i can relate as i had this a few years back think iv grown out of it now though. mine wasn't constantly yellow just when i was tired or when my migraines were playing up. i went to the doctor who said that its called 'gilberts syndrome' but is completly harmless and theres nothing that can be done to prevent it. maybe get it check just in case but from my experince its nothing that will risk your friends health and they will just have to get on with it.