I have successfully layered this over other primers and sunscreens before but honestly it is a 5 in one product meant to skip you steps and it is definetly hydrating enough on it's own.
I just use this over moisturizer and it has been great! I don't like a lot of layers! I have dry skin and this is not drying at all.
I'd try it alone, as it's so smoothly applied, and a separate sunscreen you could try is Peter Thomas Roth mineral powder sunscreen on top. But I've never had a sunburn, or greasy breakthru in any humidity, beach, or winter season. It's great when traveling, as it's so moisture sealing, yet super light and matte at the same time. They came out with a new version for acne and I just got a sample at the store tonight. I have all skin problems, blotchyness, acne, dryness, oilyness, and this product helps them all
This is truly an all in one product. Time saving and results perfect without layers of products.
I would use SPF under this product. I have dry skin, and thought this would be a good fit for both a primer and SPF. It does come off easily (wears off easily) taking the SPF with it. Not my fav product. Though it was great at first then noticed the silicone base just was too thick and easily rubbed off on everything and anything I touched to my face (sort of gross)