Combined OC (Levonorgestrel / Ethinyl Estradiol)

Hormonal Contraceptiveprescriptionoral · inferred

Combined oral contraceptive containing levonorgestrel (progestin, t1/2 ~24h) and ethinyl estradiol (estrogen, t1/2 ~12h). Brands: Alesse, Levlen, Seasonique. Steady state in ~7 days. Take at same time daily.

Projected serum levels — 1 pill (≈ 0.17 mg), once daily

Maintenance schedule: 1 pill (≈ 0.17 mg) once daily (oral).

Modeled steady state after ~1 days: peak ≈ 0.064 mg, trough ≈ 0.003 mg body load. Population-based estimate over 15 days for a reference dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category: Hormonal Contraceptive
Route modeled: Oral
Model confidence: inferred
Half-life: 4.9 h
Common dose: 1 pill (≈ 0.17 mg)
Suggested maximum: 1 pill/day
Reference dose range: 0.50–1 pill (single dose)
Suggested cadence: once daily

Documented interactions

danger
Carbamazepine (Tegretol) + Combined OC (Levonorgestrel / Ethinyl Estradiol) CYP induction
Carbamazepine (Tegretol) inducer of CYP3A4 predicted to change Combined OC (Levonorgestrel / Ethinyl Estradiol) AUC by ~0.31x
danger
Combined OC (Norgestimate / Ethinyl Estradiol) + Combined OC (Levonorgestrel / Ethinyl Estradiol) Stacked effects
Combined OC (Levonorgestrel / Ethinyl Estradiol) and Combined OC (Norgestimate / Ethinyl Estradiol) both push the androgen receptor, estrogen receptor alpha, and progesterone receptor in the same…
danger
Efavirenz (Sustiva) + Combined OC (Levonorgestrel / Ethinyl Estradiol) CYP induction
Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Combined OC (Levonorgestrel / Ethinyl Estradiol) AUC by ~0.21x
danger
Nicotine + Combined OC (Levonorgestrel / Ethinyl Estradiol) Contraindicated
Smoking while on combined OCs dramatically increases risk of blood clots, stroke, and heart attack. Risk increases with age (especially >35).
danger
Norgestimate + Combined OC (Levonorgestrel / Ethinyl Estradiol) Stacked effects
Combined OC (Levonorgestrel / Ethinyl Estradiol) and Norgestimate both push the androgen receptor, estrogen receptor alpha, and progesterone receptor in the same direction.
danger
NuvaRing (Etonogestrel / EE Vaginal Ring) + Combined OC (Levonorgestrel / Ethinyl Estradiol) Stacked effects
Combined OC (Levonorgestrel / Ethinyl Estradiol) and NuvaRing (Etonogestrel / EE Vaginal Ring) both push the androgen receptor, estrogen receptor alpha, and progesterone receptor in the same…

Serum checks 138 modeled interaction pairings for combined oc (levonorgestrel / ethinyl estradiol) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

Pharmacokinetics of Single and Multiple Doses of Ethinyl Estradiol and Levonorgestrel in Relation to Smoking Crawford FE et al. · Clinical Pharmacology & Therapeutics, 1988 DOI
Characterized EE and LNG pharmacokinetics showing smoking increases EE clearance by 50%, potentially reducing contraceptive efficacy in smokers.
Pharmacokinetics of Levonorgestrel and Ethinylestradiol in 9 Women Who Received a Low-Dose Oral Contraceptive Kuhnz W et al. · Contraception, 1992 DOI
Three-month PK study showing levonorgestrel accumulates at steady state with elimination half-life increasing from 20h to 24-26h with chronic dosing.
New Low-Dose Extended-Cycle Pills with Levonorgestrel and Ethinyl Estradiol: An Evolutionary Step in Birth Control Nelson AL · International Journal of Women's Health, 2010 DOI
Review of extended-cycle OC formulations pharmacology including continuous hormone exposure benefits and reduced hormone-free interval bleeding.

3 published studies referenced in the app, each with a plain-language summary.