This is happening to me right now, what really flipped me out is that I was just cooking with flour and thought it was that...but it wouldn't wash off.
After I saw it was spreading really fast I jumped on here and after realising that it was a chemical thing. I remembered I had also cleaned my hot tub with some chemicals and they would of easily spilt on my fingers.
I just hope this stuff goes away, it's really gross.
I found a cure!
I live in Australia, and here we have a soap called "solvol"
It's made from a tough grit and it's basically like a stone, it's made for working men with really rough hands that get beaten up during the day.
Anyway, it works!
The rash went away in less than 15 minutes.
That just happened to me today! My sister and I made sandwiches and suddenly both our hands broke out with white paint splotches that burned and felt like they were putting out heat. We tried washing them, scrapping at the skin- nothing worked. Then we realized the more we touched the bread, the more it burned. We didn't touch any chemicals, glues or anything unusual, just the bread. Started looking up allergic reactions to bleached flour (this type of bread had it sprinkled even on the outside of the crust) and we saw a lot of posts like this. It went away after about an hour or two, but it was really freaky! My husband didn't touch the bread or eat it and he didn't have any reaction. Never had allergies like this before, but I won't be buying bread with bleaches if I can avoid it. Yikes.
UPDATE: IT WASN'T THE BLEACH. PEROXIDE GOT SPILLED AND GOT ON THE CONDIMENT PACKAGING.
I had this exact thing happen to me this morning.
I use a contact soaking solution made of hydrogen peroxide. The contact case leaked into my bathroom drawer yesterday. I thought I had cleaned it all up, but this morning, I grabbed my hairbrush and noticed the handle was damp. I wiped out the drawer. A few minutes later, I noticed this on my hands. It's never happened with my contact solution before, but because some of the liquid sat out overnight where the water could evaporate and leave concentrated solution behind...
Just confirming: yes, it is hydrogen peroxide.
It happened to me from time to time and always on my hands. It is spreading quickly and is burning. At first I thought a spider has bitten me, so I rushed to put on Antisan (an ointment with anti-histamine to put on insect bites for immediate relieve). The anti-histamine ointment immediately took away the stinging/burning and it did not spread further, but the white spots remains until it slowly fades away over about an hour. It would be nice to get a medical doctor's opinion on this. I wash my hands a lot and especially thoroughly before cleaning and handling my contact lenses, so I thought it could be the type of liquid soap I uses, but even on a new type of soap, the condition re-occurs.