Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CRYSELLE vs ALYACEN 1/35
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Cryselle is a combination oral contraceptive containing ethinyl estradiol and norgestrel. It inhibits ovulation by suppressing gonadotropin release, primarily through estrogenic and progestogenic effects on the hypothalamic-pituitary axis. It also increases cervical mucus viscosity and alters endometrial structure, impeding sperm penetration and implantation.
Combination hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.
Prevention of pregnancy,Off-label: Acne vulgaris, dysmenorrhea, menorrhagia, endometriosis-associated pain, menstrual cycle regulation, emergency contraception (sometimes off-label)
Prevention of pregnancy
One tablet (0.3 mg norgestrel/0.03 mg ethinyl estradiol) orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo.
One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.
Terminal elimination half-life approximately 24 hours (range 16-36 h), with clinical significance for once-daily dosing.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Ethinyl estradiol undergoes first-pass metabolism in the gut wall and liver, primarily via CYP3A4, and is also involved in conjugation (glucuronidation and sulfation). Norgestrel is metabolized in the liver via reduction and conjugation, with the active isomer levonorgestrel undergoing hydroxylation by CYP3A4.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal (50% as metabolites, 20% unchanged), fecal (30%), with enterohepatic recirculation.
Renal excretion of metabolites (primarily ethinyl estradiol and norethindrone conjugates) accounts for approximately 50-60% of elimination; fecal excretion accounts for 30-40%. Unchanged drug excretion is minimal (<5%).
95-98% bound to serum albumin and sex hormone-binding globulin.
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Approximately 2 L/kg (40-60 L total), indicating extensive tissue distribution.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: 85-90% due to first-pass metabolism; otherwise 100% for IV.
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. Contraindicated in patients with acute or chronic renal failure due to potential for fluid retention and electrolyte disturbances.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment or acute renal failure due to potential fluid retention and electrolyte disturbances.
Contraindicated in patients with Child-Pugh Class B or C cirrhosis or active liver disease. Use with caution in Child-Pugh Class A; consider alternative therapy if hepatotoxicity risk outweighs benefits.
Contraindicated in patients with hepatic impairment, including Child-Pugh class B or C, due to impaired metabolism of estrogen and progestin. Not recommended in patients with active liver disease or history of liver tumors.
Not indicated for premenarchal girls. Postmenarchal adolescents: same dosing as adults (0.3 mg norgestrel/0.03 mg ethinyl estradiol once daily for 21 days, then 7 days placebo).
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults. Safety and efficacy established for contraception; weight-based dosing not applicable.
Not indicated for use in postmenopausal women. No specific dosing adjustments recommended for elderly patients, but use with caution due to increased risk of thromboembolic events and cardiovascular disease.
Not indicated for use after menopause due to lack of benefit and increased risks (e.g., cardiovascular, thromboembolic events). If used, monitor for fluid retention, hypertension, and glucose intolerance.
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive use. This risk increases with age and with heavy smoking (≥15 cigarettes per day) and is marked in women over 35 years of age. Women who use combination oral contraceptives should be strongly advised not to smoke.
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
Cardiovascular events (thrombophlebitis, venous thrombosis, arterial thromboembolism, myocardial infarction, stroke, pulmonary embolism),Hepatic neoplasia (benign and malignant),Gallbladder disease,Carbohydrate and lipid metabolism effects,Elevated blood pressure,Ocular lesions (retinal thrombosis),Headache (including migraine with focal symptoms),Irregular bleeding,Depression,Lactation (may decrease milk production),Hereditary angioedema exacerbation,Chloasma
Thrombotic disorders (e.g., DVT, PE, stroke, MI),Cerebrovascular disease,Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate and lipid effects,Ocular lesions,Hereditary angioedema,Chloasma,Menstrual irregularities,Pregnancy exclusion prior to initiation
Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease (current or history),Known or suspected breast carcinoma,Endometrial carcinoma or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma (current or history),Known or suspected pregnancy,Hypersensitivity to any component,Heavy smoking (≥15 cigarettes/day) and age >35 years
Venous or arterial thrombotic/thromboembolic disease (current or history),Cerebrovascular disease,Coronary artery disease,Known or suspected breast cancer,Endometrial or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma,Known or suspected pregnancy,Hypersensitivity to any component,Smoking in women over 35
No specific food interactions; however, grapefruit juice may increase estrogen levels slightly but clinical significance is minimal. St. John's Wort reduces contraceptive efficacy. High-fat meals can increase absorption of estrogen.
No significant food interactions. Grapefruit juice may increase estrogen levels, but clinically not a concern. Avoid excessive alcohol, which may impair liver function and increase estrogen exposure. Maintain a healthy diet, as weight gain is possible.
