I am sorry your son is having those issues. Unfortunately lactose intolerance is quite common. In my clinical experience lactase enzyme tabs leave a lot to be desired. I have only very few patients who find them helpful enough to allow them to continue to consume dairy products. For the majority of patients the tablets are not enough and while it may reduce the symptoms a bit they are still symptomatic at the end. They are certainly safe so feel free to try them with your son. However, the best outcome will be guaranteed by avoidance of dairy products. Good non cow's milk alternatives include coconut, pea protein (Ripple )milk, hemp milk. If your son does not have tree nut allergies then cashew and almond are also options. Lactaid milk is not tolerated by most patients. For some patients goat or sheep's milk are also acceptable - they are a bit easier to digest than cow's milk but again you will have to try them with your son to see how he responds.
Good luck - I hope he finds an alternative he likes and tolerates.
Monika Korff, MD