Calcium dietary supplements can interact or interfere with certain medicines that you take, and some medicines can lower or raise calcium levels in the body. Here are some examples:
Calcium can reduce the absorption of these drugs when taken together: 
Bisphosphonates (to treat osteoporosis) 
Antibiotics of the fluoroquinolone and tetracycline families 
Levothyroxine (to treat low thyroid activity) 
Phenytoin (an anticonvulsant) 
Tiludronate disodium (to treat Paget’s disease). 
Diuretics differ in their effects. Thiazide-type diuretics (such as Diuril® and Lozol®) reduce calcium excretion by the kidneys which in turn can raise blood calcium levels too high. But loop diuretics (such as Lasix® and Bumex®) increase calcium excretion and thereby lower blood calcium levels. 
Antacids containing aluminum or magnesium increase calcium loss in the urine. 
Mineral oil and stimulant laxatives reduce calcium absorption. 
Glucocorticoids (such as prednisone) can cause calcium depletion and eventually osteoporosis when people use them for months at a time. 
Tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.

Attending physician
Linna Attending physician
Dr. Linna,a Tongji University and several III grade hospitals trained specialist, received her medical degree in 2001, and has18 years of clinical experience. DrLinna is proficient in the diagnosis and treatment of commonly occurring Orthopedics and surgical diseases, such as sports injuries or trauma to the back, neck, shoulder, knee, ankle, and other joints, as well as surgical Congenital disease management. Dr. Linna’s specialist expertise includes minimally invasive surgery, Mainipulation replacement for Fracture or Dislocatio and combined with new diagnostic techniques in treating pediatric surgical diseases.