Under federal regulations, raw milk, both conventional and organic, is tested for a common family of antibiotics known as beta-lactams. Milk is tested for at least four of six beta-lactam antibiotics, including penicillin and amoxicillin. If there are too many of such medications in the milk, it is rejected. However, most raw milk comes from cows that have not been given these drugs, so they are not present in the milk.