boils

I wonder what kind of boils you are talking about and the age of your friend. One of the causes can be hygiene: so wash prober, keep it clean, only wear cotton clothes and eath healthy. An other reason can be change in hormons: hygeniene is still important (see above) and keeping the hormone balance the same. An other reason can be a result of allergies (food, clothes, stress, lack of sleep, etc). Then you need to find out what causes it. Might be interesting to keep a diary. Write down what you ate, when they pop up, might be you find some scedule and the reason that way.

I would say to keep himself clean as well as the surfaces that touch his skin. As I have occasional issues with this as well. So no wearing clothes more than once, no using bath towels more than once, and watch for boils to show up in places you have shaved as that could cause a hair to be come ingrown and cause an infection/boil.