I've been reading up on the topic of UVA/UVB protection recently in prep for the spring/summer and having just been diagnosed with Rosacea, wanted to ensure no (or little) further skin damage or Rosacea flare-ups occured.
It would appear that at least some Rosaceans tolerate chemical sunscreens as opposed to those with Zinc Oxide, though most articles seem to point us in the direction of Zinc Oxide.
Personally, I'm wondering if this notion isn't simply something that has snowballed from the inertia of some original articles. Certainly the logic is there; Rosaceans often have not only sensitive skin but P&P's which would likey be more easily irritated by chemical sun products.
Here's a list of CDA-Recognized Sunscreens:
I know some have had good luck with La Roche-Posay Anthelios and Ombrelle. Mexoryl isn't available in the USA if I recall (not yet approved by the FDA) but products like the Anthelios can be obtained through mail-order/e-bay. I'm thinking of trying some myself as there is an e-bay seller for it within 1/2hr. drive of me. The chairman of dermatology at Columbia University is quoted as saying it (Mexoryl) gives us almost perfect protection from sunshine.
I don't think zinc oxide products have a lock on skin care for Rosaceans and some people can't use them. The chemical ones above are non-comedogenic while zinc oxide is occlusive.
Apparently just last week, a consumer lawsuit was filed against sunscreen makers accusing them of exposing millions of people to cancer and other dangers. (article wasn't sure if this was lawyer or consumer initiated though)
It's important to keep in mind that sunscreen/block needs to cover the entire UVA/UVB spectrum. Some estimate that UVA is responsible for up to 90% of our skin aging. One site has a picture of a monk who had never been out in daylight and one of an American Indian. Both the same age, I believe. The difference is unreal. Baby skin vs. lines that resemble caverns. UVA can penetrate up to 4 ft. of water. Up to 100% can be reflected off water. 25% off concrete.
Sunscreen is really only intended as a backup to what should be sun avoidance between 10 and 2. A cotton t-shirt will give you an spf of about 5. UVA comes through your windows. (except the front windshield of automobiles due to the laminate/crash protection features)
Sun avoidance should be one's primary consideration. Check your local forcast for the UV index. Consider sunscreen rated clothing.
Some actives are thought to increase the SPF rating of sunscreens, however without the concoction being submitted for testing, you are really rolling the dice. Better to use the actives prior to putting on the sunscreen, allowing to be absorbed fully. This might mean you can't go out for an HOUR prior to putting on the actives, if you want the sunscreen to be fully effective.
Studies have shown that many people apply sunscreen improperly, rendering it 50-75% less effective than its SPF rating. If you've ever had a blotchy sunburn, this could be why.
Lips are often neglected in one's suncare regime. Don't leave them out. Lighter shades of lipstick are virtually ineffective and besides, lipstick typically wears off during the day. This is where zinc oxide, esp. in newer (nano sized) forms might be the better choice.
Lastly, many Rosaceans are on oral antibiotics which can increase photosensitivity.
With Rosacea, it's important to try things (in moderation) and get to know what works (or not) for you.