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10 side effects of the combined pill

side effects of the combined pill

The combined contraceptive pill is a type of birth control medication that contains two hormones, progestogen and oestrogen. These hormones work by preventing you from ovulating (releasing an egg), thicken the mucus in your cervix which makes it hard for sperm to pass through and a it thins the lining of the womb, making it harder for an egg to implant, all of which stops you from getting pregnant.

Combined contraception pill brand names include Yasmin, Cilique, Mercilon, Qlaira and Logynon. Generally, you’ll take one pill a day for 21 days, followed by a break of four or seven days. You will also need annual blood pressure, height and weight (BMI) checks to make sure everything is fine.

The contraceptive pill is very safe and side effects are rare, however, it works slightly differently for each person. 

In this article, we’ll take a look at what the side effects of the combined pill are and what they might mean for you.

Spotting between periods

You might experience spotting between periods on the combined contraceptive pill. Don’t worry, this is usually normal, although it’s not always clear what causes it.

Spotting between periods is more likely with continuous or extended-cycle regimens than the traditional 28-day schedule, and it's more common in the first few months of use as your body becomes used to the hormones in the pill. It may also be due to the thinning of the lining in your uterus.

You might be more likely to experience spotting between periods while on the pill when you:

  • Miss a pill
  • Start a new medication, such as antibiotics
  • Become ill with diarrhoea or vomiting, as it can stop you from absorbing the medication correctly

Smokers are also more likely to experience breakthrough bleeding than non-smokers.

You’ll generally find that bleeding slows or stops over time. It might help you to track your bleeding in a diary or calendar, so you can see if it decreases. 

If spotting lasts for seven days in a row, or if it becomes heavy, you should speak to a GP, as you could have an infection or another condition that is interfering with the pill. Your doctor might recommend you try a different method of contraception.

It’s important to remember that spotting does not mean the pill isn’t working, and you should continue to take it every day at the same time to make sure it works properly. 

Mood changes

Some people do find that the pill affects their mood. However, this is incredibly rare.

A study by Harvard University found that out of 658 women, 107 (16.3%) said that they’d experienced birth control mood swings. 81 (12.3%) said their mood had actually improved on the pill. 470 women (71.4%) saw no change. The survey also found that women with a history of depression were more likely to experience mood changes on the pill.

If you have a history of depression or anxiety, you should speak to your doctor about this before starting the contraceptive pill, and watch your mood closely after you start.

Birth control mood swings are very rare and the majority of women will not experience any problems. If you’re concerned, you should speak to your doctor. They might recommend that you change to a different pill or to a different type of contraceptive altogether.

Again, you shouldn’t stop taking your pill outright without talking to your doctor first. 

Weight gain and the pill

Does the contraceptive pill cause weight gain? This is a very common concern for people who are just about to start the combined contraceptive pill, or have been on it for a short while. 

The good news is that there’s no clear link between weight gain and the pill. It’s very rare to gain weight on the pill, and any weight gain you notice is probably just due to water retention, and not because of an increase in body fat.

Every pill comes with its own set of side effects, and these affect each person differently. If you are concerned about weight gain and the pill, speak to your doctor.


Nausea is a common but usually mild side effect of the combined contraceptive pill, particularly in the first few days and weeks of taking it. It’s generally due to your body struggling to get used to the additional progestogen and oestrogen.

You might find that taking your pill with food reduces the symptoms of birth control nausea. Anti-nausea medication might also help, but you should discuss any additional medication with your doctor before you start taking it.

Birth control nausea can be very uncomfortable but usually passes once your body becomes used to the pill. If you continue to experience it after a couple of months, speak to your doctor about an alternative method of contraception.

Breast pain on the pill

Breast pain is a side effect of the combined contraceptive pill, as is breast growth. This can be concerning, as you might begin to worry that you have another, more serious condition, such as breast cancer.

Short-term breast pain on the pill can happen, but it does not mean there’s anything to worry about. However, if the pain continues and does not fade after a few weeks, or if you’ve noticed a lasting change in the size or shape of your breast, you must speak to your doctor.

Breast cancer and the pill

The pill can increase the risk of breast cancer over time. There is no guarantee that the contraceptive pill will increase your risk of breast cancer, and the link between cancer and the contraceptive pill is unclear.

