What adapalene is — and why it is the retinoid most worth starting with.

Adapalene is a synthetic retinoid — a vitamin A derivative — and it is, by a significant margin, the most accessible prescription-grade retinoid now available without a dermatologist. In Australia, 0.1% adapalene (sold as Differin and its generics) is available over the counter. The clinical literature behind it is substantial. The misunderstanding around it is equally substantial.

This is what adapalene is, what it does, and what to know before adding it to a routine.

What makes adapalene different from retinol

Retinol, retinaldehyde, and tretinoin are all forms of vitamin A that follow the same basic conversion pathway in the skin. Retinol is converted to retinaldehyde, which is converted to retinoic acid — the biologically active form that produces effects at the cellular level. The further a compound sits from retinoic acid in this chain, the more conversion steps are required, which generally means slower onset and lower irritation.

Adapalene is structurally different. It is a naphthalene-based compound, not a direct retinol analogue, and it does not undergo the same multi-step conversion. Instead, it selectively binds to specific retinoic acid receptors — particularly RAR-β and RAR-γ — while largely avoiding the RAR-α receptor associated with irritation. This receptor selectivity is clinically relevant: adapalene is significantly better tolerated than tretinoin at comparable therapeutic concentrations, with clinical trials showing lower rates of erythema, scaling, and dryness. It is also photostable — unlike tretinoin, it does not degrade in light, which makes morning use possible, though evening is still the standard recommendation.

What adapalene does in the skin

The primary mechanism of adapalene is normalising follicular keratinisation — the process by which keratinocytes lining the follicle differentiate and shed. When this process is disrupted, the follicle fills with keratinised cells and sebum, forming a comedone. Adapalene corrects the underlying cellular process, not just the visible outcome.

This is why adapalene is particularly effective for comedonal acne — closed and open comedones — rather than only inflammatory lesions. Many spot treatments target the bacteria involved in inflamed pustules; adapalene targets the reason the follicle was blocked in the first place.

Beyond acne, adapalene has a growing body of evidence for fine lines, skin texture, and early photoageing — mechanisms shared with tretinoin, driven by retinoic acid receptor activation and downstream effects on collagen synthesis and epidermal cell turnover. It is increasingly considered a first-line anti-ageing ingredient alongside its established role in acne.

How to introduce adapalene

The introduction protocol mirrors retinol: start slowly and build.

Begin at two or three evenings per week, applied to clean, fully dry skin. A pea-sized amount for the entire face is sufficient. Apply moisturiser over the top — this does not reduce efficacy, and it meaningfully reduces the dryness and flaking that most people experience in the first four to six weeks.

The adjustment period is real and predictable. Retinisation — the skin's response to the initial increase in cell turnover — produces temporary dryness, flaking, and sometimes purging as follicular contents are accelerated to the surface. This is the expected response. The window is typically four to six weeks; after that, the skin adjusts and tolerability improves.

After four weeks of twice-weekly use without significant irritation, frequency can increase to every other night. After another four weeks of tolerance, nightly use becomes the target maintenance frequency.

What not to layer with adapalene

The combination to avoid is adapalene with high-strength exfoliating acids on the same evening. Retinoids increase cell turnover; AHAs and BHAs increase surface exfoliation. Applied together at full frequency, the combined irritation load can compromise the barrier. The simplest approach: use exfoliating acids on the nights adapalene is not used, or reduce acid frequency during the retinisation adjustment period.

Vitamin C — particularly L-ascorbic acid in low-pH formulations — is best reserved for the morning, leaving adapalene for the evening.

Niacinamide is compatible with adapalene. Applied before or after, it supports barrier function and tolerability throughout the adjustment period.

The case for adapalene as a first retinoid

For people considering introducing a retinoid — whether for acne, texture, or anti-ageing — adapalene at 0.1% is the most sensible starting point. The clinical evidence matches or exceeds retinol at equivalent concentrations, the tolerability profile is better than tretinoin at comparable clinical effect, it is photostable, and it is now widely available without a prescription.

The protocol for success is the same as with any retinoid: start slowly, support the barrier, and stay consistent past the adjustment period.