Retinol

How it works, mechanically

Skin cannot use retinol directly. It has to convert it, step by step, into retinoic acid, which is the form that is actually active. Each conversion step loses material, so a retinol product delivers considerably less active than a prescription retinoid of the same nominal strength. That inefficiency is the whole reason retinol is available without a prescription: it is slower and gentler because most of it never becomes active at all.

• A conversion chain. Retinol to retinaldehyde to retinoic acid, with losses at each stage.
• Slower than a prescription retinoid. That is the deliberate trade.
• Concentration is not comparable across brands. Percentage alone tells you little without knowing the form and the formula around it.

The schedule is the instruction

Starting daily is the most common mistake, and it ends most retinol routines within 14 days. The usual approach is twice a week for the first 2 to 3 weeks, then every other night, then daily only if the skin has stayed comfortable throughout. Dryness, flaking and tightness in the first weeks are well documented and are a signal to slow down rather than to push on.

• Begin at twice a week. Increase only after some weeks without irritation.
• Night only. Retinol degrades in light and increases sensitivity to it.
• Daily sunscreen while using it. Photosensitivity is the best established practical consequence of using it at all.
• Do not stack it with acids on the same night. Combining actives is where most avoidable irritation comes from.

Who should ask a doctor first

This part is not a formality. Every retinoid carries a pregnancy caution, and while the evidence on low strength topical retinol differs from the evidence on oral or prescription retinoids, the standard advice is to skip it while pregnant or nursing until a doctor clears it. Anyone using a prescription skin treatment, or managing a diagnosed condition, should also raise it before adding this to a routine.

• Pregnant or breastfeeding. Ask a doctor before using any retinoid, including a cosmetic strength one.
• On prescription skin treatment. Interactions are a matter for whoever wrote the prescription.
• Sensitive or compromised skin. Broken, sunburned or actively irritated skin is not where to begin.
• Nothing here is medical advice. This is a description of how a cosmetic ingredient is normally used, and a doctor's answer overrides it.

Body retinol is not face retinol

Something worth flagging plainly: retinol body care is made for the chest, the backside and other areas of thicker skin, not for the face. Retinol is far better known as a facial ingredient, so if you have read about it before, that reading was almost certainly about a different application on much thinner skin.

• Body formats vary. Butters, scrubs and serums all carry it, made for the chest or aimed lower.
• Rinse-off is gentler. A scrub is rinsed away within minutes while a butter or serum stays on for hours, so leave-on formats deserve the strictest schedule.
• Body skin is not face skin. It is thicker and generally more tolerant, but the schedule and the cautions above still apply.
• The base matters too. For what the retinol is carried in, see the whipped body butter and sugar scrub pages.