Never use any so-called "medications" for ich. Never. Most of these are snake oil, and you are likely to cause more stress and lose fish. Heat works. Increase the tank water temp to 30C/86F and keep it there for two weeks. Do a major water change now, to get as much of the "medication" out as you can. Aside from being basically useless, they can combine with heat causing further trouble for the fish.
If for some reason the ich is resilient, you can move on, but in 99% of the time the heat alone is safer and more effective than any treatment. So says Neale Monks, and that is good enough for me. Plus a marine biologist on another forum who said much the same thing, never use some of the toxic preparations. Characins (tetras, pencilfish, hatchetfish) are especially sensitive to any substances in the water, which is why many "remedies" say half-strength for these fish. But heat does not harm any of them. As
@Essjay mentioned, in summer heat waves the tank temp can exceed this easily. Not a problem.