Woman and doctor

Combined hormonal contraception

Combined hormonal methods contain both an estrogen and a progestogen, and are available as pills, a patch applied to the skin, or vaginal rings. This page provides a general overview of the potential benefits and risks associated with the different types of combined hormonal contraceptives. In addition, information particular to each type of contraceptive is provided. It is important to also refer to the individual product information.

You should not use any type of combined hormonal contraceptive (the combined oral contraceptive pill ('the Pill), patch or vaginal ring) if you have, or have had in the past, some medical conditions. These are outlined in the patient information leaflets for combined hormonal contraception, and your prescriber will discuss these with you. If you have any concerns about the suitability of your contraception, talk to your prescriber.

The combined oral contraceptive pill (‘the Pill’)

Combined oral contraception (COC or ‘the Pill’) contains an estrogen and a progestogen hormone. The most commonly used estrogen in COC is ethinylestradiol, a synthetic form of estrogen. The strength of combined contraceptives is based on the amount of estrogen that they contain. Most pills contain between 20 micrograms and 35 micrograms ethinylestradiol. Low-strength preparations contain 20 micrograms ethinylestradiol and standard-strength preparations generally contain 30 micrograms or 40 micrograms ethinylestradiol. 

The British National Formulary contains a list of currently marketed products. Some of the more recently approved products contain a different estrogen called estradiol.

A number of different types of progestogens (a synthetic form of progesterone) are used in combined oral contraceptives and include:

  • levonorgestrel
  • norethisterone
  • desogestrel
  • gestodene
  • norgestimate
  • drospirenone
  • nomegestrol acetae
  • dienogest.

Most COC come as packs of 21 pills, where one pill is taken daily for 3 weeks, followed by a break of 7 days. A few types of COC come as packs of 28 pills, where one ‘active’ pill is taken every day for 3 weeks, followed by an ‘inactive’ or placebo pill (which does not contain any hormones) for seven days. Other preparations that combine different numbers of active and placebo pills are also becoming available.

COCs can be started at any point during the menstrual cycle provided there is no risk of existing pregnancy. If COC is not started during the first 5 days of bleeding, additional contraception such as condoms should also be used for the first 7 days of taking contraceptive pill. See our section on when to start taking combined oral contraceptives, and refer to the information leaflet that accompanies each medicine.

As well as preventing unwanted pregnancies, combined oral contraceptives can reduce menstrual blood loss and relieve painful menstruation, and may help with premenstrual symptoms in some women. Long-term use of combined oral contraceptives is also associated with a reduction in the incidence of ovarian cancer (see below) and endometrial cancer.

DSU article: Combined oral contraceptives: prevention of ovarian cancer – April 2008

The contraceptive patch (Evra)▼

In the UK, one contraceptive patch is currently available, called Evra - a combined hormonal contraceptive that contains both an estrogen (ethinylestradiol) and progestogen (norelgestromin). It is applied to certain areas of the skin once weekly for 3 weeks, as recommended in the patient information leaflet, followed by a seven day patch-free interval. The patch should be checked daily to ensure that it has not fallen off.

The contraceptive vaginal ring (NuvaRing)

In the UK, one contraceptive vaginal ring, called NuvaRing is currently available. NuvaRing is a combined hormonal method that contains estrogen (ethinylestradiol) and progestogen (etonogestrel). The ring is inserted into the vagina for 3 weeks, followed by a 7-day ring-free interval.

The contraceptive vaginal ring has not yet been used very widely and so its safety compared with other forms of combined contraceptives is not known for rare and long-term effects. As a result therefore the information describing potential adverse risks in the patient information leaflet for NuvaRing are based largely on combined oral contraceptives, which are considered to be most applicable to the use of NuvaRing.

Key safety information for combined hormonal contraceptives

All combined contraceptives increase the risk of thromboembolism (potentially dangerous blood clots which can develop within blood vessels). If blood clots develop in veins it is called venous thromboembolism, or VTE; if they develop in arteries it is called arterial thromboembolism, or ATE.

If a blood clot:

  • develops in the leg it can cause a deep vein thrombosis (DVT). 
  • travels to the lung it can cause a pulmonary embolism (PE)
  • travels to the heart it can cause a heart attack
  • travels to the brain it can cause a stroke

The overall risk of a blood clot is small, but clots can be serious and may, in very rare cases, even be fatal. 

