I love being practical and all, so it is clear that I love combination products, too. Make up containing sunscreen is a perfect example, since there are fewer layers to apply, less time needed to get it done and SPF protection, which is a must for your skin always!...
But, is the sun protection offered by the SPF containing make up, enough to protect your skin? Is the sun protection we get really up the alley, or are we just being fooled?
Actually, it is none of the above... Keep in mind the golden rule that insufficient amounts of sunscreen, causes the SPF to fall dramatically to the root of the labelled SPF on the product bottle. So let's say we have a foundation marketed with an SPF of 15. If insufficient amounts of the product are used, the SPF will be the square root of 15, being reduced to 4, and SPF 50 will be reduced to 7!
If this isn't enough, there are a lot neglected areas when we put make up on... Even the amount of make up we put on tends to be minimal, to avoid the cakey face, or the clown face...
Do you apply your make up uniformly and in the right amount needed to attain the goodies of the labelled sunscreen? Also a lot of make up contains protection just against UVB rays, so against sunburn.
Since both UVA and UVB are harmful, you need protection from both kinds of rays. Do not forget that UVA rays are long ultraviolet rays, known to cause premature aging of the skin and skin cancer. If you want to spot a make up that has UVA protection, it must be labellet "UVA protection", or "Broad spectrum protection".
It doesn't mean that just because your make up has SPF it will give you the sun protection you need. So do not rely solely on your make up for your sun protection. Or, use it uniformly, in generous amounts and everywhere that you need protection. Be aware that it must contain UVA protection as well.
Otherwise just use a broad spectrum SPF containing cream underneath your make up. If you do this, it's hard to tell how a sunscreen will react with another sunscreen, unless you know specifically what the active ingredients are, and how they would react with each other. But we aren't all PhD holders.
So the easiest way is to just have only ONE product with SPF in your routine and apply that properly. That way, you can be sure it won't have any other sunscreen ingredients to interfere with its effaciacy. Don't get a moisturizer with SPF, a foundation with SPF, and try to layer them both with a sunscreen. That's just a waste of all that sun protection in the product.
If I were you I would get just a cream with broad spectrum SPF and no SPF make up...
Stay well!