Last year I got a dose of something - poison ivy/oak/sumac, one of those - anyway, bad. I'm used to chigger bites and such and usually just tough it out, but this was extra nasty. I woke up in the middle of the night ready to tear my skin off, and the kind of stuff that was handy (alcohol, calamine lotion, etc.) didn't even give momentary relief. So out of sheer desperation I grabbed a bottle of generic kitchen/bathroom cleaner - the kind with bleach in it (at this point I was ready to use a flame thrower if necessary) - sprayed some of that on and rubbed it in.... and slept like a baby for the rest of the night. I repeated this roughly once a day for the duration of the outbreak with minimal symptoms.
Ok, this is just my little story, I'm NOT recommending this as a remedy, but if you are unable or unwilling (read: too cheap) to go to the drugstore for the ~$30 stuff, well... YMMV.