SELSUN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SELSUN (SELSUN).
Selenium sulfide is an antifungal agent that inhibits the growth of Malassezia species by reducing selenium to elemental selenium, which is toxic to the fungus. It also reduces sebum production via unknown mechanisms.
| Metabolism | Selenium sulfide is not significantly absorbed through intact skin; systemic metabolism is negligible. If ingested, selenium undergoes hepatic methylation and renal excretion. |
| Excretion | Selenium sulfide is minimally absorbed; absorbed portions are excreted renally (approx. 80-90%) and fecally (10-20%). |
| Half-life | Not well defined due to minimal systemic absorption; topical application yields negligible plasma levels. |
| Protein binding | Not clinically applicable due to negligible systemic absorption; no data available. |
| Volume of Distribution | Not applicable; negligible systemic distribution after topical application. |
| Bioavailability | Topical: <1% absorbed through intact skin; higher absorption through damaged skin but still minimal. |
| Onset of Action | Topical: Improvement in dandruff/seborrheic dermatitis seen within 1-2 weeks of regular use. |
| Duration of Action | Therapeutic effect persists for 1-4 weeks after cessation of regular use, depending on condition severity. |
| Molecular Weight | 222.15 |
Apply 5-10 mL of 2.5% selenium sulfide lotion to affected areas of scalp, lather with water, leave on for 2-3 minutes, then rinse thoroughly. Use twice weekly for 2 weeks, then once weekly for maintenance.
| Dosage form | LOTION/SHAMPOO |
| Renal impairment | No dosage adjustment required for topical use. |
| Liver impairment | No dosage adjustment required for topical use. |
| Pediatric use | Children <5 years: not recommended. Children ≥5 years: same as adult dosing. |
| Geriatric use | No specific adjustment required; use with caution due to potential skin fragility and apply only to intact skin. |
| 1st trimester | Limited human data; animal studies show no teratogenic effects. Avoid first trimester unless benefit outweighs risk. |
| 2nd trimester | Limited human data; no known fetal harm from topical use. Avoid prolonged use on large areas. |
| 3rd trimester | Limited human data; no known fetal harm from topical use. Avoid prolonged use on large areas. |
Clinical note
Comprehensive clinical and safety monograph for SELSUN (SELSUN).
| Placental transfer | Negligible systemic absorption from topical application; not expected to cross placenta significantly. |
| Breastfeeding | Minimal systemic absorption with topical use; unlikely to reach significant levels in breastmilk. Use caution if applied to large areas or broken skin. |
| Lactation Rating |
■ FDA Black Box Warning
Avoid contact with eyes; if accidental contact occurs, flush with large amounts of water. Do not use on broken skin or areas with open wounds.
| Serious Effects |
Hypersensitivity to selenium sulfide or any component of the formulation
| Precautions | External use only; avoid contact with eyes, mucous membranes, and broken skin., May cause skin irritation or allergic contact dermatitis., Discontinue if excessive irritation or sensitivity occurs., Use with caution in patients with pre-existing skin conditions or compromised skin barrier. |
| Food/Dietary | No clinically significant food interactions. Avoid alcohol consumption during treatment for seborrheic dermatitis? Not applicable. Selenium sulfide is not known to interact with dietary components. |
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| L3 - Moderately Safe |
| Teratogenic Risk | FDA Pregnancy Category C. Selenium sulfide is not systemically absorbed significantly after topical application. Animal studies have not been conducted; potential fetal risk is unknown but expected low due to minimal systemic absorption. No known teratogenicity from topical use. Avoid prolonged use on large body areas during pregnancy. |
| Fetal Monitoring | No specific monitoring required due to low systemic absorption. Monitor for local skin reactions. In case of accidental ingestion, monitor for selenium toxicity (garlic breath, nausea, alopecia, nail changes). |
| Fertility Effects | No known effects on fertility from topical selenium sulfide. Systemic toxicity from excessive absorption could theoretically impair fertility, but this is unlikely with proper topical use. |
| Clinical Pearls | Selsun (selenium sulfide) 2.5% lotion or shampoo is a first-line topical antifungal for seborrheic dermatitis and tinea versicolor. It has cytostatic activity on epidermal cells, slowing turnover. For tinea versicolor, apply to entire trunk and proximal extremities, avoiding mucous membranes. Use for 10 minutes before rinsing, daily for 7 days. For seborrheic dermatitis, use twice weekly. May cause hair discoloration or dryness; counsel patients with chemically treated hair. Avoid contact with eyes and genitalia. |
| Patient Advice | Shake the bottle well before use. Apply to wet hair or affected skin, leave on for 10 minutes (shampoo) or as directed (lotion), then rinse thoroughly. · For tinea versicolor, apply to entire trunk and arms, avoiding genital and anal areas. Use daily for 7 days. · May cause temporary hair discoloration (especially on white, gray, or chemically treated hair). Test on a small area first. · Avoid getting product in eyes, mouth, or broken skin. If contact occurs, flush with water for 15 minutes. · Do not use on inflamed or weeping lesions. Discontinue if irritation develops. · Wash hands thoroughly after application. Rinse all product from skin and hair to prevent staining. · Do not use more often than directed; overuse can increase side effects. |