Retinol and retinoid sound so similar, its easy to think they are the same thing. Not really. Retinoids , available only by prescription, have been proven to change aging skin, starting deep in the lower layers of the skin. Countless studies have shown that retinoids can both prevent and reverse UV damage, increase circulation and reduce aging inflammation. Because retinoids make organic changes in the skin they can unwanted albeit temporary problems including flaking and redness.
By contrast retinols are a much milder form of retinoids. Applied to the surface of the skin, they slowly are converted into true retinoids, but at a much lower concentration. The good news is that are much less irritating. The bad news? They produce less dramatic improvements. I have read that retinols have about 1/4 the strength of retinoids. This means that a .4% Retinol is equal to a .1% Retinoid. However most of the drug and department store products with retinol don’t share how much retinol they contain. You can’t tell if there is just a tiny drop in a big vat or is strong enough to make a real difference to your skin.
There are few products that reveal their retinol concentrations. Retinol.5% from Skinceuticals has .5% retinol ( $50). Avene Retinol.1 Cream( $64) has, like the label says, .1% retinol. This is about equal to .025% retinoid which is the strength of Renova, the mildest formulation of Retin A.