my friend is wondering how can he last longer having sex

This shouldn't be in food allergies, but that's okay and maybe you could try stopping just before he is about to ejaculate and then carry on?
Works for my bf.

Anyway also he could try Viagra, which will give his an erection for a lot longer than 2 minutes i should imagine! If he is still concerned tell him to visit a doctor and they will refer him to someone who is a professional with these issues.

Hello there,

Well there are certain techniques which can help your friend to last longer when it comes to sexual intercourse. First of all he needs to wear a condom. This is the best way of protection, from unwanted pregnancy to the sexually transmitted diseases and he will be less sensitive as well.

The second thing he can do is to stop before he ejaculates. This is most common way of practice. During the sexual intercourse when he feels like he is going to cum he needs to stop, calm down and then he can continue.

He can also masturbate during the day, before his girlfriend comes and this should help him to last longer. I hope he will improve his personal record.