Combined Oral Contraceptive Pill - How to take the 21 day pill

If you follow these instructions, the failure rate of this method of contraception is very low indeed, in the order of 1 in 400.

The First Packet
Start it on the first day of your next period. You are then protected immediately. Some brands of pill contain the same dose of hormone in each pill. Other brands have phased doses throughout the packet. Whatever type you have, get into the habit of taking it in the correct order. Continue the packet by taking one pill at roughly the same time each day. When this packet is finished, go 7 days without taking a tablet. You will usually get some bleeding during this pill free week.

Following Packets
Start the next packet after the 7 pill free days. This will always be on the same day of the week as you started the first packet. Your routine is then as follows: 21 days - one pill each day; 7 days - no pills. You are protected for all 28 days.

These are usually lighter when you are on the pill (but not always). During the early months on the pill some unexpected bleeding may occur during the packet. If this does occur, don't stop taking the pill. If it persists, tell the nurse. You may also miss a period. If you have taken the pill regularly, it is most unlikely that you are pregnant. But, if you suspect that you are pregnant, or if you miss a second period, do a pregnancy test. However, keep taking your pills as usual until you see the nurse.

Side effects
Other common side effects which can persist for the first 2-3 packs are breast tenderness and nausea. It is worth persisting with the pill despite early side effects as they will usually settle.

If you forget a pill
Take it as soon as you remember, and the next one at your normal time. If you are more than 12 hours late then please follow these instructions: (1) If it is in the first or second week of pills, use extra precautions for the next seven days. (2) If it is the last week of pills, take the next packet straightaway and do not have a pill-free week. Extra precautions are not necessary. At the end of the second packet stop and have a break as normal.

Remember: You must not lengthen the 7 day break in between packets. The most dangerous pills to forget are those at the end of the pack and in particular, those at the beginning of the pack. If you do forget pills and think you could be at risk of pregnancy, you can take the emergency pill.

Gastrointestinal upsets
Vomiting within two hours of taking the pill, any repeated vomiting, or severe diarrhoea may well prevent the pill from working. A single vomit more than two hours after taking the pill should not affect it. Follow the rules for forgetting a pill, both during the tummy upset and for seven days afterwards. Then continue to take it normally.

Some antibiotics stop the pill working. The safe thing is to follow the rules for forgetting the pill, both during the course and for seven days after.

Other medicines
Make sure that your doctor knows about any other medication that you are on when you start the pill. None of the medicines or tablets that you buy from the chemist should interfere with the pill, but beware of St Johns Wort; recent evidence has demonstrated that it interacts with the pill, making it less effective.

The Risks
You should be aware that the pill has some possible risks and side effects, although very few women have serious problems. For most women the benefits of the pill are more than the disadvantages. Make sure that the nurse knows if you have a personal or family history of heart disease, stroke, thrombosis or migraine. If you have any unusual symptoms, consult your doctor immediately. It is usually better to stop the pill four weeks before a planned operation. Discuss this with the doctor or nurse. You should try not to smoke if you are going to take the Pill.

See the doctor at once if you have any of these

  • Painful swelling in the leg
  • Severe pain in the chest or stomach
  • Breathlessness or coughing with blood
  • A bad fainting attack or collapse
  • Unusual headaches. Difficulty with speech/sight
  • Numbness or weakness of a limb.

      The risk of a thrombosis is very small but these are the current figures
      Background risk 5 per 100,000
      Risk in pregnancy 60 per 100,000
      Second generation pill (microgynon, ovranette, loestrin, triphasic pills) 15 per 100,000 Third generation pills (femodene, minulet, marvelon, mercilon) 25 per 100,000.>

      Dianette, which is a combination of oestrogen and a hormone called cyproteone acetate is used as a treatment for acne and excess body hair. It is also a contraceptive. Evidence has shown that it has a slightly higher risk of thrombosis than other contraceptive pills and so it should only be taken until the acne or hirsutism has resolved. If you wish to continue with a hormonal method of contraception, the advice is that you should switch to a preparation which carries a lower risk. Discuss with your medical advisor.

      If you have any concerns re the risk, please discuss with the nurse. Advice from the Chief Medical Officer states that the third generation pills can be prescribed first line provided that women are informed of the risk.

      The risk of suffering a deep vein thrombosis is increased during flights, particularly long haul flights. You can minimise the risk by moving your legs regularly, avoid alcohol, and drinking plenty of water. Some experts are recommending low dose aspirin and the wearing of special support socks, if you are at high risk.

      Sexually Transmitted Disease
      The Pill does not protect against sexually transmitted infections. Please ensure that your partner uses a condom even if you are taking the Pill.
      The pill that you are taking is a very effective contraceptive. However, sexually transmitted infections are increasingly common and can be dangerous. HIV can be transmitted by heterosexual intercourse; genital warts also are very infectious and may lead to cervical cancer. Chlamydia can cause pelvic inflammatory disease, leading to subfertility. Using a condom will provide the best protection against these and other infections.

      Cervical Smears
      Once a woman is sexually active she should have regular cervical smears, starting 6-12 months after first intercourse from the age of 25. The procedure is quick and simple. Regular smears help to reduce the risk of cervical cancer.

      Repeat Prescriptions
      These can usually be obtained from your practice nurse. Check arrangements for repeats with your own health centre.

      Further information

This article published on
25 November 2005

Next review date 11/1/2013


Contraception and pregnancy

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Reproductive system

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