Combined pill (oestrogen / progestogen)
- Ethinylestradiol / levonorgesterol (standard dose)
- Ethinylestradiol / norethisterone
Progestogen only pill
- Levonorgesterol
- Noresthiserone
Contraindications
- History of venous or arterial thrombosis
- Personal risk factors for arterial disease and thromboembolism
- Migraine with aura
- Transient ischaemic attacks
- SLE
- Undiagnosed vaginal bleeding
- Acute porphyria
- History of breast cancer
- Liver disease
Cautions
- Strong family history of arterial disease
- Diabetes mellitus
- Hypertension
- Smoking
- Age (>35)
- Obesity
- Migraine without aura
The progesterone only pill may be more suitable for patients with these conditions.
Oestrogen inhibits follicle-stimulating hormone (FSH) release and therefore follicle development. Progestogen inhibits luteinizing hormone (LH) release and therefore ovulation, and makes cervical mucus inhospitable for sperm; the combined effect is to make the endometrium unsuitable for implantation. Progestogen only pills do not have any effect on FSH and act only on LH and ovulation; they are less reliable than the combined pill.
Both combined oral contraceptive pill and progesterone only contraceptive pill are taken orally.
(Other methods of hormone-based contraception are available including combined hormonal vaginal ring and progestogen only parenteral contraceptives.)
Combined OCP
- Headache
- Depression
- Hypertension
- Thromboembolism
- Liver disease and gallstones
Progestogen-only OCP
- Fluid retention, abdominal and lower back pain
Long term use of oral contraceptives can cause amenorrhoea.
Oral contraceptives increase the risk of breast cancer, and the combined pill is also associated with an increase in cervical cancer.
Patients should be told that any diarrhoeal illness may affect the efficacy and they should take additional precautions. Instructions for what to do if a pill is missed should also be given.
Metabolism is by the hepatic cytochrome P450 enzyme pathway. The minimum dose possible is given to minimise side effects, therefore any enzyme potentiating drugs increase the possibility the OCP will be ineffective. Recent guidance suggests that this is only important with rifampicin and other antibiotics should not be problematic.
