How does the patch work?

The contraceptive patch is a small, beige patch that sticks onto your skin. It releases copies of two natural hormones – oestrogen and progesterone – to prevent pregnancy.

The patch releases these hormones at a steady rate, getting them into your bloodstream through your skin and changing the hormone levels in your body.

While it can affect many of your body’s organs, the effects that make it an excellent contraceptive are:

  • it stops you from producing an egg (ovulating) – no egg means there’s nothing to fertilise

  • it thickens the cervical mucus – this stops sperm travelling from the vagina into the womb (uterus)

  • it thins the lining of the womb so a fertilised egg can’t implant there – this is a back-up measure as most people won’t produce an egg at all

How the patch affects the body

The patch hormones travel all over the body in the bloodstream. If it’s used correctly, it:

  • stops the pituitary gland in the brain from releasing the hormones that trigger ovulation each month, so no egg is released and therefore there’s nothing to fertilise

  • thickens cervical mucus so sperm can’t get through

  • thins the lining of the uterus so an egg can’t implant

  • helps reduce acne

  • can increase breast tenderness

  • slightly increases the risk of breast cancer

  • reduces the risk of cancer of the lining of the womb

How the patch affects your ovaries and womb

During ovulation, the cervical mucus is slippery so it’s easier for sperm to enter the womb. At the same time the lining of the uterus is thicker, so it’s easier for an egg to implant.

The hormones in the patch change both the womb and ovaries. No egg is released, the mucus is thicker, and the lining of the uterus is thinner.

In the UK there is, for now, just one type of contraceptive patch available. It's called Evra.

  • size: 5cm by 5cm

  • ingredients: 6 milligrams norelgestromin (progestogen) and 600 micrograms of ethinyl estradiol (oestrogen)

  • release rate: an average of 203 micrograms of norelgestromin and 33.9 micrograms of estradiol every 24 hours

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