Hi what's the side effect of conatact lens for myopia?ist bad?for how many hours i have to wear them?

Should be none: Contact lenses are a substitute for eyeglass correction. When properly fit and with the proper power, you should see well and there should be no side effects if you keep the schedule prescribed. Always remove the lenses if the eye(s) gets red and replace them according to schedule and there should be no issues. Wear them as long as you need good vision within the proper schedule.