In my experience, it's a complete waste of time to medicate for ich. All you have to do is crank up the heat. Once I was lucky enough to get ich in two 10 gallons that I have in the same stand (odd ... never thought I'd say it was lucky). Anyway, the untimely outbreak in two *very* similar aquariums afforded me the opportunity to conduct a test. Both aquariums had the exact same water stats, and were even stocked with similar tetras (pristella in one, red phantom in the other.)
In one aquarium I simply cranked up the temp to 88 degrees. In the other aquarium I used medication (can't remember the brand). Both aquariums cleared up with only 1 fish lost each. However, the medicated one took about 3 extra days, plus water changes, plus discoloration from the medicaton.
If you have an outbreak of ich, I highly recommend simply using heat to correct the situation.