Combined hormonal contraceptives contain two types of hormone, an oestrogen and a progestogen. Historically this type of contraceptive was a tablet, commonly referred to as "the pill", but now a skin patch which releases oestrogen and progestogen into the body through the skin and a vaginal ring that releases a set amount of oestrogen and progestogen into the bloodstream each day are also available.
How do they work?
Combined hormonal contraceptives act by mimicking your natural oestrogen and progesterone in order to prevent the release of an egg from your ovaries (ovulation). The hormones supplied in the combined contraceptive pill, patch or ring influence certain areas of the brain (the pituitary gland and the hypothalamus) preventing the production of gonadotrophins (follicle stimulating hormone [FSH] and luteinising hormone [LH]). Gonadotrophins are specialised hormones, which are necessary for an egg to ripen and mature and then be released from the ovaries. Combined hormonal contraceptives prevent ovulation by blocking this hormonal process.
Combined hormonal contraceptives also cause the lining of the womb (the endometrium) to become thinner, which prevents the likelihood of an egg implanting (attaching itself to the lining of the womb) successfully. In addition, the cervical mucus becomes thicker making it more difficult for sperm to move through it and reach an egg.
What are the advantages of combined hormonal contraception?
- It is one of the most reliable and convenient methods of contraception and is totally reversible
- It can help to relieve premenstrual symptoms and often makes periods lighter and less painful
- It reduces the risk of developing ovarian cysts and fibroids
- It can protect against cancer of the lining of the womb (endometrial cancer) and ovarian cancer
- It reduces the severity of endometriosis if this is already present
What are the disadvantages of combined hormonal contraception?
- It must be taken correctly to ensure reliability
- There can be minor side effects such as headaches, weight changes, nausea, breast tenderness and breakthrough bleeding (bleeding between periods). If these side effects do not stop after a few months, changing the type of pill or from a pill to a patch or ring, or vice versa, may help
- In some women, blood pressure may rise and they may be advised not to take the pill or use the patch or ring
- Combined hormonal contraceptives offer no protection against sexually transmitted diseases, including HIV
What are the risks of taking combined hormonal contraceptives?
Serious side effects, such as a blood clot that could cause a stroke or heart attack, are rare.
Combined hormonal contraceptives are available only on prescription to ensure that they are only given to those women for whom they are suitable. The risks are greater for some women and medical advice should be given to those women who may not be able to take the pill or use the patch or ring - these include women with diabetes or high blood pressure, women who are significantly overweight, women who smoke and women who have a close family history of stroke or heart attacks at an early age. The risks associated with using combined hormonal contraceptives increase with age and so a woman over 35 who also smokes may be advised against taking the pill or using the patch or ring.
There is research to show that women taking the combined contraceptive pill may be at an increased risk of breast cancer; this risk is thought to disappear gradually over the 10 years after stopping the pill.
Some research has linked the pill with an increased risk of cervical cancer but other research has not proved this. It is thought that this increased risk may be explained by the fact that women taking the pill who practise unprotected sex (ie, do not use condoms) are at a greater risk of sexually transmitted diseases.
There is no evidence to date to suggest that using the combined hormonal contraceptive patch or ring is, in any aspect, safer than taking the combined hormonal contraceptive pill.
What are the different types of combined pill?
There are two main types of combined pill available: fixed dose and phasic preparations.
Fixed dose preparations are monophasic; they contain the same fixed dose combination of oestrogen and progestogen in every tablet in the packet. Most of these pills are available as 21-day packs where pills are taken for 21 days continuously followed by a seven-day pill-free break when bleeding will take place. During the seven-day break the pill is still effective and you remain protected against pregnancy. However, the next pack must be started on the eighth day to ensure continuing protection.
Examples of 21-day fixed dose pills include Acondro®, Aidulan®, Alenvona®, Bimizza®, Brevinor®, Cilest®, Cilique®, Cimizt®, Cleosensa®, Dretine®, Elevin®, Femodene®, Femodette®, Gedarel®, Katya®, Lestramyl®, Levest®, Lizinna®, Loestrin®, Lucette®, Maexeni®, Marvelon®, Mercilon®, Microgynon® 30, Millinette®, Munalea®, Norimin®, Norinyl-1®, Ovranette®, Rigevidon®, Sunya®, Yacella®, Yasmin® and Yiznell®.
Everyday (ED) or 28-day packs of fixed dose pills are also available. These are taken continuously for 28 days without a break between packs and are useful for those women who may forget to start taking a new pack after a break. The packs usually contain 21 hormone pills and seven pills which are inactive (24 hormone pills and four inactive pills for Daylette®, Eloine® and Zoely®); the pills must be taken in the correct order.
Examples of ED or 28-day fixed dose pills include Eloine®, Femodene® ED, Microgynon® 30 ED and Zoely®.
Phasic preparations reduce the overall hormone intake by giving different levels of hormones at different times of the month. The tablets must be taken in their correct order. The 21-day pill packs have 21 hormone pills that need to be taken continuously for 21 days followed by a pill-free break of seven days.
