Noriday (Norethisterone)

Norethisterone acts on the hormonal pathways that regulate the menstrual cycle and ovulation. It is employed for several recognised clinical purposes:

• Contraception: Provides reliable hormonal birth control for women of child‑bearing age.
• Endometriosis: Reduces pain and lesion growth by suppressing menstrual bleeding.
• Menstrual disorders: Treats irregular cycles, heavy bleeding, or amenorrhoea by stabilising the endometrium.
• Hormone replacement therapy: Used as part of combined regimens to alleviate menopausal symptoms.

• Norethisterone is a synthetic progestogen that binds to progesterone receptors in the hypothalamic‑pituitary‑ovarian axis, inhibiting the luteinising hormone surge and thereby suppressing ovulation. It also induces endometrial transformation that renders the uterine lining unsuitable for implantation, contributing to its contraceptive effect.

Norethisterone may cause a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Breast tenderness: discomfort or swelling of the breasts.
• Headache: occasional tension‑type headaches.
• Weight gain: modest increase in body weight.
• Mood changes: irritability or emotional fluctuations.
• Menstrual irregularities: spotting or breakthrough bleeding.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Severe allergic reaction: rash, swelling, or anaphylaxis.
• Liver dysfunction: jaundice or abnormal liver enzymes.
• Depression: new or worsening depressive symptoms.
• Visual disturbances: blurred vision or eye pain.
• Unexplained vaginal bleeding: may indicate underlying pathology.

Before prescribing Norethisterone, clinicians should consider several safety aspects.

• Assess medical history: screen for thromboembolic risk, liver disease, or hormone‑sensitive cancers.
• Contraindication in pregnancy: avoid use in known or suspected pregnancy.
• Monitor liver function: consider baseline and periodic liver enzyme tests.
• Caution with smoking: advise women over 35 who smoke to discontinue use.
• Review concomitant medications: evaluate potential drug interactions.
• Store at ambient temperature: keep in the original packaging, protect from moisture and direct sunlight.

Norethisterone can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Combined hormonal contraceptives: concurrent use may increase progestogenic load.
• Antifungal azoles (e.g., ketoconazole): may raise plasma concentrations of norethisterone.
• Enzyme‑inducing antiepileptics (e.g., carbamazepine): can markedly reduce contraceptive effectiveness.

Moderate Interactions (Monitor Closely)

• Rifampicin and other strong antibiotics: may lower drug levels, requiring alternative contraception.
• St. John’s wort: may decrease efficacy through enzyme induction.
• Selective serotonin reuptake inhibitors: may increase risk of mood changes or bleeding.