If you got off with only a "red patch'" you got off lightly. I spilled some on myself many years ago. It ran through my overall, down my ribs and into the top of my trousers. It evaporated very quickly. No problem. I had spilt it on me before with no side effects.
About twenty minutes later, in flight, I felt a burning sensation begin under my belt. I wasn't on fire but it soon began to feel like it. The pain became excruciating.
Luckily I was in a situation where I could land and quickly investigate. The skin on my hip, where the belt had prevented evaporation, was red and then turned black - the same black that you get if you spilled silver nitrate (IIRC) on your skin in chemistry class. It tooks a month or two to recover. I was more careful after that little incident.