other women’s experiences with different pills.

Alternatives to the contraceptive pill

If you or your doctor think the pill might not be right for you, there are other effective contraceptive options you can consider. Online tools and resources like the ones offered by Brook and the NHS are also handy for thinking through your options.

Hormonal contraceptives

The contraceptive patch and the contraceptive vaginal ring have similar side effects to the combined pill and the same risks including a higher risk of blood clots.

Common side effects of the progesterone-only contraceptive injection include headaches, irregular periods, weight gain and abdominal discomfort.

The progesterone-only contraceptive implant’s very common side effects can include irregular periods, acne, breast tenderness and headaches.

The IUS (intrauterine system) can cause irregular, heavier, or missed periods initially. Very common side effects include breast tenderness, acne and headaches.

The IUD (intrauterine device; copper coil)

Some women have reported heavy periods when using the IUD. There is also a risk of infection during the first three weeks of having the device put in place.

Barrier methods

Condoms are typically made of latex rubber which some people are allergic to. If this is the case, you can also get condoms made of non-latex materials. Condoms are typically less effective at preventing pregnancy than hormonal or long acting contraception.

You could also use a contraceptive diaphragm which is made from silicone.

Medically reviewed by:
Dr Clair Grainger

Dr Clair Grainger studied at The University of Edinburgh from 2004 to 2009. She's worked in hospitals throughout Edinburgh and London before completing her GP training in North Middlesex Hospital in 2017.

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Last reviewed: 07 Oct 2019

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