Unless it is proved with tests that he has a specific immune disorder, no immune medicines will actually give him better power to face infections. There are several herbal and food-based products in the market, and even homeopathic drops ... but these are not going to help. All they do is give you a false sense of satisfaction that you are giving something ... and most such products are very, very expensive. So they do improve the bottom line of the manufacturing companies, but little else.