> ## Documentation Index > Fetch the complete documentation index at: https://docs.hi-doctor.ai/llms.txt > Use this file to discover all available pages before exploring further. # Benzoyl peroxide — how it works in acne > An oxidising antibacterial that does not select for resistance. How benzoyl peroxide works, why it bleaches fabric, and why it is paired with other agents. Benzoyl peroxide is one of the oldest topical acne treatments still in routine use, and it has survived because nothing has replaced what it does. It is an oxidising agent with antibacterial, anti-inflammatory and mildly comedolytic activity, and — uniquely among antibacterials used in acne — organisms do not develop resistance to it. ## What it is Active ingredient: **benzoyl peroxide**. On this service it is not prescribed alone. It appears in two fixed combinations on the [acne](/library/conditions/acne) pathway: with [adapalene](/library/medicines/adapalene) 0.1% at **2.5%**, and with [clindamycin](/library/medicines/clindamycin-topical) 1% at **3% or 5%**. In the EU the clindamycin combination is marketed under brand names including Duac, and the adapalene combination as Epiduo or Acniduo. ## How it works In the follicle it decomposes to release free-radical oxygen, which oxidises bacterial proteins non-specifically. Because the mechanism is chemical damage rather than interference with a specific enzyme, there is no target for an organism to mutate — which is why resistance to benzoyl peroxide has not emerged. Pairing it with a topical antibiotic reduces the emergence of resistant *Cutibacterium acnes*. This is not a marketing pairing — it is the reason topical clindamycin is not supplied on its own. It reduces the inflammatory response around the follicle, which is why inflammatory papules and pustules respond to it faster than comedones do. It has some keratolytic effect on the follicular plug, though considerably less than a retinoid. This is why it is combined with one rather than used to replace it. ## The bleaching, in advance **Benzoyl peroxide permanently bleaches fabric, towels, bedding, hair and eyebrows.** It oxidises dye. The damage is not a stain that can be washed out — the colour is destroyed. White pillowcases and white towels, and letting the product dry fully before dressing or going to bed, are the standard ways round it. Hair contact bleaches hair; that includes beards and eyebrows. This is the single most common avoidable complaint about benzoyl peroxide, and it is entirely preventable by being told first. ## What has been reported | Reported effect | Character | | ---------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Dryness, scaling and peeling | Very common, particularly at the higher strength and in the first weeks | | Burning or stinging on application | Common early; usually settles | | Erythema and irritation | Common; disproportionate redness or swelling is a reason to stop | | Allergic contact dermatitis | Uncommon but well documented. It differs from ordinary irritation by being intensely itchy, spreading beyond the application area and worsening rather than settling | | Photosensitivity | Reported; daily broad-spectrum sun protection is part of the routine | | Fabric and hair bleaching | Expected, permanent, and covered above | Higher strength is not proportionally better. Comparative work in acne has generally found little additional benefit from stronger benzoyl peroxide preparations, while irritation rises steadily with concentration. Which strength is appropriate is a decision the reviewing doctor makes. ## Realistic timelines Dryness and peeling begin. The most irritating period, and the one that reduced application frequency exists for. Inflammatory lesions usually respond before comedones do, so the redness settles before the texture does. The fair point of assessment for the combination as a whole. Continued use maintains the antibacterial and resistance-suppressing effect. Where a topical antibiotic is part of the combination, benzoyl peroxide is not the component to drop. ## Who it is not suitable for Anyone with known hypersensitivity to benzoyl peroxide or to an excipient in the formulation, and anyone who has previously had a true allergic contact dermatitis to it. It is not applied to broken, eczematous or sunburnt skin. Suitability in pregnancy and breastfeeding is a decision for the reviewing doctor, who needs to know before prescribing. ## How Hi-Doctor handles it The consultation is fully asynchronous — there is no video call and no telephone consultation. You answer the acne questionnaire, upload a photograph, and a registered doctor reviews the case and decides which combination, if any, is appropriate. A prescription is never guaranteed; if one is not issued the consultation fee is refunded in full. The medicine is dispensed and paid for at a pharmacy of your choosing — see the [pricing page](/essentials/pricing) for what the consultation fee covers. ## Related reading * [Acne](/library/conditions/acne) * [Adapalene](/library/medicines/adapalene) · [topical clindamycin](/library/medicines/clindamycin-topical) · [azelaic acid](/library/medicines/azelaic-acid) * [How to apply a prescription topical](/library/guides/how-to-apply-topicals) * [Side effects of dermatology topicals](/library/guides/side-effects-dermatology) * [Safety and eligibility](/essentials/safety) ## Start a consultation Answer the acne questionnaire, upload your photos, and a registered doctor reviews the case. They decide whether a topical treatment is appropriate and which one — declining is a normal outcome. See [what it costs](/essentials/pricing) and [how the review works](/essentials/how-it-works). This page is reference information, not medical advice and not a prescription. Whether a medicine is appropriate for you is decided by a registered doctor after reviewing your consultation.