Combined Oral Contraceptive Pill (COC)

COC need to be taken every day, usually for 21 days followed by a seven day break

Each packet of pills starts on the same day of the week (e.g. if you start your first packet on a Wednesday, every packet starts on a Wednesday)

Always start your next packet of pills, even if you are still bleeding or if you miss a bleed. The worst pills to miss are at the beginning of the packet

COC need to be taken at a regular time of day within a 24 hour time frame (window period) e.g. if you take your COC at 8am every day, you would need to take it no later than 8am the following day).

If 100 sexually active women don’t use any contraception, 80 to 90 will become pregnant in a year. If the pill is taken according to instructions it is over 99 per cent effective. This means that less than one woman in 100 will get pregnant in a year.

If the pill is not taken according to instructions, more women will become pregnant.

The main way the pill works is to stop the ovaries from releasing an egg each month (ovulation) and it also thickens the mucus from the cervix (making it difficult for sperm to move reach an egg) and it makes the lining of your uterus (womb) thinner so it is less likely to accept a fertilised egg.

There are lots of advantages of taking the COC, such as;

• Menstrual bleeds become regular, lighter and less painful

• May alleviate premenstrual symptoms

• Reduces the risk of some cancers such as ovarian, uterine and colon

• May reduce the risk of fibroids, ovarian cysts and non-cancerous breast disease

• May improve acne

• Normal fertility returns immediately after stopping the COC. 

• Temporary side-effects may last a few months and include headaches, nausea, breast tenderness and mood changes.

• Breakthrough bleeding (unexpected vaginal bleeding on pill taking days) is common when first starting the COC. It will improve, try and remember to take the pill at a set time of day. Missed a pill?

• The COC may increase your blood pressure

• The COC does not protect you against sexually transmitted infections, so you may need to use condoms

• The COC is not suitable for everyone so the doctor or nurse will ask about your own and your family’s medical history.

• The COC is not suitable for women who have had a thrombosis. The risk of venous thrombosis increases if you are overweight, a smoker, immobile for a long period of time or use a wheelchair, or a member of your immediate family had venous thrombosis before they were 45 years old.

• The risk of arterial thrombosis is increased if you smoke, are diabetic, have high blood pressure, are very overweight, have migraines with aura, or a member of your immediate family had a heart attack or stroke before they were 45 years old.

• Research suggests that users of the COC appear to have a very small increased risk of being diagnosed with breast cancer compared to non-users of hormonal contraception, but this reduces with time after stopping the COC.

• They are less effective than long-acting reversible methods of contraception 

Research has shown that the COC does not cause weight gain.

If you are healthy, don’t smoke and there are no medical reasons, the COC can be used until you are 50 years old. You may then need to change to another method of contraception.

The COC needs to be stopped if you experience:

• Pain in the chest, including any sharp pain which is worse when you breathe in

• Breathlessness

• You cough up blood

• Painful swelling in your leg(s)

• Weakness, numbness, or bad ‘pins and needles’ in an arm or leg

• Severe stomach pains

• A bad fainting attack or you collapse

• Unusual headaches or migraines that are worse than usual

• Sudden problems with your speech or eyesight

• Jaundice (yellowing skin or yellowing eyes).