Retinal

Retinal, listed on ingredients labels as Retinaldehyde, is a form of vitamin A that sits one rung above retinol in the retinoid family. Chemically it is the intermediate stage between retinol and retinoic acid, which is the form the skin can actually use. That position is the whole point of it.

Because retinal is already one step further along, the skin has only a single conversion to perform rather than two. Less is lost along the way, so useful amounts are reached at much lower percentages than retinol requires. Products typically sit between 0.01% and 0.1%, and a 0.05% retinal is not a weak product simply because the number looks small next to a 0.5% retinol.

It is a comparatively recent arrival on shop shelves, largely because it is awkward to work with. Retinal is even more sensitive to light and air than retinol, and it carries a natural yellow-orange colour that can tint a cream. Well-made products are packaged in opaque, airless containers, and a change from pale gold to deep brown suggests the product is past its best.

In practice it appears in night serums and night creams aimed at the look of fine lines, uneven tone, rough texture and congestion. It tends to appeal to people who want more than a gentle retinol offers but have found higher-strength retinol uncomfortable.

It is worth being clear about where retinal sits. It is not a prescription product, and it is not simply a stronger retinol. It occupies the ground between the two: closer to the active form than retinol, but still an over-the-counter cosmetic ingredient with the tolerance profile that implies. For most people it is a step to consider once a retinol routine is established and comfortable, rather than a starting point.

Every retinoid has to become retinoic acid before skin cells can respond to it. Retinol needs two enzyme conversions to get there. Retinal needs one. Fewer steps means less of the applied dose is lost on the way, which is why comparatively tiny percentages of retinal behave like much larger percentages of retinol.

Once retinoic acid is present, the mechanism is the same across the whole family. It binds to receptors inside skin cells that influence gene activity, and through that it adjusts how quickly surface cells are replaced, how evenly pigment is distributed through the upper layers, and how much of the supporting structure beneath is produced and maintained. It is a signalling ingredient, not an exfoliant, even though the eventual effect on texture can look similar.

Retinal is also unusual among retinoids in having some direct antimicrobial activity of its own, independent of the conversion route. That is part of why it is often chosen for skin that looks congested as well as ageing. Its shorter conversion path can mean visible change arrives a little sooner than with retinol, though the same broad expectation applies: think in terms of two to three months of consistent use, not weeks.

Retinal is used in the same way as retinol, but the numbers on the bottle mean something different, so read them on their own terms.

• Night only, on clean, completely dry skin. Retinal degrades in daylight.
• Do not translate percentages across. 0.05% retinal is a meaningful strength. Comparing it with 0.5% retinol and assuming it is ten times weaker is the most common mistake people make.
• Start low and infrequent: 0.01–0.05%, two or three nights a week, building up as skin settles.
• Order in the routine: cleanse, watery products, retinal, then moisturiser. Buffering with moisturiser first is a reasonable way in for sensitive skin.
• Pairs well with niacinamide, ceramides, panthenol, squalane and hyaluronic acid.
• Keep apart from exfoliating acids, benzoyl peroxide and scrubs on the same night. Use them on alternate evenings.
• Do not stack retinoids. Retinal, retinol and a prescription retinoid in the same routine is a route to a compromised barrier, not faster results.
• SPF 30 or above every morning, without exception.
• Watch the colour. Retinal is naturally yellow-orange; if a product darkens noticeably or smells sharp, replace it.

Expect the first few weeks to involve some dryness. Persistent stinging, tightness or soreness means you are going too fast.