Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACTAHIST vs ALESSE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.
Combination of ethinyl estradiol and levonorgestrel suppresses gonadotropin-releasing hormone (Gn RH) secretion from the hypothalamus, inhibiting pituitary release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), thereby preventing ovulation. Additionally, it thickens cervical mucus, impeding sperm penetration, and alters endometrial receptivity.
Symptomatic relief of allergic rhinitis,Urticaria,Off-label: motion sickness,Off-label: insomnia
Prevention of pregnancy,Treatment of moderate acne vulgaris (in women ≥15 years who have achieved menarche and desire contraception),Contraception in women with heavy menstrual bleeding (off-label)
1.34 mg (one capsule) orally twice daily.
One tablet (ethinyl estradiol 20 mcg, levonorgestrel 0.1 mg) orally once daily at the same time each day for 21 days, followed by 7 days of placebo. For initiation, start on the first day of menstrual period or first Sunday after onset of menses.
6.9 ± 1.7 hours in adults; prolonged to 12-18 hours in elderly or patients with hepatic impairment, requiring dosing interval adjustment.
Levonorgestrel: terminal half-life ~17-20 hours (range 11-25 hr). Ethinyl estradiol: biphasic; terminal half-life ~13-27 hours (mean ~17 hr). Clinical context: steady-state achieved within 5-7 days. The half-life supports once-daily dosing with at least 24-hour contraceptive coverage.
Hepatic metabolism via CYP450 enzymes (primarily CYP3A4 and CYP2D6); major metabolite is inactive.
Ethinyl estradiol is primarily metabolized by CYP3A4 and undergoes conjugation (glucuronidation and sulfation). Levonorgestrel is metabolized by CYP3A4 and reduction, with conjugation to glucuronide and sulfate conjugates.
Primarily renal (approximately 85% as unchanged drug and metabolites) and fecal (15%) via biliary elimination.
Renal: ethinyl estradiol (UE2) and levonorgestrel (LNG) metabolites primarily excreted in urine (UE2: ~40% as sulfate and glucuronide conjugates; LNG: ~25% as glucuronides). Fecal/biliary: ~40% (UE2) and ~45% (LNG) eliminated in feces via bile. Unchanged drug excretion is negligible.
92% bound to albumin.
Levonorgestrel: 97-99% bound to albumin and sex hormone-binding globulin (SHBG). Ethinyl estradiol: 98-99% bound, primarily to albumin (98.5%), with minor binding to SHBG. Free fractions: LNG ~1%, UE2 ~1.0-1.5%.
0.9 ± 0.3 L/kg, indicating extensive extravascular distribution.
Levonorgestrel: Vd ~1.8 L/kg (range 1.5-2.0 L/kg). Ethinyl estradiol: Vd ~2.5-3.5 L/kg (mean ~2.9 L/kg). Indicates extensive tissue distribution, including target organs (ovaries, endometrium, breast). Not clinically adjusted for obesity.
Oral: 68% ± 12% due to first-pass metabolism.
Oral: levonorgestrel ~95-100% (highly bioavailable). Ethinyl estradiol ~45-55% (first-pass metabolism reduces bioavailability; interindividual variability due to gut wall and hepatic conjugation). Both are prodrugs requiring hydrolysis for activity.
No dose adjustment required for mild to moderate renal impairment. Safety not established for severe impairment (GFR <30 m L/min).
No specific GFR-based dose adjustments are recommended; however, use with caution in patients with renal impairment due to potential fluid retention and hypertension.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not recommended for severe hepatic impairment (Child-Pugh C).
Contraindicated in patients with severe hepatic disease (Child-Pugh class C) or active liver disease. In mild to moderate impairment (Child-Pugh A or B), use only if benefits outweigh risks; no specific dose reduction guidelines are available.
Not indicated for pediatric patients under 12 years of age. Safety and efficacy not established.
Approved for postmenarchal adolescents; same dosing as adults: one tablet orally once daily for 21 days followed by 7 days of placebo. No weight-based adjustments are recommended.
No specific dose adjustment recommended; monitor for increased anticholinergic effects and cognitive impairment.
Not indicated for use in postmenopausal women; no specific geriatric dosing adjustments are necessary if used off-label, but consider increased risk of thrombotic events in older women.
None.
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive use. The risk increases with age, particularly in women over 35 years, and with heavy smoking (≥15 cigarettes per day). Women over 35 who smoke should not use this medication.
May cause drowsiness; caution when driving or operating machinery. Avoid alcohol. Use with caution in patients with narrow-angle glaucoma, prostatic hyperplasia, or urinary retention. Geriatric patients more sensitive to anticholinergic effects. Pediatric patients <6 years: not recommended.
Increased risk of thromboembolic disorders (venous and arterial),Cigarette smoking increases risk of cardiovascular events, especially in women over 35,Hepatic neoplasia (benign and malignant),Elevated blood pressure,Gallbladder disease,Carbohydrate and lipid metabolism effects,Headache/migraine,Depression,Uterine bleeding irregularities,Ocular lesions (e.g., retinal thrombosis),Carcinoma of the breast and reproductive organs (close monitoring in current or history of breast cancer)
Hypersensitivity to any component. Newborns or premature infants. Breastfeeding (contraindicated due to risk of adverse effects in infants). Concomitant use with MAOIs.
