Quick Comparison
| Benzoyl Peroxide | Sulfur | |
|---|---|---|
| Typical Concentration | Concentrations: 2.5%, 5%, 10%. 2.5% is as effective as 10% for most people with significantly less irritation. Apply as a thin layer to acne-prone areas. Short-contact therapy (apply for 5-10 minutes then rinse) reduces irritation while maintaining efficacy. Bleaches fabrics — use white towels and pillowcases. | Concentrations: 2-10% in OTC products. Leave-on treatments: 3-8%. Wash-off: 5-10%. Can be used daily for mild acne. Sulfur masks (De La Cruz sulfur ointment) applied for 10-20 minutes are popular. Drying — follow with moisturizer. |
| Application | Topical (wash, gel, cream, spot treatment). Short-contact therapy: apply 2.5% for 5-10 minutes, then rinse — reduces irritation while maintaining antibacterial activity. | Topical (ointment, mask, cleanser, spot treatment). Leave-on or wash-off. Apply to clean skin. |
| Research Papers | 9 papers | 10 papers |
| Categories |
Mechanism of Action
Benzoyl Peroxide
Benzoyl peroxide decomposes on skin, generating benzoic acid and reactive oxygen species (peroxyl and hydroxyl radicals). Cutibacterium acnes is an obligate anaerobe thriving in oxygen-depleted follicles; BPO-derived oxygen creates an aerobic environment while free radicals cause non-specific oxidative damage to bacterial membranes, proteins, and DNA. Because this does not target a specific bacterial pathway (unlike antibiotics), C. acnes cannot develop resistance—BPO remains effective indefinitely. Mild comedolytic activity through oxidative effects on follicular keratin. Anti-inflammatory effects from neutrophil modulation. 2.5% achieves similar bacterial kill to 10% with less irritation.
Sulfur
Elemental sulfur (S8) reacts with cysteine residues in stratum corneum proteins to form hydrogen sulfide (H2S) and thiol derivatives, reducing disulfide bonds in keratin K1/K10 and cornified envelope — loosening corneocyte cohesion and promoting desquamation. Breaks hyperkeratotic plug in follicular ostia, unclogging pores. Bacteriostatic against Cutibacterium acnes through metabolism and membrane disruption. Reduces sebum production, possibly via anti-androgenic effects on sebaceous glands. Antifungal against Malassezia furfur (seborrheic dermatitis, pityrosporum folliculitis) via ergosterol synthesis inhibition. Anti-inflammatory effects may involve H2S signaling — endogenous H2S has vasodilatory properties. Mild comedolytic. Well-tolerated: works primarily on stratum corneum without deep penetration.
Risks & Safety
Benzoyl Peroxide
Common
Dryness, peeling, redness, bleaching of hair, towels, and clothing.
Serious
Allergic contact dermatitis (uncommon but can be severe — patch test first).
Rare
Severe allergic reaction with swelling.
Sulfur
Common
Drying, distinctive rotten-egg smell, may bleach fabrics.
Serious
None at cosmetic concentrations.
Rare
Allergic reaction (sulfur allergy is distinct from sulfonamide or sulfite allergy).
Full Profiles
Benzoyl Peroxide →
The most effective OTC acne treatment and one of the few topical treatments that kills acne-causing bacteria (C. acnes) without promoting antibiotic resistance. Benzoyl peroxide works through oxidation — it releases oxygen into pores, creating an environment where anaerobic bacteria cannot survive. It is one of three first-line acne treatments (alongside adapalene and salicylic acid) recommended by dermatological guidelines.
Sulfur →
One of the oldest acne treatments, used for centuries. Sulfur has keratolytic (exfoliating), antimicrobial, and anti-inflammatory properties that make it effective for acne, seborrheic dermatitis, and rosacea. It has a distinctive smell but is gentler than benzoyl peroxide and works well for people who cannot tolerate BP or salicylic acid. Often found in traditional 'sulfur soap' and spot treatments.