However, if you have a family history of certain cancers, such as breast, ovarian, or prostate cancer, the combined pill could increase your risk. You should discuss your medical history with your doctor before starting the pill, as there may be a better solution for you. Learn more about the link between breast cancer and the combined contraceptive pill.

Breast pain on the pill does not necessarily mean you have breast cancer, so don’t panic. If the pain continues, talk to your doctor.

Migraines and the pill

If you experience migraines with aura, you’ll be advised against taking the combined contraceptive pill, or other combined contraceptives like the patch and the ring. The problem with migraines and the combined pill is that taking the combined pill can increase your risk of ischaemic stroke. And ischaemic stroke is associated with migraines, particularly those with aura.

If you’ve had migraines with aura, your clinician might suggest you try the progestogen-only pill or another type of contraception.

Missed periods

Does the contraceptive pill stop periods? Not always. Taking birth control might result in very light or missed periods, and some forms of contraception can indeed stop you from having periods altogether. 

It’s important to know that you can get pregnant on the pill. However, it is very unlikely, and the pill is more than 99% effective when taken correctly. 

Fewer than 1 in 100 women using the contraceptive pill correctly will get pregnant within a year, compared to 9 women in 100 who do not always use it correctly.

No form of contraception, except for abstinence, is 100% effective. If you’re sexually active and think you might be pregnant, or if you’re concerned about your missed periods, you should speak to your doctor as soon as possible.

Decreased libido

It is possible to experience a reduced or fluctuating libido while on the combined contraceptive pill.

The female hormones in contraceptive pills can impact the levels of testosterone in our bodies, which is what triggers the urge for sex. When testosterone is low, so is your sex drive.

The pill might also trigger vaginal dryness, which can make sex uncomfortable and cause you to avoid it.

Most women report zero changes to their sex drive while on the pill. As we’re all different, and there’s no baseline for what can be considered a ‘normal’ sex drive, it’s hard to tell how contraception could affect you.

A reduction in libido can also be caused by environmental or relationship factors, so the pill might not be to blame.

If you think your pill could be the cause of your low libido and it’s affecting your life, speak to your clinicians.

Again, don’t stop taking your pill without consulting a clinician first, as this could lead to pregnancy. Learn more about how the combined contraceptive pill can impact your sex drive.

Vaginal discharge

Vaginal discharge is a substance produced by the body to keep the vagina moist and lubricated and to prevent infection. It often appears as a white or clear liquid/jelly in your underwear. Some amount of vaginal discharge is entirely normal and nothing to worry about.

The pill thickens your cervical fluid to prevent sperm from entering the uterus, which can, in turn, change the colour or texture of your discharge. You might find that it is whiter or thicker while on the pill.

Some change to your discharge while on the pill is perfectly normal. You should only be concerned if your discharge:

  • Smells fishy or like rotten meat
  • Is very thick and white, with a texture like cottage cheese 
  • Is green, yellow, brown or pink in colour 
  • Is frothy in texture 
  • Is much heavier than usual

If you’ve experienced any of the above, or if you’ve noticed sores, pelvic pain, vaginal bleeding, itching, or pain, then you should speak to your doctor, as this may be the result of an underlying problem, such as a sexually transmitted infection (STI).

Long-term side effects of the combined pill

Like any medication, the pill can have additional side effects when taken for an extended period. The long-term side effects of the combined contraceptive pill include:

  • Increased blood pressure
  • Increased risk of blood clots
  • Increased risk of breast cancer and cervical cancer

Your doctor should discuss your medical history with you prior to prescribing the pill. If they feel you’re at an increased risk of more serious side effects, they will discuss a different solution with you.

Read more about the long-term side effects of the contraceptive pill.

Side effects of the combined contraceptive pill are rare, and the pill is completely safe for most people.


The combined contraceptive pill is popular because it’s an easy, non-invasive, and highly effective birth control solution. There are many types available, so if one pill doesn’t work for you, you should ask your doctor if you can switch to another. You can get low-dose versions, like Leonore, which tend to cause less side effects.

It’s important to remember that you shouldn’t stop taking your pill cold turkey, as this could lead to unplanned pregnancy. If you’re concerned, you should talk to your doctor, as they are equipped with the right knowledge and training to find the best contraceptive pill or method for you.

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    Authors and editors

    Reviewed and updated by: Our clinical team Date reviewed: 15-05-2024