It is very important that you recognise when you might be at greater risk of a blood clot, what signs and symptoms you need to look out for, and what action you need to take.

In which situations is the risk of a blood clot highest?

  • in the first year of use
  • if you are very overweight
  • if you are older than 35 years
  • if you have a family member who has had a blood clot at a relatively young age (eg, below 50)
  • if you have given birth in the previous few weeks 

There is also some evidence that the risk is higher if you are restarting use after a break of 4 weeks or more.

If you smoke and are over 35 years old you are strongly advised to stop smoking or use a different method of contraception. See the patient leaflet for a more complete list.

Seek medical attention immediately if you experience any of the following symptoms:

  • Severe pain or swelling in either of your legs that may be accompanied by tenderness, warmth or changes in the skin colour such as turning pale, red or blue.  You may be experiencing a deep vein thrombosis.
  • Sudden unexplained breathlessness or rapid breathing; severe pain in the chest which may increase with deep breathing; sudden cough without an obvious cause (which may bring up blood);.  You may be experiencing a serious complication of deep vein thrombosis called a pulmonary embolism. This occurs if the blood clot travels from the leg to the lung.
  • Chest pain, often acute, but sometimes just discomfort, pressure, heaviness, upper body discomfort radiating to the back, jaw, throat, arm together with a feeling of fullness associated with indigestion or choking, sweating, nausea, vomiting or dizziness. You may be experiencing a heart attack.
  • Face, arm or leg weakness or numbness, especially on one side of the body; trouble speaking or understanding; sudden confusion; sudden loss of vision or blurred vision; severe headache/migraine that is worse than normal.  You may be experiencing a stroke.

Watch out for symptoms of a blood clot, especially if you have:

  • just had an operation
  • been off your feet for a long time (eg, because of an injury or illness, or if your leg is in a cast)
  • had a long a long journey (eg, air travel for more than about 4 hours).

Remember to tell your doctor, nurse or surgeon that you are taking combined hormonal contraception if you:

  • are due to or have had surgery
  • are in any situation when a healthcare professional asks you if you are taking any medications.

For further information, please read the patient information leaflet that accompanies your combined hormonal contraception or talk to your prescriber.

A Europe-wide review of the combined hormonal contraceptives finalised in November 2013. The review looked in particular at the risk of blood clots associated with the use of combined contraceptives. It concluded that:

  • the risk of blood clots with all CHCs is small
  • there is good evidence that the risk of VTE may vary between products depending on the progestogen
  • CHCs that contain levonorgestrel, norethisterone or norgestimate have the lowest  risk of VTE
  • the benefits of any CHC far outweigh the risk of serious side effects
  • prescribers and women should be aware of the major risk factors for blood clots and of the key signs and symptoms
The European review recommended that all women should know more about the risk of blood clots, what conditions increase their natural risk of a clot, the signs and symptoms of a blood clot and when they need to tell a healthcare professional that they are using a combined contraceptive (see above). 

No important new information on the safety of combined contraceptives has become available since this issue was last reviewed. The risk of blood clots with combined contraceptives has been known about for many years, and much information has already been provided to prescribers and women.

Further information: 

Statement from the European Medicines Agency, January 2014

Prescriber checklist and information for women in annexes 2, 3, and 4 of this letter to healthcare professionalsPDF file (opens in new window) (149Kb), January 2014

Risk of VTE with combined oral contraception (‘the Pill’)

Large studies done over many years have provided good evidence that risk of a blood clot may vary between the combined contraceptives depending on the type of progestogen hormone it contains. Combined contraceptives considered to have a lower risk of blood clots contain the progestogens levonorgestrel, norgestimate or norethisterone.

However, it is important to remember that the overall risk of having a blood clot is small in most women for whom a combined contraceptive is appropriate.

The person who prescribes your contraceptive should discuss the benefits and risks of the combined contraceptives with you. In particular they should highlight the small risk of blood clots, the conditions that increase the risk of blood clots and go through some of the key signs and symptoms to be aware of (see above). 

If your circumstances mean you have a naturally higher risk of a blood clot—eg, you are older than about 35 years, greatly overweight or have a family history of a blood clot your doctor may advise you to start on one of the lower risk products. If you have more than one of these conditions your contraceptive provider may consider that you should use a different method of contraception.

