Is retinyl acetate as strong as retinol?

There is no basis for saying so. It sits one conversion step further out, and how much survives that step is not something the topical literature has settled.

Why use an ester at all?

Stability. Free retinol degrades in air and light, and an ester that survives the jar can be worth more in practice than a stronger molecule that does not.

Can I use it in pregnancy?

The standing advice is to avoid topical vitamin A derivatives in pregnancy. Ask the clinician looking after you rather than an ingredient list.

Will it make me peel?

It can, as any retinoid can, while skin adjusts. Two nights a week to start, a plain moisturiser alongside it, and stop if it stings rather than pushing on.

Does it cause sun sensitivity?

Vitamin A derivatives break down in light and skin using them tends to be less tolerant of sun, which is why they are night products and why sunscreen the next morning is part of the routine.

Retinyl Acetate — Ingredient Guide

How it works

Nothing in a skin cell responds to retinyl acetate. What cells respond to is retinoic acid, and the route to it is a chain: the ester has to be cut to give retinol, retinol has to be oxidised to retinaldehyde, and retinaldehyde has to be oxidised once more. Retinyl acetate joins that chain at the top, so it has one more step to clear than retinol and two more than retinaldehyde.

The cutting is done by the skin's own esterases, which sit mainly in the living epidermis rather than in the dead surface layer. The molecule therefore has to get past the surface before there is anything present to convert it, and every step after that is another place for the dose to get smaller.

The evidence

This is the part the marketing tends to walk past. The substantial human topical literature on vitamin A is on tretinoin, on retinol and on retinaldehyde. For retinyl acetate specifically the published topical record is thin, and much of what circulates is inference from retinol plus supplier data.

The practical consequence is simple: do not read a retinol percentage across. Two products can carry the same number and deliver very different amounts of retinoic acid, because the number describes what went into the jar rather than what the skin managed to make of it. The ester is chosen because it holds up better in air and light than free retinol does, which is a genuine advantage in something a person will own for months. It is not an advantage in strength, and a retinoid that feels milder is usually milder in both directions.

Suitability

It is a retinoid and the ordinary retinoid cautions apply: dryness, flaking and irritation while skin adjusts
Use it at night and wear sunscreen the next morning, as with any vitamin A derivative
Topical vitamin A derivatives are generally avoided in pregnancy and while trying to conceive — a conversation for a clinician rather than for a label
Two nights a week to begin with, building slowly, and stop rather than push on if the skin is stinging

Concentration

No figure is given. There is no established effective topical concentration for this ester; the percentages in circulation were measured on retinol. Cosmetic limits on vitamin A are market-specific and have been under revision, so the current local rule is the thing to check rather than a number written here.

Conflicts & combinations

Benzoyl peroxide is the real chemical conflict. It is an oxidiser and retinoids are exactly what it will oxidise, so the two want separate applications rather than the same layer. The much-repeated conflict with acids is different: the problem is cumulative irritation from two demanding steps at once, not a reaction in the bottle, and spacing them out solves it. Pair it instead with the dull, useful things — a plain moisturiser, and sunscreen in the morning.