SFP 50 has been reported to be unsuitable for sensitive skin. I have never had a bad reaction but since changing my face sun cream to SFP20 or 30 I have seen so much improvement in my skin.
I tried Avene Hydrance Optimale UV Rich SFP 20 price at time of purchase £14.99 at http://Lookfantastic.comThis price does vary depending on where you purchase this product.
I have been using Avene Hydrance Optimale UV Rich SFP 20 over a serum in England and on holiday in Spain it is very effective. I have worn it all year round, no burning from the sun or wind. I have tanned better and this product has protected my skin so that I have seen a significant reduction in redness around my cheek area. For those of you experiencing sensitive skin I would highly recommend a change in you sunscreen.