Retinol is highly effective. It is considerably less irritating and better tolerated than the prescription retinoid, Retin A (aka Tretinoin). It’s still a potentially irritating ingredient that is typically not tolerated by people with dry, sensitive, rosacea, or post-procedure skin.  Just because it is less irritating than its prescription counterpart, Retin-A/retinoic acid, that does not mean that it is good for everyone.
With high concentrations of retinol, there is some risk of redness, irritation, drying, and sun sensitizing. If you could not tolerate Retin A, start using Retinol just Monday, Wednesday, Friday at bedtime for first two weeks and then increase to nightly if well tolerated.
If you are new to retinol, use it sparingly to start with the aim of building a tolerance to it.
If your skin is sensitive, dry or rosacea prone, you might look for a more gentle version of retinol, called retinoic ester (used in the Dr. Loretta Concentrated Firming Moisturizer). Retinoic Ester is a great alternative for these skin types and is a key ingredient in the Dr. Loretta Concentrated Firming Moisturizer. It’s well tolerated by sensitive-skinned people and has been proven to support collagen, brighten skin and lessen pore appearance.