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Birth control pills

The combined pill. Find out all you need to know about this common method of contraception.

What are birth control pills?

Birth control pills (oral contraceptives) are pills that you take to prevent pregnancy. These pills contain small amounts of synthetic hormones.

What are the different types of contraceptive pills?

There are two main types of contraceptive pill. The ‘combined’ pill is the most commonly used (‘the pill’). These pills (there are lots of different brands) contain manmade forms of two hormones naturally produced by a woman’s ovaries: oestrogen and progesterone. The other type of pill is called the progesterone-only pill, or ‘mini-pill’, and only contains progesterone.

How does the combined pill work?

The hormones in the combined pill:
  • Stop the ovaries from releasing an egg each month (ovulation). If there is no egg, then there is nothing for the sperm to fertilise, so pregnancy cannot take place
  • Cause the cervix to produce thicker and scantier mucus so that sperm cannot easily swim through it and reach the egg
  • Cause the lining of the uterus to become thinner, making it more difficult for a fertilised egg to implant there.

How do I take the pill?

Combined pills usually come in packs of 21 or 28. If you are using a 21-pill pack, take one pill at the same time every day for three weeks. Stop taking the pills for seven days and then start a new pack. You are immediately protected against pregnancy if you start taking the pills on the first day of your next period. If started on any other day, an extra method of contraception must be used for seven days.

If you are using the 28-day pack, take one pill every day for four weeks and then start a new pack the next day. The last seven pills contain no medication for birth control; they just keep you in the habit of taking a pill every day.

It is important to try to take the pills at approximately the same time every day.

Your period will usually come within a day or two of taking the last hormone-containing pill. You will have your period either during the seven days you are taking the inactive pills (28-day packet) or during your seven pill-free days (21-day packet).

Advantages

What are the advantages of this method of contraception?
  • The pill is highly effective and reliable (over 99% effective if taken according to instructions). If you follow the instructions for taking the pill exactly, you have about a 1 in 500 chance of becoming pregnant.
  • Oral contraceptive pills are easy to take
  • The pill does not interfere with sex
  • The pill protects against cancer of the womb (uterus) and cancer of the ovary
  • There is a reduction in the risk of ovarian cysts and ectopic (tubal) pregnancy
  • Periods are usually shorter, lighter and less painful
  • Risk of fibroids (non-cancerous tumours in the womb) is reduced
  • Premenstrual tension is reduced
  • There is a lower incidence of pelvic inflammatory disease (PID)
  • Certain pill preparations may improve acne
  • There is less incidence of fibrocystic disease and fibro-adenoma (benign tumours) of the breast.

Disadvantages

What are the disadvantages of this method of contraception?
  • You have to remember to take the pill every day
  • Certain side effects may be troublesome
  • The pill is available on prescription only
  • Certain medications may interfere with its efficacy
  • The pill is not suitable for everyone
  • It may not be effective if you have nausea and vomiting
  • Some research links the pill with breast cancer and cervical cancer
Frequently asked questions

What if I forget to take a pill?
If you forget to take a pill, you will not have the same level of protection and you are at risk of becoming pregnant. Read the instructions on your pack carefully or phone your GP.

  • If you are less than 12 hours late:
Take the last pill you missed and then take the next pill at the usual time. Continue on with the rest of the pack as usual. You do not have to take any extra contraceptive precautions and are still protected against pregnancy.

  • If you are more than 12 hours late:
Take the last pill you missed and then take the next one at the usual time. However, there is a risk of pregnancy so you need to use an extra method of contraception (e.g. condoms) for seven days.

  • If there are seven or more pills left in the pack after the missed pill:
When you finish the pack, take the usual seven-day break before you begin the next pack.

  • If there are less than seven pills left in the pack:
Finish the pack and begin the next pack immediately without taking any break.

  • If you miss three or more pills:
Stop taking the pills and use a different birth control method until your next period starts. If your period doesn’t come, visit your doctor for a pregnancy test.

  • If you have vomiting or diarrhoea, you may not have absorbed the pill:
Contact your doctor and use extra contraceptive precautions. You may get some menstrual bleeding or spotting if you miss taking your pills.

What if I want to get pregnant?
When you want to get pregnant, it is recommended that you wait until you have had at least two normal menstrual periods after stopping the pill. You should not have any problem becoming pregnant just because you have been on the pill.

Should I take a few months break now and again while I am taking the pill?
There are no known benefits to your health or fertility from ‘taking a break’ from the pill and it is not recommended.

What are the possible side effects of the pill?
  • Irregular bleeding or spotting between periods for the first few months
  • Nausea and vomiting
  • Weight gain
  • Breast swelling and tenderness
  • Increased appetite
  • Mood changes/depression
  • Headaches
  • Fluid retention
  • Very light or missed periods
  • Increased blood pressure
  • Dizziness.
Many of these side effects will settle down after a short while. However, you should call your doctor if you have:

  • Leg pain or swelling
  • Loss of vision or double vision
  • Problems with your menstrual periods, such as bleeding between periods, prolonged periods or missed periods
  • More headaches than usual
  • Numbness of the arms, legs, or any other part of your body
  • Queries about missed pills or other side effects.
What about blood clots?
Taking the pill can increase the risk of blood clots in the legs or lungs. Therefore, women with any history of blood clots or any risk factors for blood clots cannot take the pill. Smoking increases the risk of blood clots. Contact your doctor immediately if you have any pain or swelling in your legs, or any chest pains/shortness of breath.

Remember:
  • The pill may not suit everyone. Sometimes your doctor needs to try different preparations to find one to suit you
  • Have your blood pressure checked regularly while you are taking the pill
  • Birth control pills do not protect you from sexually transmitted diseases or AIDS
  • Some medicines can interfere with the pill and reduce its effectiveness. These medicines include some antibiotics, anticonvulsants and anti-fungal treatments. Always tell your doctor about any other medicines (including alternative medicines) that you are taking.
Who should not take the combined pill?
  • The combined pill is not advisable for smokers over the age of 35
  • You should not take the combined pill if you have:
  • A history of blood clots, heart attack, or stroke
  • Valvular heart disease
  • High blood pressure
  • Diabetes
  • Severe headaches/migraine
  • Cancer of the breast or uterus
  • Abnormal vaginal bleeding
  • Jaundice (yellowing of your skin) when you were pregnant or used hormones for birth control
  • Active liver or gallbladder disease
  • Allergy to the hormones in birth control pills
  • Recent long period of bed rest after major surgery, or a broken bone in plaster
  • Suspected pregnancy
  • Breastfeeding

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