If you have any concerns about your contraception, you should discuss them with your contraceptive provider but keep taking your contraceptive pill until you have done so. If you stop taking your pill, you will need to use another method of contraception, such as a condom, as you otherwise risk becoming pregnant.

Risk of VTE with the contraceptive patch (Evra) and contraceptive vaginal ring (NuvaRing)

As with the combined oral contraceptive pill, the contraceptive patch Evra and contraceptive vaginal ring NuvaRing slightly increase the chance of VTE/thrombosis.

The risk of VTE in users of these products may be slightly increased compared with the risk in users of COCs that contain ethinylestradiol plus levonorgestrel, norethisterone, or norgestimate

Risk of arterial thromboembolism (ATE) with all combined hormonal contraceptives

All combined hormonal contraceptives slightly increase the risk of ATE.  However, there is no evidence that this risk differs between products.

Cervical cancer

Long-term use (ie, for more than 5 years) of COC is associated with a small increased risk of cervical cancer. However, the overall risk of cervical cancer is very low, whether hormonal contraception is used or not, and the level of risk in COC users decreases to the risk seen in those who have never used COC within 10 years of stopping use. If a woman currently has cervical cancer or has had it in the past, or has unexplained vaginal bleeding, she should not use any type of hormonal contraception.

DSU article: Hormonal contraceptives: cervical cancer: April 2008

MHRA Information and Q&A document for women who use hormonal contraceptives: April 2008PDF file (opens in new window) (34Kb)

Regular cervical screenings are essential for checking the health of the cervix and can reduce the risk of developing cervical cancer. Women of certain ages are automatically invited by the NHS for a free cervical screening. It is important that all women attend when invited for smear tests.

NHS fact sheet: Cervical screening: the facts (external link)

NHS cervical screening Q&A (external link)

In addition, a routine vaccination against human papillomavirus (HPV), a sexually transmitted infection that can cause cervical cancer, has been introduced for girls aged 12–13 years in the UK since 2008.

MHRA information webpage on the HPV vaccine

Breast cancer

There is a slightly increased risk of having breast cancer diagnosed in women who are currently using combined hormonal contraceptives, including combined oral contraceptives (ie, the Pill) compared to those who do not use them. If a woman has breast cancer or has had it in the past she should not use any type of combined hormonal contraceptive.

Breast cancer is rare in women under 40 years, and in studies has been found slightly more often in women who take combined hormonal contraceptives (these include combined oral contraceptives, Evra Patch or NuvaRing).

A meta-analysis of 54 epidemiological studies reported that there is a slightly increased risk of having breast cancer diagnosed in women who are currently using any COC, the Pill), compared to those who are not.

It is possible that this small increase in risk has been observed in these studies because women taking combined hormonal contraceptives are examined more often, which increases the chance of any breast tumours being detected.

Once COCs are stopped, the excess risk of breast cancer starts to fall; ten years after stopping, the risk falls to the level seen in women who have never used COCs.

MHRA publication: oral contraceptives and breast cancer – March 1998

It is important for a woman to regularly examine their breasts and to tell their contraceptive provider if a close female relative has or has ever had breast cancer.

When to start taking combined oral contraceptives

In May 2011, the product information for all COC marketed in the UK was updated with new advice on when in the menstrual cycle the Pill can be started. The information is consistent with clinical guidance, and is as follows:

When to start taking the Pill

If you and your GP are sure that you are not pregnant, you can start taking COC on any day of the menstrual cycle.

  • If you start COC during your period (ie, during the first five days of bleeding), you will be protected from pregnancy immediately.
  • If you start COC at any other time, you must use an additional, non-hormone based method of contraception such as condoms, as well as the Pill, for the first 7 days.

See below for full guidance from the Family Planning Association on using combined hormonal contraceptive pills:

Family Planning Association (FPA): Guide to the combined hormonal contraceptive pill (external link)

The new advice follows a review of the evidence underlying the current guidance, which was performed by the MHRA and the Commission on Human Medicines (CHM). The updates will ensure that the advice is consistent between different brands of the Pill, and is in line with clinical guidelines.


Page last modified: 07 March 2014