The mini pill contains just progestogen making it suitable for women who are sensitive to oestrogen. It has a reputation for being well tolerated by the majority of women who use it but there is a possibility of side effects, like any prescription medication. For the complete list, please see below.

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Cerazette mini pill package
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Cerazette

  • Almost 100% effectiveness
  • Suitable if you are sensitive to oestrogen
  • Can be used whilst breastfeeding
Noriday oral contraceptive pill
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Noriday

  • Can alleviate cramps
  • No oestrogen used
  • Highly tolerable
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Cerelle

  • 99% effective contraception
  • Doesn't contain oestrogen
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Mini Pill Overview

The mini pill can be used by a wide range of women for a number of reasons besides contraceptive cover. It can reduce menstrual cramps, regulate the time of the month and lessen symptoms of PMS on top of offering protection against unwanted pregnancy.

With no added oestrogen, the mini pill is an option for women who are sensitive to that particular hormone. In addition, women who are breastfeeding, women over 35 years old, women who smoke and women who suffer from migraines, can use it.

Whilst the mini pill is extremely tolerable for most, it can pose the risk of side effects, like any prescription medication. It is unlikely that you will experience anything awry when using the mini pill but it's important to gather all information just in case.

Below we have an in-depth review of the side effects you may experience whilst taking the mini pill. If you would like further information on how to take the mini pill and where to obtain it, you can visit our dedicated mini pill page.

Mini pill side effects overview

On this page we will look at the common side effects through to rare side effects of the mini pill following these frequency guidelines:

  • Common – Likely to affect from 100 to 1,000 women in every 10,000
  • Uncommon – Likely to affect from 10 to 100 women in every 10,000
  • Rare – Likely to affect from 1 to 10 women in every 10,000

This includes the 3-hour mini pill and the 12-hour mini pill. In the UK, it's important to establish which mini pill you have as missing a contraceptive pill can alter the effectiveness. Noriday and Micronor are 3-hour pills meaning you must take each daily pill within a 3-hour timeframe every day. This doesn't leave much room for error. Cerelle and Cerazette are both 12-hour mini pills so the timeframe is more manageable and similar to the combined pill. The Cerazette mini pill is, therefore, one of the most popular types in the UK.

When starting a new pill, the body needs to alter to the influx of hormones. This means that side effects, whilst still unlikely, may appear during the first few months. These are generally manageable.

Doctors tend to recommend a course of 3 months initially. If during this time, side effects are disruptive and consistent, contact your doctor about the next steps.

Common side effects Uncommon side effects Rare side effects
  • Mood changes
  • Low libido and sex drive
  • Nausea
  • Headaches
  • Acne
  • Breast tenderness or pain
  • Irregular or no periods
  • Vaginal infection
  • Vomiting
  • Hair loss
  • Painful periods
  • Ovarian cysts
  • Increased fatigue
  • Rashes and hives
  • Erythema nodosum (painful blue-red skin lumps)
  • Vaginal discharge
  • Breast discharge or leakage

Like all prescription medications, side effects are listed but may not occur. If side effects persist past the initial three months, visit your doctor to talk about your contraceptive options.

Common side effects of mini pill

Many of the side effects of taking the mini pill are relatively minor. The table outlines some of these less serious effects as defined in the electronic Medicines Compendium (eMC). Each side effect is also classified in terms of how likely you are to experience them.

For common side effects, it is often advised to manage them with other medication, although do read the patient leaflet to ensure that the mini pill will maintain its efficacy. Monitor these side effects and if they are causing any distress, contact your doctor.

Irregular bleeding as a side effect of the mini pill

Irregular bleeding of the mini pill is classed as a common side effect which will pass over time. This is often light enough to be referred to as "spotting". It may require a thin sanitary pad until your body has gotten used to the hormones. For heavier bleeding, a tampon or pad can be used.

If bleeding, regardless of the amount and frequency, persists then it's important to contact your doctor.

If you have unexplained irregular bleeding that isn't your period before you begin the mini pill (or any other contraception), it is essential to visit your doctor to determine why it is happening.

When you first start taking contraception, like other long-term medications, it can take time for your body to adjust. This is completely normal during the first few months and these symptoms should ease over time.

How to prevent the risk of side effects

To minimise the risk of side effects, you should disclose all relevant information to your doctor during your initial consultation.

1) Advise you doctor of allergies

It is possible to have an allergy to one of the ingredients contained in the mini pill. You should advise your doctor in particular if you are allergic to aspirin, a yellow food colouring called tartrazine, progestins or any other medications.

2) Advise your doctor of all medications your taking

The mini pill can interact with other medications that can impact on its effectiveness and also potentially increase your risk of side effects. You should advise your doctor of all prescription medications and non-prescription medications you are taking during your consultation. You should also mention any vitamins, nutritional supplements and herbal products such as St John's Wort.

In particular, you need to make sure to advise them if you are taking Rifadin (rigampin), Dilantin (phenytoin), Tegretol (carbamazepine), Luminal or Solfotom (phenobarbital), as these can all interact with progesterone only pills.

3) Advise your doctor of previous medical history

Because of the potential for the mini pill to increase your risk of breast cancer and liver disease, it's important to advise your doctor if:

  • You've had undiagnosed breast lumps
  • You've had breast cancer
  • You've had liver tumours or liver disease
  • You have diabetes
  • You've had a stroke or have coronary heart disease

One of the common side effects with the mini pill is irregular menstrual bleeding. It is important to let your doctor know if you've experienced problems with heavy bleeding, irregular bleeding or have had vaginal bleeding between periods in the past.

