I second aloe vera -- I have extremely sensitive skin that burns exceptionally easy, and have had a number of second-degree sunburns throughout my life. Aloe does an excellent job of cooling the burn, and reduces the appearance of the burn within 24 hours. If I put aloe on directly after any inadvertent excessive sun exposure (i.e. I forgot to re-apply sunscreen on time) then I don't blister either. Get the pure gel, which means avoid most of what is normally offered in grocery stores and the like -- they may add dyes, menthol, alcohol, etc. that can irritate the skin and prolong healing times.