Differin

Differin is a prescription (and in some strengths, pharmacy-available) topical medicine containing adapalene, a third-generation synthetic retinoid used for the treatment of mild to moderate acne vulgaris in adults and adolescents from the age of 12. It is available as a 0.1% gel, 0.3% gel, and 0.1% cream. Adapalene is applied once daily at night to affected areas and represents one of the most well-evidenced topical retinoids available, with a large body of clinical trial data supporting its efficacy and a more tolerable skin irritation profile compared with earlier retinoids such as tretinoin.

How Differin Treats Acne

Acne vulgaris develops when a combination of factors — excess sebum production, abnormal follicular keratinisation, colonisation by Cutibacterium acnes (formerly Propionibacterium acnes), and local inflammation — conspire to block and inflame hair follicles. Adapalene addresses several of these pathogenic processes simultaneously.

Mechanism of Action

Adapalene acts as a selective modulator of retinoic acid receptors (specifically RAR-beta and RAR-gamma) within the epidermis and follicular epithelium. By binding to these nuclear receptors, it regulates the transcription of genes involved in epidermal cell differentiation and turnover (keratinisation). The result is normalisation of the follicular keratinisation process, reducing the abnormal build-up of dead skin cells within the pilosebaceous unit that forms the primary acne lesion — the comedo. This anti-comedogenic action prevents new comedones (blackheads and whiteheads) from forming and helps resolve existing ones.

Adapalene also exerts significant anti-inflammatory effects by modulating the activity of nuclear receptors involved in the inflammatory response, reducing leukocyte migration into follicles and decreasing the expression of pro-inflammatory cytokines. These dual comedolytic and anti-inflammatory actions make Differin effective for both non-inflammatory (comedonal) and inflammatory (papular and pustular) acne.

Differin is applied topically to the face and/or other affected areas (back, chest) once daily in the evening, after cleansing and ensuring the skin is dry. A thin layer should be applied to the entire affected area rather than just to individual spots, as adapalene works best when applied as a preventative treatment across the follicular units at risk of comedone formation.

Application Technique

Wash the face gently with a mild, non-comedogenic cleanser and pat dry. Wait 20-30 minutes before applying Differin if the skin is sensitive, as applying retinoid to damp skin increases penetration and may worsen irritation. Apply a pea-sized amount of gel or cream to the fingertips and spread thinly and evenly over the affected area. Avoid the corners of the mouth, nostrils, and eyes, where the skin is thin and particularly prone to irritation.

Initial Purging and Adjustment Period

Patients should be counselled about the likelihood of an initial "purging" phase in the first four to eight weeks of treatment, during which acne may appear to worsen before it improves. This reflects the accelerated turnover of microcomedones that were already forming beneath the skin surface. This is a normal and expected part of the treatment response and does not indicate that Differin is unsuitable. Reassurance and encouragement to persist with treatment are important to prevent premature discontinuation.

Sun Protection

Adapalene increases skin sensitivity to ultraviolet light. Daily use of a broad-spectrum SPF 30 or higher sunscreen is essential during treatment, even in cloudy conditions. Prolonged direct sun exposure should be minimised, and protective clothing should be worn where possible.

Differin should be applied once daily in the evening to clean, dry skin. The standard starting formulation is 0.1% gel or cream. If the patient has not achieved adequate improvement after 12 weeks of the 0.1% formulation, the clinician may consider switching to Differin 0.3% gel.

Clinical guidelines generally recommend a minimum treatment duration of 12 weeks before assessing full efficacy, as the comedolytic and anti-inflammatory effects of topical retinoids develop over time as follicular turnover normalises. Maximum benefit is typically achieved at 16-24 weeks. Once acne is well controlled, a maintenance regimen using Differin two to three times per week, rather than daily, can be considered to sustain remission and minimise irritation.

Differin should not be used in children under 12 years. No dose adjustment is required based on age in adolescents or adults. In patients with very dry or sensitive skin, starting with every-other-night application and building up gradually to nightly use can improve tolerability.

Differin is generally better tolerated than older topical retinoids, but local skin reactions are common, particularly during the initial weeks of treatment.

Common Side Effects

• Skin dryness, scaling, or peeling — most pronounced in the first four to six weeks, typically improving as the skin adapts
• Erythema (redness) at the application site
• Burning, stinging, or tingling sensation after application, particularly on first use
• Pruritus (itching) at the application site
• Photosensitivity — increased susceptibility to sunburn with UV exposure

Serious Side Effects

Serious adverse effects with topical adapalene are uncommon given its minimal systemic absorption. However:

• Severe irritation or eczematisation: if significant inflammation, blistering, or weeping develops at the application site, Differin should be discontinued temporarily and the skin managed with an emollient or, if indicated, a mild topical corticosteroid under medical supervision; reintroduction at a lower frequency may be possible once the skin has recovered
• Allergic contact dermatitis: although rare, sensitisation to adapalene or excipients can occur; persistent or worsening inflammation distinct from expected irritation should be assessed by a dermatologist
• Worsening of acne beyond the expected purging phase: if acne continues to deteriorate significantly beyond eight weeks without any sign of improvement, clinical reassessment is warranted

Differin should be used with care and patients should be well informed about both the expected adjustment period and the precautions necessary to minimise adverse effects.

Photosensitivity and Sun Care

Adapalene increases the skin's sensitivity to UV radiation, making daily sun protection essential. Patients must be instructed to apply a broad-spectrum SPF 30+ sunscreen every morning and to reapply after sweating or swimming. Sunbeds, sunlamps, and other sources of ultraviolet radiation should be avoided during treatment. Patients who develop sunburn should avoid using Differin until the skin has fully recovered.

Concurrent Use of Irritating Skin Products

Differin should not be used simultaneously with other potentially irritating topical preparations, including other topical retinoids, benzoyl peroxide (if causing significant irritation), alcohol-based astringents, or abrasive cleansers. These combinations can significantly exacerbate dryness, peeling, and erythema, particularly during the initial weeks of treatment. Benzoyl peroxide can be used with adapalene as part of a combination regimen, but if irritation is problematic, the two should be applied at different times of day (adapalene in the evening, benzoyl peroxide in the morning).

Pregnancy and Contraception

Differin must not be used during pregnancy, as retinoids are associated with teratogenicity. Although systemic absorption from topical adapalene is minimal, the retinoid risk class means that women of childbearing potential should use effective contraception during treatment. If pregnancy occurs during treatment, Differin should be stopped immediately.

Differin must not be used in the following situations:

• Known hypersensitivity to adapalene or any excipients in the formulation
• Pregnancy or women actively trying to conceive
• Breastfeeding (avoid application to the breast or chest area)
• Eczematised, sunburned, or broken skin at the application site
• Application to mucous membranes, including lips, nostrils, and eyes
• Concomitant use with other topical retinoids (e.g., tretinoin, tazarotene)
• Use in children under 12 years of age
• Patients with severe eczema or dermatitis at the intended site of application