Combined oral contraceptive (1st-generation progestogen) Pregnancy: Not indicated during pregnancy — if pregnancy occurs during medication, treatment should be withdrawn immediately (pregnancy is also listed as a contraindication). Like all norethisterone derivatives used for contraception, Brevinor has slight androgenic activity, and at doses higher than normally used in oral contraceptive and HRT formulations masculinisation of female foetuses has been observed. Most epidemiological studies of inadvertent foetal exposure to oestrogen/progestogen combinations indicate no teratogenic or foetotoxic effects. Breast-feeding: patients who are fully breast-feeding should not take Brevinor, since the oestrogen component may reduce the amount of milk produced and active ingredients or their metabolites have been detected in milk; the effect on breast-fed infants has not been determined.

Ethinylestradiol with norethisterone

Brand names: Ovysmen, Loestrin, Brevinor

A combined oral contraceptive of ethinylestradiol with norethisterone, a first-generation progestogen.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 tablet daily (Brevinor 0.5 mg/35 microgram tablets)

Route: Oral administration

Frequency: Initial cycle — 1 tablet taken at the same time each day from the first day of the menstrual cycle. Subsequent cycles — no tablets for 7 days, then a new course of 1 tablet daily for the next 21 days. This sequence of 21 days on treatment and 7 days off treatment is repeated for as long as contraception is required

STARTING — patients unable to start on the first day of the menstrual cycle may start on any day up to and including the 5th day of the menstrual cycle. Those starting on day 1 are protected at once; those delaying up to day 5 may not be protected immediately and another method of contraception should be used for the first 7 days of tablet-taking (suitable methods are condoms, caps plus spermicides and intra-uterine devices; the rhythm, temperature and cervical-mucus methods should not be relied upon). TABLET OMISSIONS — if a tablet is missed within 12 hours of the correct dosage time, take the missed tablet as soon as possible (even if this means taking 2 tablets on the same day) and contraceptive protection is maintained. If one or more tablets are missed for more than 12 hours from the correct dosage time, take the last missed tablet as soon as possible and continue the rest of the tablets in the normal manner, plus use extra contraceptive protection such as a condom for the next 7 days. Patients who have missed one or more of the last 7 tablets in a pack should start the next pack as soon as the present one has finished (i.e. without the normal seven-day gap). SWITCHING — from another oral contraceptive: take the first Brevinor dose on the day immediately after finishing the previous pack. AFTER CHILDBIRTH, MISCARRIAGE OR ABORTION — provided the patient is not breast-feeding, take the first dose on the 21st day after childbirth for immediate protection; if there is any delay, contraception may not be established until 7 days after the first tablet, so extra contraceptive methods are needed. After a miscarriage or abortion, the first dose may be taken on the next day, giving immediate protection. GASTRO-INTESTINAL UPSET — vomiting and diarrhoea may interfere with tablet absorption and reduce contraceptive efficacy; continue taking Brevinor but also use another contraceptive method during the upset and for the next 7 days (SPC §4.4). PAEDIATRIC — no paediatric posology is stated in this SPC section.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substances or to any of the excipients
History of confirmed venous thromboembolic disease (VTE), family history of idiopathic VTE, and other known risk factors of VTE
Thrombophlebitis, cerebrovascular disorders, coronary artery disease, myocardial infarction, angina, hyperlipidaemia, or a history of these conditions
Acute or severe chronic liver disease, including liver tumours, Dubin-Johnson or Rotor syndrome
History during pregnancy of idiopathic jaundice, severe pruritus or pemphigoid gestationis
Known or suspected breast or genital cancer
Known or suspected oestrogen-dependent neoplasia
Undiagnosed abnormal vaginal bleeding
A history of migraines classified as classical focal or crescendo
Pregnancy
Concomitant use with medicinal products containing ombitasvir/paritaprevir/ritonavir and dasabuvir, glecaprevir/pibrentasvir, or sofosbuvir/velpatasvir/voxilaprevir

Side effects

Slight nausea at first, weight gain or breast discomfort, which soon disappear
Gastro-intestinal symptoms; changes in libido and appetite
Headache; depression; exacerbation of existing uterine fibroid disease; changes in carbohydrate, lipid and vitamin metabolism
Spotting or bleeding during the first few cycles; menstrual bleeding usually becomes light and occasionally there may be no bleeding during the tablet-free days
Hypertension, usually reversible on discontinuing treatment, in a small percentage of women
Exacerbation of symptoms of hereditary and acquired angioedema (frequency not known)

Interactions

Medicinal products containing ombitasvir/paritaprevir/ritonavir and dasabuvir, glecaprevir/pibrentasvir, or sofosbuvir/velpatasvir/voxilaprevir — concomitant use is contraindicated (stated in SPC §4.3 cross-referring to §4.5; the full §4.5 interaction section was not captured in this bundle — clinician to review it)

Clinical monograph

How it works

Ovulation is inhibited through hypothalamic-pituitary suppression, with added contraceptive effect from cervical mucus thickening and an endometrium made unfavourable to implantation.

Prescribing in practice

All combined hormonal contraceptives carry VTE and arterial risk; norethisterone preparations are among the lower-risk options, but UKMEC contraindications must still be screened.
Assess for migraine with aura, cardiovascular risk factors and thrombosis history before prescribing.
Advise on missed-pill rules and reduced efficacy with enzyme inducers or significant gastrointestinal upset.

Monitoring

Check blood pressure and reassess cardiovascular and VTE risk at initiation and at periodic review.

Counselling the patient

Take at the same time each day and follow missed-pill advice.
The pill does not protect against sexually transmitted infections.
Seek urgent help for calf swelling, chest pain, breathlessness or sudden severe headache.

Evidence & guidelines

MHRA and UKMEC document the relative VTE risks of combined pills by progestogen type, with first-generation progestogens among the lower-risk group.

Reference: FSRH CHC guideline; UKMEC; MHRA Drug Safety Update; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways