Whether you’re looking to smooth texture, clear up acne, reduce fine lines, or lighten dark spots, retinol can help. However, not everyone should use the same retinol formula: some skin types can tolerate high-performance products, while others should opt for milder ones.

But no matter which retinol you swear by, there’s one thing you should know: Retinol doesn’t mix well with all skin care ingredients out there. Here we highlight a few that you should never mix with this active as well as others that fit perfectly.