What's his diet like? Does he eat a lot of refined sugar and/or dairy? They are both known to increase acne in certain people. It's worth investigating, but it is a big adjustment & isn't always a cure. I tried cutting them out & it didn't work, but some people swear by it. You have to be absolutely rigorous if you're going to try eliminating dairy as a possible cause.
I've had roaccutane (big improvement, extremely drying, lots of side effects), epiduo (cream, easy for the face, somewhat problematic to apply it to your own back) & differin (basically a milder version of epiduo). Both somewhat helpful.
Steer clear of products that strip all moisture from the skin, any one-step "cleansers" containing alcohol, physical exfoliants. They irritate the skin, often causing it to produce more oil to protect itself. Gentle is key.
If he wears pyjamas to bed, ideally he needs clean ones at least every 2nd night. Every night would be better. A pack of cheap cotton t-shirts to change every night will suffice. Ditto, pillowcases. Dirty fabric against the skin will harbour bacteria. Ditto, towels - he should have his own towels, ideally changed every couple of days. Get him a pack of 4 or so & wash them weekly.
For individual blemishes, honestly the best thing I've found is plain old tea tree oil, applied neat. It smells quite medicinal but not too bad & it's not visible.