Most ich medicatons are copper-based, and copper in such doses can affect fish and plants to varying degrees. Salt is just as bad, worse in my personal view, for sensitive fish like characins, rasbora, catfish, loaches, etc. There is a 100% natural remedy on the market that I have not tried, I think Kordon make it, I've seen it in magazines like TFH.
I tend to let the fish cure themselves if the ich is only a spot or two (or none--fish flashing is usually the preliminary stages when it attacks the gills) on one or two fish. If the infestation is heavy, I have had success with Aquari-Sol and more recently even better with CopperSafe. Raising the temperature to 85F at the same time seemed to work better. Provided the fish can withstand elevated temperatures, raising it to 90F is said to cure ich on its own with no meds. I've not tried this; I have fish for which such high temps would be stressful in itself.