Combined oral contraceptive pill

The combined oral contraceptive pill (usually just called the pill) contains both oestrogen and progestogen. When taken correctly these pills are 99% effective in preventing pregnancy.

How the combined pill works

It works by:

  • preventing an egg being produced (ovulation)
  • thickening the cervical mucus (which stops sperm getting through)
  • altering the lining of the uterus so that if an egg does get fertilised it is less likely to implant and grow.

Types of combined pill

There are 2 main types of combined pill:

  • monophasic – contains equal doses of oestrogen and progestogen
  • triphasic – contains differing levels of oestrogen and progestogen, which mimics a normal menstrual cycle.

The available contraceptive pills in New Zealand change from time to time. Often pills will have different brand names but contain the same active ingredients. Ask your doctor or pharmacist if you have questions about which pills are funded.

Who can’t take the combined pill

Your doctor may not prescribe the pill for you if you have:

  • focal migraines with an aura or that cause numbness or weakness to parts of the body
  • hypertension (high blood pressure)
  • a personal or family history of blood clots
  • liver disease, history of or current breast cancer, or other medical conditions.

Smoking or being overweight are also risk factors which may mean the combined pill is not right for you.

If you can’t take the combined pill, the progesterone-only pill might be a good option for you.

How to take the combined pill

Both monophasic and triphasic pills are taken for 21 days followed by a 7-day break. Most pill brands have inactive pills for you to take during those 7 days, so you stay in the habit of taking a pill each day. At some time in the 7-day break you will have bleeding like a normal period.

Starting the pill on day 1 or 2 of your period provides instant protection. If you start at any other time in your cycle, you will not be protected until you have taken 7 pills. So during this time you should use another form of contraception (eg, condoms) or not have sex.

Things to avoid while you’re on the combined pill

While taking the pill you need to be aware that some other medicines can affect how well the pill works. It is best to avoid:

  • St John’s Wort
  • enzyme-inducing drugs, for example anti-epileptics, rifampicin, griseofulvin and antiretrovirals
  • laxatives and antimotility drugs.

Talk to your doctor before taking any of these medicines while you are on the pill.

Grapefruit juice can also affect absorption of the pill, so do not drink it at the same time of day as you take your pill.

Side effects of the combined pill

Not everyone will get side effects from the pill, and they can vary from very mild to annoying. Some side effects are:

  • breast tenderness
  • headaches
  • mood changes
  • skin changes.

Break-through bleeding can occur in the first few months (light bleeding or spotting during the 21 days of active pills). This usually settles down as your body gets used to the pill cycle.

Missed pills

If you miss a pill you should use other contraception (eg, condoms) or not have sex for the next 7 days.

  • The most risky time to miss a pill is during the first week after the 7-day break. If you miss a pill in this time and have had sex, you have a higher risk of getting pregnant and may want to consider the emergency contraceptive pill.
  • If you miss a pill during days 7 to 14, you are less likely to get pregnant. Seek help if you are worried about missing a pill.
  • If you miss a pill in the third week, you are unlikely to get pregnant, but you must skip the 7-day break and go straight to the first active pill in the next packet
  • If you miss more than 1 pill, consult a health practitioner.

Call Healthline 0800 611 116 if you are unsure what you should do.

Stopping the pill

You can stop taking the pill at any time during a cycle, and you will probably then have some bleeding like a period. Your menstrual cycle will go back to how it was before you took the pill, although it might take a few months to become regular again.

If you are changing pill brands, skip the 7-day break and go straight to the first active pill in the new packet.

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