Actives glossary
Retinaldehyde
One conversion step from retinoic acid instead of two, which is the whole argument for using it.
- INCI name
- Retinal
- Also called
- retinal, vitamin A aldehyde
- Family
- Retinoid
- Range seen on labels
- 0.05% to 0.2%
- Sits well with
- niacinamide, ceramides
- Needs care with
- glycolic-acid, salicylic-acid, tretinoin
Retinaldehyde sits one step closer to retinoic acid than retinol does. Skin converts it directly, which is why a 0.1% retinaldehyde and a 0.5% retinol can be discussed in the same breath even though the numbers look a factor of five apart.
Why the percentages look low
Because the conversion is shorter, less material is needed. A retinaldehyde product at 0.05% is not a weak product, and comparing it to a retinol percentage as though the units were the same is the most common mistake in this category. Any ranking that sorts retinoids purely by the number on the front of the box is sorting by the wrong column.
The colour tell
Retinaldehyde is yellow. Products that contain a meaningful amount of it usually are too, and a retinaldehyde serum that is water-white is worth a second look. This is a rough signal rather than a measurement, and it is not a substitute for a published percentage.
Tolerance
The comparative work that exists puts retinaldehyde’s tolerance closer to retinol than to prescription retinoic acid, at doses that produce comparable appearance changes. That is a useful thing to know when picking a first retinoid, and it is a statement about irritation reports in study conditions rather than a promise about any individual face.