Hi Fran - For the milk thistle, I suggest he start with a small dose. Milk thistle usually causes the liver to start releasing old toxins, and this causes cleansing reactions. If he has no reactions, or if they are mild, he can experiment with gradually increasing the dose. If he starts experiencing major cleansing reactions, he should reduce his dosage until they subside. Eventually, he should find a dosage that works and produces no or mild reactions.