The Physician's Desk Reference (PDR), a book of detailed information about
ion medicines, says Magnesium can reduce the effectiveness of Amoxicillin if taken close together. My son was prescribed Amoxi and Magnesium. (They didn't tell me not to give them to him at the same time, but I read the package inserts and PDR carefully) A Neurologist had me give him 400mg daily which is the adult dose, they said it was ok, even for his appx 60 lb size.
A study released last year said Lyme is dependent an Manganese, which is also too important to go with out. By luck a friend introduced me to hemp seeds which have a huge amount of both Manganese and Magnesium. I posted a bunch about that in the past. The RDA numbers and a company contact, etc is findable using the Google custom search button up top -search for Manganese. Many foods have a ridiculous serving size to get the RDA. With the shelled hemp seeds it was about 2 tablespoons if I remember. One company even sells them covered in chocolate and you knw that's GOT to be good for you!