Hormonal contraception

Published by Bupa's Health Information Team, May 2010.

This factsheet is for women who are taking hormonal contraceptives, or who would like information about them.

Hormonal contraception is the most effective method of controlling fertility and preventing pregnancy. The effects of hormonal contraceptives are fully reversible once treatment is stopped. The most popular hormonal contraception is commonly known as the pill. Other methods include patches, injections, implants, intra-uterine system (IUS) and the progestogen-only pill (also known as the mini-pill) .

Why would I take hormonal contraception?

Nearly four million women in the UK use hormonal contraception as a convenient and effective way to control fertility and prevent pregnancy.

Hormonal contraception is also sometimes used to treat heavy periods and endometriosis and to relieve severe premenstrual symptoms.

Hormonal contraception doesn't protect against sexually transmitted diseases.

What are the main types of hormonal contraception?

There are a number of different types of hormonal contraception.

• Combined oral contraceptive (COC) pill. This is often just called the pill and contains two hormones - a progestogen and oestrogen. These are similar to the hormones that you produce in your ovaries.
• Progestogen-only pill (POP). This is sometimes called the mini-pill and can be taken by women who can't take the COC pill.
• Contraceptive patch and ring. Oestrogen and a progestogen can also be taken via an adhesive skin patch and as a vaginal ring.
• Long-acting injections. There are two main hormone injections that can provide long-lasting contraception for eight or 12 weeks. Both injections contain a progestogen.
• Implant. This is inserted under your skin. It releases a constant amount of a progestogen, giving contraception for up to three years.
• Intra-uterine system (IUS). This is a plastic T-shaped device that is placed in your womb (uterus). It releases progesterone and works for up to five years.

Emergency hormonal contraception

If you think your contraception may have failed, you can get emergency hormonal contraception (EHC) from your doctor, pharmacy, sexual health clinic or NHS walk-in centre. EHC is a tablet containing levonorgestrel, a type of progestogen.

Although often called the morning-after pill, it works for up to 72 hours after unprotected sex. But it's important to take it as early as possible for maximum effectiveness. EHC can prevent or delay an egg from being released or it can prevent fertilised eggs from implanting into the wall of the womb (uterus). This should stop you from getting pregnant. As an alternative to EHC, you can have an IUD fitted by your GP up to five days after unprotected sex. This also prevents an egg from fertilising or implanting in your womb.

How does hormonal contraception work?

Your monthly cycle is controlled by two main hormones, oestrogen and progesterone. Oestrogen levels rise after your period, causing an egg to develop and be released from your ovaries (ovulation). The lining of your womb thickens in preparation for a fertilised egg. After you have ovulated, progesterone helps the womb lining grow even thicker.

The egg travels down your fallopian tubes and, if you don't become pregnant, your body naturally absorbs the egg. The levels of oestrogen and progesterone in your body fall, and the womb lining comes away leaving your body as a menstrual period.

Hormonal contraceptives contain artificial (synthetic) versions of hormones. They mimic the action of oestrogen and progesterone on your body. When taken correctly, they interfere with your normal monthly cycle to prevent pregnancy.

Hormonal contraception works in three ways by:

• preventing your ovaries from releasing an egg
• thickening the mucus from your cervix (the neck of the womb) which makes it more difficult for sperm to enter your womb and fertilise the egg
• making the lining of your womb too thin for a fertilised egg to implant into

How to take hormonal contraception

Combined oral contraceptive (COC) pill

Most COCs are taken for 21 days. This is then followed by a break of seven days before the next course of 21 days. You will have a bleed when you stop taking tablets. This is called a withdrawal bleed.

Some brands, known as every day (ED) types, have 28 pills in the packet. They include seven inactive dummy pills, removing the need for a seven-day break. You just go from one packet to the next.

The COC pill is designed to be taken every day. If you miss taking a tablet, it can mean that you're at risk of becoming pregnant. Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

Progestogen-only pill (POP)

POPs are taken every day with no break. If you're taking the progestogen-only pill, the contraceptive effect may be lost only a few hours after a missed pill (or 12 hours for Cerazette). This means it's important to take your pill at the same time every day.

