Benzoyl Peroxide
Benzoyl peroxide (BPO) is acne therapy’s time-tested workhorse, straddling both antibacterial and keratolytic categories. The molecule comprises a peroxide bond flanked by two benzoyl groups; upon contact with skin, it splits into benzoic acid and free oxygen radicals. These radicals oxidize bacterial proteins, swiftly lowering Cutibacterium acnes populations without invoking the antibiotic resistance that plagues topical clindamycin or erythromycin. Simultaneously, the slightly acidic benzoic acid helps dissolve follicular keratin plugs, facilitating comedone expulsion.
Clinical efficacy is dose-responsive up to a point. A landmark meta-analysis found 2.5-percent BPO gel reduced inflammatory lesions by 54 percent after six weeks, while 10-percent gel achieved only marginally better clearance but doubled irritation rates. Hence, dermatologists often start patients at lower strengths, titrating upward only if necessary. Combining BPO with adapalene (a third-generation retinoid) boosts comedolysis, while the oxygen radicals synergistically mitigate antibiotic resistance when duet-ed with topical clindamycin.
Irritation – erythema, scaling, burning – is BPO’s Achilles’ heel. Formulators mollify it via polymerized delivery systems that embed BPO crystals in porous beads, releasing peroxide gradually. Moisturizing co-ingredients like niacinamide and panthenol further buffer against dryness. Still, users should phase in: apply every other night for a week before moving to nightly, and always layer a lipid-rich moisturizer after the gel dries.
BPO’s oxidative punch bleaches fabric and hair, so white pillowcases are your ally. Sunscreen remains obligatory not because BPO itself photosensitizes – it does not – but because peeling skin loses some of its natural UV defense. Salicylic acid cleansers pair well in the morning, sweeping away dead cells loosened overnight.
Notably, the FDA recently flagged rare but serious hypersensitivity events – hives, facial swelling – within minutes of application. Patch test on the inner forearm for three days before facial use. Pregnant individuals can use BPO; systemic absorption is negligible, and it is FDA pregnancy category C largely out of caution rather than documented harm.
In sum, benzoyl peroxide is akin to a diligent janitor: slightly harsh, unmistakably effective, and indispensable for keeping the pore “building” clean when hormonal tenants throw rowdy parties.
Benzoyl peroxide is a chemical compound (specifically, an organic peroxide) with structural formula (C6H5−C(=O)O−)2, often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as two benzoyl (C6H5−C(=O)−, Bz) groups connected by a peroxide (−O−O−). It is a white granular solid with a faint odour of benzaldehyde, poorly soluble in water but soluble in acetone, ethanol, and many other organic solvents. Benzoyl peroxide is an oxidizer, which is principally used in the production of polymers.
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 Skeletal formula (top) Ball-and-stick model (bottom) | |
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| Trade names | Benzac, Panoxyl, others |
| Other names | benzoperoxide, dibenzoyl peroxide (DBPO), BPO |
| AHFS/Drugs.com | Professional Drug Facts |
| MedlinePlus | a601026 |
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| Routes of administration | Topical |
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.002.116 |
| Chemical and physical data | |
| Formula | C14H10O4 |
| Molar mass | 242.230 g·mol−1 |
| 3D model (JSmol) | |
| Density | 1.334 g/cm3 |
| Melting point | 103 to 105 °C (217 to 221 °F) decomposes |
| Solubility in water | poor mg/mL (20 °C) |
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| Benzoyl peroxide (data page) | |
Benzoyl peroxide is mainly used in production of plastics and for bleaching flour, hair, plastics and textiles.
As a bleach, it has been used as a medication and a water disinfectant.
As a medication, benzoyl peroxide is mostly used to treat acne, either alone or in combination with other treatments. Some versions are sold mixed with antibiotics such as clindamycin. It is on the World Health Organization's List of Essential Medicines. It is available as an over-the-counter and generic medication. It is also used in dentistry for teeth whitening. In 2021, it was the 284th most commonly prescribed medication in the United States, with more than 700,000 prescriptions.
