Combined oral contraceptive pill

Also known as 'the pill'

Easy-to-read medicine information about the combined oral contraceptive pill (COC) – what is it, how is it given and possible side effects.

Type of medicine Examples
  • Contraception (prevents pregnancy)
  • A combination of the hormones oestrogen and progesterone
  • Also known as "the pill'.
  • Ava 20®
  • Ava 30®
  • Brevinor®
  • Brevinor-1®
  • Levlen ED®
  • Loette®
  • Marvelon®
  • Mercilon®
  • Microgynon 20®
  • Microgynon 30®
  • Microgynon 50®
  • Monofeme®
  • Norimin®
  • Yasmin®
  • Yaz®

What is the combined oral contraceptive pill?

The combined oral contraceptive (COC) pill is a form of contraception for women, to prevent pregnancy. The COC pill contains a combination of two hormones, oestrogen and progesterone

  • The COC pill prevents pregnancy by stopping ovulation (eggs being produced and released from the ovary).
  • It is also used to treat heavy menstrual bleeding or heavy periods (also called menorrhagia). It works by making the lining of the uterus thinner and in this way reduces the heaviness of the period.
  • There are a variety of brands and strengths of COC pills available in New Zealand, which contain a different combination of oestrogen and progesterone. Your doctor will assess the best combination for you. If you experience side effects, you may need to try a few different types, before you find one that is suitable for you.      

How well does the COC pill work?

  • The COC pill is one of the more reliable forms of contraception.
  • It is usually 92% effective, which means that it prevents a pregnancy in 92 out of 100 women who use the COC pill each year; eight women out of 100 women who use the COC pill will get pregnant each year.
  • If used perfectly (taken correctly), the COC pill is 99% effective in preventing pregnancy.
  • To ensure that the COC pill works best, it is important to take it correctly, which means remembering to take it everyday, whether you have sex on that day or not. It is also important to know that if you are sick (vomiting) soon after taking your daily pill, then it may not be absorbed and may not work. See below for more information.


  • The usual dose of the COC pill is one tablet once a day.
  • The COC pill pack usually contains both hormone (active) and non-hormone (inactive) pills.
  • Usually the active pill is taken for 21 days and the inactive pill for 7 days, but some women take the hormone pill continuously (no-period option) or take only the hormone pills for some months and every few months take the inactive pills to have a period.
  • Discuss the various options with your doctor, or nurse to find the option that suits you best. 
  • Always take the COC pill exactly as your doctor or nurse has told you. The pharmacy label on your medicine will tell you how to take it and any special instructions.

How to take the COC pill

  • It is best to take your tablet at about the same time each day.
  • You can take the pill with or without food.

'Seven day rule' and missed doses

Missed pills

  • If you miss a dose, the effectiveness of the COC pill may be affected and you may be at risk of becoming pregnant. 
  • If you forget to take a pill, take it as soon as you remember, and take the next one at the normal time (even if this means taking 2 pills together). 
  • If you miss 2 or more pills (especially from the first 7 in a packet), you may not be protected. Take the active pill as soon as you remember and take the next one at the normal time. In addition, you must either abstain from sex or use an additional method of contraception such as a condom for the next 7 days. If these 7 days run beyond the end of the active (hormone) tablets in the packet, the next packet should be started at once, omitting the pill-free interval (or, in the case of everyday (ED) pills, omitting the 7 inactive tablets). 
  • If you are unsure about what to do if you have missed one or more pills, contact your doctor, nurse, pharmacist or call HealthLine 0800 611 116 for advice.  

Diarrhoea and vomiting

  • Vomiting and persistent, severe diarrhoea can interfere with the effectiveness of the COC pill.
  • If vomiting occurs within 2 hours of taking the pill, take another pill as soon as possible.
  • If the vomiting is persistent and continues or the diarrhoea is severe, lasting more than 24 hours, you will need to take additional precautions during and for 7 days after recovery.
  • If the vomiting and diarrhoea occurs during the last 7 active (hormone) tablets, the next pill-free interval or the inactive pills should be omitted.
  • If you are unsure about what to do if you have vomiting and diarrhoea, contact your doctor, nurse, pharmacist or call HealthLine 0800 611 116 for advice.

Who cannot take the COC pill

Most women can take the pill. If you are healthy, do not smoke, are not overweight and have no medical reasons for you not to take the pill, you can take it until your menopause. However, in some women the COC pill is unsuitable. You should not use the COC pill if:

  • you have had a heart attack, stroke or blood clot in legs or lungs
  • your parents or brothers or sisters have had a blood clot in their legs or lungs
  • you are over 35 and smoke
  • you are overweight
  • you have gallstones
  • you have breast cancer
  • you have diabetes with complications
  • you are about to have major surgery
  • you have migraines
  • you are pregnant
  • you are taking certain medications, over-the-counter preparations or herbal remedies.

Your doctor or nurse will be able to work out whether the COC pill is safe for you individually.

Possible side effects

Like all medicines, the combined oral contraceptive pill can cause side effects, although not everyone gets them. 

Side effects What should I do?
  • Breast tenderness
  • Headaches
  • Mood changes
  • Skin changes
  • These may go away with time. If severe and persistent, tell your doctor or nurse 
  • Break through bleeding (bleeding that occurs intermittently) or spotting   
  • This may go away with time. If persistent, tell your doctor or nurse 
  • Severe stomach pain, signs of liver problems (dark coloured urine, yellow skin and eyes)
  • Severe headache or loss of vision or fainting or numbness.
  • Tell your doctor immediately or ring HealthLine 0800 611 116
  • Signs of blood clots such as swelling, pain or change in colour in one or both legs, or chest pain, difficulty breathing or shortness of breath. Read more about hormonal contraceptives and blood clots.
  •  Tell your doctor immediately or ring HealthLine 0800 611 116 


A few medications and herbal supplements may interact with the COC pill and lessen its effectiveness, so always check with your doctor or pharmacist before starting any new medication.

Learn more

The following is further reading that gives you more information about the combined oral contraceptive pill: 

Learn more about the COC pill:
Combined oral contraceptive pill NZ Family Planning
Combined oral contraceptive pill Ministry of Health, NZ
Learn more about the risks of the COC pill:
Hormonal Contraceptives and Blood Clots Medsafe
Oral contraceptives and blood clots Ministry of Health, NZ 

Medsafe datasheets on specific brands 
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 22 Jan 2019