Does ipill work if taken 4 days after periods?

Depending on how long your cycle is, you were probably already in your fertile window, unless you have a very long menstrual cycle.

With a 28 day menstrual cycle, for example, you would already be in your fertile window.

Most women with a 28 day cycle ovulate on or close to day 14, & you are fertile for up to 6 days before ovulation.

So, it depends how long your cycle usually is.

ipill is not guaranteed to work at any time. It's just worth a try in an emergency.

The only emergency pill shown can work within the 24 hours around ovulation, itself, is, Ella (Ulipristal Acetate), but even that is not guaranteed. ipill might work, at that time, but it has never been proven.

It doesn't sound like you were in the 24 hours around ovulation, so hopefully you will not become pregnant, after using ipill. Hopefully it has time to delay your ovulation, & prevent that happening.