Breast cancer (current or history),Carcinoma of the endometrium or other estrogen-dependent neoplasia,Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease (current or history),Valvular heart disease with complications,Severe hypertension,Diabetes with vascular involvement,Headaches with focal neurological symptoms (e.g., migraine with aura),Major surgery with prolonged immobilization,Known or suspected pregnancy,Active liver disease or impaired liver function,Undiagnosed abnormal uterine bleeding,Hypersensitivity to any component,Cigarette smoking in women over 35 years of age
Avoid high-tyramine foods (aged cheese, cured meats, fermented products) if taking MAOIs. Grapefruit juice may increase phenylephrine absorption; limit intake.
No specific food restrictions. Grapefruit juice may slightly increase ethinyl estradiol levels but not clinically significant. High-fat meals do not affect absorption. Avoid excessive alcohol as it may impair compliance.
ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk from vasoconstrictive effects (phenylephrine) possibly reducing uterine blood flow; avoid if possible. Second/third trimester: phenylephrine may cause fetal hypoxia via placental vasoconstriction; use only if benefit outweighs risk. No known structural teratogenicity.
Pregnancy category X. Use contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects (e.g., VSD), neural tube defects, and cleft lip/palate. Second and third trimester exposure may cause fetal adrenal suppression, hepatic dysfunction, and virilization of female genitalia due to progestin component (levonorgestrel). Increased risk of ectopic pregnancy if conception occurs during use.
Brompheniramine is excreted in breast milk in small amounts; M/P ratio not established. Phenylephrine has minimal excretion. Due to anticholinergic effects, may reduce milk production or cause sedation in infants. Use caution; prefer non-sedating alternatives if possible.
Excreted in breast milk. Levonorgestrel M/P ratio approximately 0.3–0.4. Small amounts of ethinyl estradiol present. May reduce milk production and quality due to estrogen component. Use only if benefit outweighs risk; consider alternative contraception. American Academy of Pediatrics considers it compatible with nursing.
No specific pharmacokinetic studies. Increased plasma volume and renal clearance in pregnancy may reduce drug levels, but efficacy threshold remains. No dose adjustment recommended; use the lowest effective dose for shortest duration due to potential risks.
Contraindicated. No dose adjustments apply as drug must be discontinued immediately if pregnancy suspected or confirmed. Pharmacokinetic changes in pregnancy (increased clearance, volume of distribution) not relevant due to contraindication.
Actahist is a combination antihistamine-decongestant (chlorpheniramine/phenylephrine). Avoid in patients with hypertension, severe coronary artery disease, or MAOI use. Monitor for sedation and urinary retention, especially in elderly males with BPH.
ALESSE is a combined oral contraceptive (COC) containing ethinyl estradiol (20 mcg) and levonorgestrel (100 mcg). It is indicated for contraception and treatment of acne vulgaris in women aged ≥14. Monitor for thromboembolic events, especially in smokers >35 years. Assess for contraindications including migraines with aura, hypertension, and history of DVT/PE. Advise use of backup contraception if a pill is missed. Start on first day of menses or first Sunday after onset. Check BP at baseline and annually. Counsel on increased risk of VTE, especially in first year.
Take with food or milk to reduce stomach upset.,Avoid alcohol and CNS depressants as they can increase drowsiness.,Do not drive or operate machinery until you know how this medication affects you.,Contact your doctor if you experience chest pain, rapid heartbeat, or difficulty urinating.
Take one pill daily at the same time each day, even if you do not have sex.,Missed pill instructions: if late by <12 hours, take it as soon as remembered and continue schedule. If >12 hours, take missed pill (even if means taking two in one day) and use backup contraception for 7 days.,Possible side effects: nausea, breast tenderness, headache, breakthrough bleeding, especially in first 3 months.,Seek emergency care for signs of blood clot: leg pain/swelling, sudden chest pain, shortness of breath, severe headache, vision changes.,Do not smoke while on ALESSE, especially if over age 35, as it increases risk of serious cardiovascular events.,Inform your healthcare provider of all medications and supplements you take, as some (e.g., rifampin, anticonvulsants, St. John's wort) may reduce effectiveness.
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 ACTAHIST vs ALESSE, answered by our medical review team.
ACTAHIST is a Antihistamine that works by Antihistamine; binds to histamine H1 receptors, blocking the effects of histamine; also exhibits anticholinergic and mild sedative properties.. ALESSE is a Estrogen/Progestin Combination Contraceptive that works by Combination of ethinyl estradiol and levonorgestrel suppresses gonadotropin-releasing hormone (Gn RH) secretion from the hypothalamus, inhibiting pituitary release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), thereby preventing ovulation. Additionally, it thickens cervical mucus, impeding sperm penetration, and alters endometrial receptivity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACTAHIST and ALESSE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ACTAHIST is: 1.34 mg (one capsule) orally twice daily.. The standard adult dose of ALESSE is: One tablet (ethinyl estradiol 20 mcg, levonorgestrel 0.1 mg) orally once daily at the same time each day for 21 days, followed by 7 days of placebo. For initiation, start on the first day of menstrual period or first Sunday after onset of menses.. 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 ACTAHIST and ALESSE 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. ACTAHIST is classified as Category C. ACTAHIST (brompheniramine/phenylephrine) pregnancy category C. Inadequate human data; animal studies show no malformations at therapeutic doses. First trimester: theoretical risk f. ALESSE is classified as Category C. Pregnancy category X. Use contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects (e.g., VSD), neural tube defects, and cleft lip/palate. Seco. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.