Information on Combined Oral Contraceptive Pills

1. Background Information

  • Combined oral contraceptive (COC) pills contain two synthetic hormones—oestrogen and progestogen. It acts by suppressing ovulation.
  • It is highly effective and the failure rate is less than 1% if taken properly.
  • It can be a 21-day regimen in which all pills contain hormones and users have to stop for 7 days on finishing each pack, or a 28-day regimen which includes 21 hormone containing active pills followed by 7 inactive placebo pills and users can start a new pack immediately after finishing one. Menses usually occurs during the 7 days of pill free interval or when you are taking the placebo tablets.
  • Clients should consult a doctor before commencing the pills.

2. Method of Administration

  • Women should commence the pills within the first 5 days of menses and condoms are required for extra protection for 7 days.
  • Pills should be taken at the same time every day.

3. Side Effects

  • Some women may have nausea, vomiting, dizziness, headache, breast engorgement or weight gain, etc. shortly after starting COC pills. Most of these symptoms will subside after few weeks.

4. Please seek medical assessment as soon as possible and tell your doctor you are using combined oral contraceptive pills, if you have the following symptoms:

  • Bad fainting attack or collapse, severe headache, marked asymmetrical disturbance of vision (especially loss of visual field or blurring of vision), slurring of speech, weakness or paraesthesia affecting one side or one part of the body, unexplained breathlessness with or without coughing blood, severe central chest pain or sharp pains in either side of chest aggravated by respiration, severe abdominal pain or severev calf pain (not related to trauma nor after exercise), high blood pressure or jaundice.

5. Please return to Maternal and Child Health Centre (MCHC) for assessment for suitability to continue your contraceptive pill, if you have the following conditions:

  • Have any signs and symptoms of pregnancy
  • Newly diagnosed diseases, e.g. heart disease, stroke, diabetes mellitus, hypercholesterolemia (increase in lipid level), thromboembolic disease, cancer or other newly diagnosed medical and surgical diseases
  • Having chronic illness (e.g. diabetes mellitus, hypertension) or taking long term medication (e.g. anti-epileptics, antidepressants)
  • Plan for an operation
  • Family history of heart disease, stroke, thromboembolic disease or other illness

6. The Pill and Thrombosis

  • There is a risk of thromboembolic disease whether you are taking the pill or not. Women who take oral contraceptive pills will have higher risk of developing a blood clot in a vein when compared with normal women, but lower than pregnant women.
  • Studies showed that women who take the pill have an increased risk of developing blood clots which can block a vein or an artery. In serious case, it can cause deep vein thrombosis, pulmonary embolism, stroke and heart attack.
  • Women with higher risk in developing a blood clot in a vein or in an artery, may not be a suitable person to use the pill:
    • The following women have higher risk in developing a blood clot in a vein: e.g. overweight, older, immobile, pregnant, or family history of a blood clot in a vein.
    • The following women have higher risk in developing a blood clot in an artery: e.g. heart disease, high blood pressure, hypercholesterolemia (increase in lipid level), diabetes mellitus, smoker, overweight, older, or family history of blood clots in an artery.

7. The Pill and Cancers

  • Cancers can develop whether or not you are taking the oral contraceptive pills.
  • Ovarian and endometrial cancer: Studies suggested that women who take the pill have a 40% to 50% decreased in risk of developing ovarian cancer and endometrial cancer.
  • Breast cancer: Studies showed that for women at the same age, pill taker has slightly higher to similar rate of breast cancer than non-pill taker. After stop taking pills, the risk will be dropped gradually and the risk of breast cancer is the same as those who have not taking pills after stopped the pills for 10 years.
  • Cervical cancer: There is an increased in risk of cervical cancer in pill taking women. However, there is still inconclusive conclusion on whether the increase in risk of cervical cancer was directly related to the pill; or sexual active at younger age, or previous history of sexual transmitted disease, or have multiple sexual partners.

8. Note for missing pills

  • Missing 1 hormonal pill
    • Please take yesterday's missed pill immediately
    • Take the remaining pills as your usual schedule
  • Missing 2 or more hormonal pills
    • Please take yesterday's missed pill immediately (Throw away the other missed pills)
    • Take the remaining pills as your usual schedule
    • Use condoms as backup contraception in the coming 7 days for protection against pregnancy
    • Please return to MCHC as soon as possible for counselling and assessing the need for emergency contraception
  • Missing any of the inactive pills
    • Discard the missed inactive pills and continue pill taking

Before you seek medical advice, please clearly record:

  1. Accurate date(s) of missing pill(s)
  2. Date(s) with sexual activity during the missing pill period and 2 weeks prior to facilitate further management

9. Taking other medication

  • Please inform your doctor you are taking oral contraceptive pills before taking other medication, as some medications may affect the contraceptive effect of contraceptive pills.

If you have any queries, please seek advice from your family doctor or return to your MCHC for advice.

(Content revised 06/2013)