Hi Dr Irwin,
I am sorry for bothering you with this question yet again, but it is almost impossible
to get a definitive answer to it. If I apply sunscreen/block first, as is recommended by some, will other products applied on top of it have any effect at all or would they even decrease the effectiveness of the sunscreen. Dr. Neil Schultz of Dermtv argues that sunscreen should go on first whereas Paula Begoun totally disagrees with him and says it can be applied last. These are two people whose opinion I greatly admire and it is frustrating when they seem to be at loggerheads on this question. I use Paula's Choice Serum and Moisturiser. After washing my face, these two products would go on first and then my sunscreen. But now I am not sure what to do. I emailed Dr. Schultz and he said that the most important product to apply in the morning is sunscreen and he suggested using serums, etc at night. But I use Retin-A at night along with TNS Recovery Complex and might be over complicating things by adding serums and moisturisers. I really think you would be doing many people a huge favour if you could shed some light on what the best thing is to do. There is a lot of confusion in many of the skin sites I visit about this important skin topic. Thank you so very much!
You’re right – this is confusing and there isn’t any data on this. Here’s my take on it and here’s link to more questions on products – see the answer about half way down from April 12, 2012.
If your sunscreen is primarily a chemical block, then it needs to bind to cells to work well so put it on first and then your antioxidant over it. If your sunscreen is primarily a physical/mineral block then it doesn’t matter and it’s better to put the antioxidant on first and then the sunscreen. You’ll get a little more out of the antioxidant.
You have a good regimen at night by using the TNS first and putting the Retin-A over that. Let that all sink in for 5-10 minutes. You can always put a little moisturzer on then if needed. If you get irritated easily with the retinoids or are dry, then use the TNS, then a light moisturzer, wait 10 min and then use the Retin-A. Hope this helps, Dr. I