If you miss a pill and realise more than three hours later (or 12 hours later for Cerazette), you will need to use extra contraception, such as a condom, for the next two days to prevent pregnancy. Ask your doctor or nurse for advice.

Contraceptive patches

Contraceptive patches are worn every week for three weeks and then you have a week without wearing a patch. They are very sticky and should stay on even when you're showering, swimming or exercising. However, if the patch does come off, you will be protected against pregnancy if you replace it within 48 hours. If your patch has been off for longer than this, you will need to use another method of contraception for the next seven days. Ask your doctor or nurse for advice.

Contraceptive ring

Your doctor or nurse will show you how to insert a contraceptive ring into your vagina. With clean hands, you can insert and remove the ring with your fingers. You should keep the ring in your vagina for three weeks and then remove it. You will then have one week without the ring, before you insert another new one.

Long-acting injections

Long-acting hormonal contraception injections are given by your doctor or nurse. They are injected into one of your large muscles, such as your buttocks or upper arm. You will need to have the injection every eight or 12 weeks.

Implant

Progestogen implants are narrow flexible rods, about the size of a match stick. The rod is inserted under the skin of your upper arm using a local anaesthetic, so you won't feel any pain. Your nurse or doctor will put the implant in and will also remove it when it needs to come out. The implant can stay in for up to three years.

Intra-uterine system (IUS)

An IUS is a plastic frame that is placed in your womb (uterus) to prevent your eggs from reaching the sperm and being fertilised. Your doctor or nurse will put it in. This can be uncomfortable and sometime painful. It is often used for women who have had children. Speak to your doctor or nurse if you would like painkillers or local anaesthetic.

Side-effects of hormonal contraception

All hormonal contraceptives can have some side-effects, but these aren't common. For most women, the benefits of hormonal contraception outweigh the risks. Some of the main side-effects of hormonal contraception are listed below.

• The COC pill, patches and ring can increase your risk of developing blood clots in your veins (deep vein thrombosis or DVT). This risk is very small - lower than the risk of DVT that is naturally associated with being pregnant.
• The COC pill, patches and ring are also linked to a small increased risk of developing breast or cervical cancer. However, this is thought to return to normal within 10 years of stopping contraception. These contraceptives are thought to provide protection against ovarian cancer.
• POPs can cause headaches, mood swings and breast tenderness. They can also make you feel sick and cause your abdomen (tummy) to become bloated. These side-effects usually reduce after a few months.
• Depo-Provera, which is a progestogen-only contraceptive injection, can cause a temporary thinning of your bones. It can also cause weight gain. Women taking Depo-Provera may also find that it takes between six and 12 months for periods to return to normal or to conceive after stopping the injections.
• An intra-uterine system can sometimes cause an infection in the first 20 days after it is inserted. There is also a small possibility that the IUS can be pushed out of the uterus at the time of insertion.
• Many forms of hormonal contraception will cause changes in your menstrual pattern. You may have irregular or no bleeding, or bleeding on and off throughout the time when you're taking contraception.

Interaction of hormonal contraception with other medicines

Talk to your GP or pharmacist before you take any other medicines or herbal remedies at the same time as hormonal contraceptives.

Combined and progestogen-only oral contraceptives can become less effective if you're taking certain other medicines. These include medicines used to treat epilepsy, such as carbamazepine and phenytoin, and some medicines used to treat bacterial infections, particularly rifabutin and rifampicin.

St John's wort can also cause combined oral contraceptives to become less effective.

Some antibiotics, such as ampicillin and doxycycline, may reduce the effectiveness of combined oral contraceptives. You should use other forms of contraception, for example a condom, while you're taking a course of antibiotics and for seven days after stopping.

Names of common hormonal contraception

Examples of the main types of hormonal contraception are shown in the table.

You may have noticed that your medicine has two or more names. All medicines have a generic name, which is its official medical name. Many medicines also have at least one brand name, which is the trade name. Generic names are written in lower case and brand names start with a capital letter.

For answers to frequently asked questions on this topic, see Common questions .

For sources and links to further information, see Resources .