Examples of 21-day phasic pills include Logynon®, Synphase®, Triadene® and TriRegol® (called triphasic pills as they have three different hormone levels).
Everyday (ED) or 28-day phasic pills are also available. These are taken continuously for 28 days without a break between packs and are useful for those women who may forget to start taking a new pack after a break. The packs contain active hormone pills and inactive pills. The pills must be taken in the correct order.
Examples of ED or 28-day phasic pills include Logynon® ED, a triphasic pill that has 21 active hormone pills and 7 inactive pills and Qlaira®, a pill with four hormone levels that has 26 active pills and 2 inactive pills. Qlaira® is also effective in reducing heavy menstrual bleeding.
Contraceptive pills containing co-cyprindiol (eg, Dianette®) are another type of pill, which may be prescribed for women with severe acne that cannot be controlled by antibiotics, or for women with mild hirsutism (excess body hair). It is not normally prescribed solely for contraceptive purposes although when prescribed for women with acne it also acts as a contraceptive.
Using the contraceptive patch
The contraceptive patch releases oestrogen and a progestogen into the body through the skin at a steady rate over seven days. Currently, there is only one contraceptive patch available, Evra®. One patch should be applied to clean, dry, hairless skin on the buttock, abdomen, upper outer arm or upper torso on the same day each week for three weeks followed by a patch-free week during which bleeding will occur, similar to the pill-free week associated with oral contraceptives. You are protected against pregnancy during the seven-day break, providing you apply a new patch on the eighth day as instructed.
Using the contraceptive vaginal ring
The vaginal ring releases oestrogen and a progestogen into the bloodstream at a steady rate over 21 days. NuvaRing® is currently the only vaginal ring available. One ring should be compressed and inserted into the vagina until it feels comfortable. It should then be left in place for three weeks before removing on the same day of the week that it was inserted. This should be followed by a one-week interval with no ring during which bleeding will occur. A new ring should then be inserted on the same day of the week as the previous ring. You are protected against pregnancy during the seven-day break, providing you insert a new ring on the eighth day as instructed.
What can stop the pill, patch or ring working effectively and so cause a risk of pregnancy?
- Missing one or more pills or forgetting to apply a new patch or insert a new ring on the designated day
- Being unaware that a patch is no longer attached properly - if a patch is even partly detached for 24 hours or more contraceptive protection may be lost
- Being unaware that a ring has been expelled - if a ring is out of the vagina for more than three hours contraceptive protection may be lost
- Starting the new pack too late, ie, after the eighth day of the patch-, pill- or ring-free break (or after the third day for Qlaira®)
- Vomiting or severe diarrhoea may stop the pill from working, particularly if they occur within three hours of taking the pill.
- Some medicines given on prescription, eg, some antibiotics, may interfere with the effectiveness of the pill, patch or ring. You should always tell your doctor or dentist that you are taking a combined hormonal contraceptive if they are going to prescribe you another type of treatment
- Always check the instructions given with your particular combined hormonal contraceptive or ask your doctor or nurse if you think there is any reason why your pill, patch or ring might not work properly
What to do if you miss a pill?
If you miss one combined pill (excluding Qlaira® and Zoely®) or if you start a new pack a day late, you should take the missed pill immediately and continue taking the rest of the pack as normal. No extra contraceptive precautions are required.
If you miss two or more pills consecutively during the first three weeks of a pack or if you start a pack more than one day late, you should take a pill straight away and continue taking the rest of the pack as normal. Additional contraceptive precautions should be used for the next seven days.
If the pills were missed in the first week of the pack and unprotected sex has taken place you should talk to your doctor or another healthcare professional about emergency contraception.
If the pills were missed in the third week of the pack, you should continue taking the pills from that pack and start the next pack immediately without a break.
If you are more than 12 hours late taking Qlaira® or Zoely®, you should check the instructions in the pack or talk to a healthcare professional as additional contraception may be needed.
Are any regular checks necessary?
The first prescription for a combined hormonal contraceptive will probably be for three months supply and if appropriate you will usually then be prescribed six months supply at a time. Blood pressure should always be checked when the prescription is renewed. Other screening tests such as regular cervical smears may also be offered - these are not offered because you are taking a combined hormonal contraceptive but because you are sexually active and may therefore require additional tests.
Further information available from:
British Pregnancy Advisory Service (BPAS)
20 Timothy's Bridge Road
Stratford Enterprise Park
Stratford-upon-Avon CV37 9BF
Tel: 0345 365 5050
Helpline: 03457 30 40 30
FPA (Sexual Health Charity)
23-28 Penn Street
London N1 5DL
Tel: 020 7608 5240
For young people under 25 years:
Brook Advisory Centres
Helpline: 0808 802 1234 (Monday to Friday, 11am-3pm)
Fact sheet provided by MIMS
Date last reviewed: June 2014