Desogestrel: Drug Interactions

Major Interactions — Avoid or Monitor Closely

• ⚠Rifampicin — potent CYP3A4 inducer; reduces ethinylestradiol and progestin levels >50%; use additional contraception during and for 4 weeks after stopping rifampicin
• ⚠Anti-epileptics (carbamazepine, phenytoin, phenobarbital, topiramate ≥200mg) — CYP3A4 inducers reduce contraceptive efficacy; use additional barrier method or switch method
• ⚠HIV antiretrovirals (ritonavir-boosted regimens, efavirenz, nevirapine) — enzyme inducers; use barrier method
• ⚠St. John's Wort — CYP3A4 induction; reduces contraceptive efficacy; avoid concurrent use

Moderate Interactions — Use With Caution

• •Broad-spectrum antibiotics — current evidence does not support routine additional precautions except during vomiting/diarrhoea
• •Griseofulvin — hepatic enzyme induction; additional contraception recommended
• •ACE inhibitors / ARBs — drospirenone-containing OCP has anti-mineralocorticoid effect; hyperkalemia risk; monitor potassium
• •Warfarin — COC may increase or decrease anticoagulant effect; INR monitoring required
• •Lamotrigine — combined OCP significantly reduces lamotrigine levels (~50%); seizure risk; lamotrigine dose increase required

Food & Drink Interactions

• •Grapefruit juice — modest CYP3A4 inhibition; clinically minor effect on most hormonal contraceptives
• •High-fat meal — may slightly improve absorption of some formulations

Monitoring Requirements

Blood pressure (OCP contraindicated if BP >160/100); migraine history (COC contraindicated with migraine with aura due to stroke risk); VTE risk assessment; annual BP and weight check