I use them both together with no issues. They are two completely different products. Shield absorbs certain toxins...Prime removes chlorine, chloramine, ammonia and detoxifies nitrite and nitrate. These are the ingredients in Shield...I don't see anything that would conflict but I'm not a chemist
Composition: Beneficial microbes, beta-glucan, vitamin b group and mineral, amino acids, carotenoid, enzyme, Ginseng/PSB extract, Ginger, colostrum, Mannan Oligosaccharides