ModerateAntiepileptics. Carboxamide derivatives×Estrogens — natural and semisynthetic
Updated · Methodology
Mechanism
Carbamazepine is a strong CYP3A4 inducer. Plasma oestradiol falls by 40–60%. On menopausal hormone therapy, menopausal symptoms may return; on combined oral contraceptives, unplanned pregnancy risk arises.
Symptoms
Return of vasomotor symptoms: hot flushes, night sweats, sleep disturbance. On oral contraceptives: breakthrough bleeding, conception risk.
Management
On menopausal hormone therapy, double the oestradiol dose or switch to transdermal forms (patch, gel — minimal hepatic metabolism). For contraception on carbamazepine, combined oral contraceptives are unsuitable — choose a levonorgestrel IUS, copper IUD, or depot medroxyprogesterone acetate.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Tegretol (carbamazepine) prescribing information (2009)– ; DailyMed setid 8d409411-aa9f-4f3a-a52c-fbcb0c3ec053
- AEMPS: Ficha técnica: Estradiol (nº registro 47814), sección 4.5 (2026)– AEMPS, CIMA, nº registro 47814, revisión 02/2026, sección 4.5