It is not recommended to drink milk while taking certain antibiotics, according to Dr. Richard Liebowitz for Everyday Health. This is because the calcium in milk binds with the antibiotic and prevents it from being properly absorbed.
For an antibiotic to work, it must be absorbed by the digestive system, explains Dr. Liebowitz. The antibiotic is then absorbed into the bloodstream where the blood delivers it to the site of infection. Calcium prevents the antibiotic from being absorbed by the digestive system; however, this interference is only for the class of antibiotics known as tetracyclines. Other types of antibiotics may have other restrictions, making it important to always follow the instructions on the prescription bottle.