Ipill work with isotroin? Side effects?

My friend had unprotected sex on 3rd September evening and took an ipill the same night. On 4th September evening, while having sex with her boyfriend, he first went inside without a condom and after sometime, wore one and then ejaculated with the condom on. Should she take another ipill? Her menstrual cycle is regular, of 30 days, and last she got her periods was on 14th August. However, she started with isotretinoin course from 27th August (after having isotretinoin for five months and taking a break of one month she started isotretinoin again on 27th August ). Will that have any side effects when taken with ipill? Is ipill effective in this situation? Also, if ipill is taken twice within a week, what can be the expected side effects? Please suggest