Patients with rosacea are particularly susceptible to the irritation caused by sunscreen ingredients. The purpose of this bilateral comparison study was to examine the effects of different ingredients found in sunscreen on facial cutaneous irritancy in patients with rosacea. patients clinically diagnosed with rosacea were asked to test different preparations of common sunscreens on their faces. The results show that the presence or absence of appropriate protective ingredients, such as dimethicone and cyclomethicone in the vehicle, may prevent irritation from other sunscreen ingredients in patients with inflammatory conditions such as rosacea.