CRYSELLE (levonorgestrel/ethinyl estradiol) is contraindicated in pregnancy. First trimester: no increased risk of major birth defects from inadvertent use, but postmarketing data limited. Second and third trimesters: associated with increased risk of fetal harm including cardiovascular and genital anomalies, and potential feminization of male fetuses due to progestin exposure.
Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including cardiovascular defects and limb reduction defects. Second/third trimesters: Potential for urogenital abnormalities and feminization of male fetus. Exposure is associated with subsequent development of clear cell adenocarcinoma of vagina/cervix in female offspring (DES-related).
Excreted in breast milk; M/P ratio approximately 0.1-0.5 for levonorgestrel and 0.02-0.1 for ethinyl estradiol. Combined hormonal contraceptives may reduce milk production and quality; use alternative contraception during breastfeeding. Not recommended while nursing.
Small amounts of contraceptive steroids and/or metabolites have been identified in breast milk. M/P ratio: Not specifically determined for this combination; ethinyl estradiol M/P ratio ~0.02-0.04. Use may reduce milk production and quality. Breastfeeding not recommended during use. Alternative contraception advised.
No dosing adjustments applicable as use is contraindicated during pregnancy. Pharmacokinetic changes of pregnancy (increased volume of distribution, altered metabolism) would require dose increase if used, but due to fetal risk, do not administer.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
Crysell is a combination oral contraceptive containing ethinyl estradiol and norgestrel. It is also used off-label for dysmenorrhea and endometriosis-associated pain. Monitor for hypertension, thromboembolic events, and hepatic adenoma. Smoking increases thromboembolism risk, especially in women over 35. Breakthrough bleeding common in first 3 cycles; if persistent, rule out pregnancy or missed pills. Altered efficacy with hepatic enzyme inducers (e.g., rifampin, carbamazepine).
ALYACEN 1/35 is a combination oral contraceptive containing ethinyl estradiol 35 mcg and norgestimate 1 mg. It is indicated for the prevention of pregnancy and for the treatment of moderate acne vulgaris in females ≥15 years of age who desire an oral contraceptive. Monitor for thromboembolic events, especially in smokers over 35 or those with migraine with aura. Use with caution in patients with liver impairment or history of cholestatic jaundice. The pill-free interval should not exceed 7 days; missed pills increase ovulation risk. Consider non-hormonal backup if vomiting or diarrhea occurs within 4 hours of dosing.
Take one tablet daily at the same time; do not skip doses.,Missed pills increase pregnancy risk; follow instructions in package insert.,Antibiotics (except rifampin) do not decrease effectiveness, but rifampin requires backup contraception.,Smoking while on this pill increases risk of blood clots, especially if over 35.,Report severe headaches, vision changes, chest pain, leg swelling or pain, or shortness of breath.,This does not protect against HIV or other STIs.,Breakthrough bleeding is common in first few months; contact provider if heavy or persistent.,If vomiting or diarrhea within 4 hours of a pill, take another pill and use backup contraception.
Take one tablet daily at the same time each day; do not skip doses.,Use an additional non-hormonal contraceptive (e.g., condoms) if you miss a pill, have vomiting, or diarrhea.,Smoking while on this pill increases the risk of blood clots and stroke, especially if you are over 35.,Contact your healthcare provider immediately if you have chest pain, leg pain/swelling, sudden vision changes, or severe headache.,This medication does not protect against HIV or other sexually transmitted infections.,Store at room temperature, away from moisture and heat.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CRYSELLE vs ALYACEN 1/35, answered by our medical review team.
CRYSELLE is a Oral Contraceptive that works by Cryselle is a combination oral contraceptive containing ethinyl estradiol and norgestrel. It inhibits ovulation by suppressing gonadotropin release, primarily through estrogenic and progestogenic effects on the hypothalamic-pituitary axis. It also increases cervical mucus viscosity and alters endometrial structure, impeding sperm penetration and implantation.. ALYACEN 1/35 is a Oral Contraceptive that works by Combination hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CRYSELLE and ALYACEN 1/35 depend on the specific clinical indication. These are both Oral Contraceptive agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CRYSELLE is: One tablet (0.3 mg norgestrel/0.03 mg ethinyl estradiol) orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo.. The standard adult dose of ALYACEN 1/35 is: One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between CRYSELLE and ALYACEN 1/35 in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. CRYSELLE is classified as Category C. CRYSELLE (levonorgestrel/ethinyl estradiol) is contraindicated in pregnancy. First trimester: no increased risk of major birth defects from inadvertent use, but postmarketing data . ALYACEN 1/35 is classified as Category C. Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.