When my son was 8 weeks old I had pneumonia that was not responding to anything. As a last resort my doctor (a LLL medical associate) put me on tetracycline. He saaid that when you take tetracycline and drink milk it negates the effest of the drug, and the same is true of the amount of tetracycline in breastmilk the milk negates the effects on the baby. I don't have Dr Hale's book so can't document this. I can say that my son is now 9 years old and very large and healthy. Nancy Sherwood LLLL, IBCLC- Perth, Australia