4) Advise your doctor if you are or could be pregnant

It is not advised to take progesterone only contraceptives while pregnant. If you think you could be pregnant, you should advise your doctor. If you become pregnant while taking the mini pill, you should stop taking it and speak with your doctor, as it can put you at an increased risk of an ectopic pregnancy.

Uncommon side effects of mini pill

There are some slight additional risks associated with taking the mini pill. It is again important to be aware of these and their potential signs and symptoms.

For uncommon side effects such as a vaginal infection, painful periods and fatigue, there are other medications you can try that can lessen the severity. However, these should be discussed with your doctor and always thoroughly read the label/patient leaflet before use.

If you are vomiting on the mini pill, this may make the contraceptive less effective, especially if it is soon after you have taken the contraception.

Rare side effects of mini pill

Any side effects in the table classed as "rare" are more serious effects of the medication and you should stop taking the mini pill. Consult your doctor who will advise you whether to keep taking this mini pill or change to another form of contraception. If you have stopped taking the mini pill, this will reduce its effectiveness so use barrier contraception such as condoms for the foreseeable future.

Rare side effects such as a rash or hives can indicate an allergic reaction to the medication. Other symptoms of an allergic reaction include swelling to the face, neck and throat. If you are experiencing an allergic reaction, it's important to seek medical assistance immediately. Stop taking the medication until further notice and doctor's approval.

Cerazette and angioedema

Angioedema is a swelling in the skin's deeper layers. It can be caused by an allergic reaction to the mini pill in rare cases. If you experience symptoms of angioedema such as a swelling of your face, tongue or pharynx or difficulties breathing or swallowing, you should seek medical help right away.

The mini pill and blood clots (Thrombosis)

It is believed that women who take the pill are at a slightly higher risk of developing blood clots (medically known as thrombosis). This could be deep venous thrombosis (in the blood vessels) or pulmonary embolism (in the lungs). However, this is lower than the risk during pregnancy and it is also thought to be lower with progesterone only pills compared to combined pills containing oestrogen.

Similar to other pills, it's thought that progesterone only pills can also slightly increase your chance of breast cancer, although this is not conclusive. Whilst the risk of breast cancer increases with age, the below table highlights the potential additional risks of the pill according to recent research. It is thought that the mini pill and the combined pill have similar results.

The below table details the women who have never taken the contraceptive pill and have been diagnosed with breast cancer, versus the women who have:

Category Never on the pill On the pill for 5 years
  • Stopped pill at 20
  • Stopped pill at 30
  • Stopped pill at 40
  • 4 out of 10,000
  • 44 out of 10,000
  • 160 out of 10,000
  • 5 out of 10,000
  • 49 out of 10,000
  • 180 out of 10,000

It is difficult to determine whether it is the contraceptive pill that is one factor of a breast cancer diagnosis as age and hereditary factors can play a major part.

It's important to check your breasts frequently for lumps or abnormalities, and report to your doctor if you notice anything different.

The mini pill and ectopic pregnancies

If you become pregnant while taking the mini pill, you are at an increased risk of the pregnancy being an ectopic pregnancy, compared to other forms of contraception. An ectopic pregnancy is one that is outside the womb. If you experience any sudden or abnormal pain or bleeding, you should contact your doctor.

Mini pill and breastfeeding

Mini pills can be used whilst breastfeeding. Research has shown that it does not pass through the body into breast milk. It is also a great alternative for women who have difficulties tolerating oestrogen-based pills.

Always inform your doctor if you wish to use the mini pill, and other medications, if you are breastfeeding.

Risk factors that provoke side effects of the mini pill

Certain factors can put you at an increased risk of experiencing side effects of the mini pill, or in the worst case scenario, be dangerous to your health. To minimise and prevent these risks, it's important to fully advise your doctor during the consultation process if any of the below apply. You should NOT take the mini pill if you have:

  • Ever had breast cancer or have undiagnosed lumps
  • Any unexplained or excessive vaginal bleeding
  • Ever had liver cancer or jaundice
  • Ever had, or have a family history of, blood clots (Thrombosis)
  • Diabetes
  • Ever suffer from epilepsy
  • Tuberculosis
  • High blood pressure
  • Had chloasma or any brown skin patches

Medications that interact with the mini pill

The following medications may interact negatively with the mini pill. This includes provoking side effects, and/or making the pill less effective:

  • Epilepsy
  • Tuberculosis
  • HIV infection
  • Hepatitis C
  • High blood pressure
  • St John's Wort
  • Some bacterial and fungal infections

What if I experience side effects of the mini pill?

The mini pill will be offered to you initially in a 3-month supply. In the future, you can continue with a 3-month supply or 6-month supply depending on your doctor's recommendation.

It's worth noting that you may find you experience side effects in the first 3 months but it is advised to continue taking the contraceptive unless these symptoms are detrimental to your quality of life.

Light to mild side effects tend to disappear after the initial 3 months and are manageable during this time.

If the side effects are affecting your day-to-day life and/or persist after 3 months, then contact your doctor. It is unlucky that the mini pill will be doing any lasting damage but if it is, there are many contraceptive options out there to try.

Dr Hilary Jones Independent Medical Adviser

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