Fasting is all about self restraint if you eat or drink my mistake then you just keep the fast.if you're on medication and it's important that you don't miss it you don't have to fast you just feed the poor but just say you get better after a few month or stop the medication then you make up for the fasts you miss. Like my grandma is over 70 and diabetic so she can't fast all she does is feed a poor person for 30 days.