Vitamin B12 is an essential vitamin that plays key roles in the formation of red blood cells, neurological function and DNA synthesis. It is obtained from a variety of animal food sources, including red meat, fish, poultry, eggs, milk, and dairy products. Some common medications interact with vitamin B12 or block its absorption in the body. These may cause vitamin B12 depletion in some individuals. Symptoms of vitamin B12 deficiency include anemia, fatigue, weakness, constipation, loss of appetite, weight loss, numbness and tingling in the hands and feet.
Antibiotics
All members of the vitamin B family, including vitamin B12, interfere with the absorption of the antibiotic tetracycline. This problem can be avoided by taking vitamin B12 at a different time of the day from tetracycline. There is also some limited evidence that the antibiotic chloramphenicol may block the red blood cell response to supplemental vitamin B12.
Cholesterol-Lowering Medications
Drugs that sequester bile acids are used to treat high cholesterol levels in the body. According to the University of Maryland Medical Center, medications in this class appear to interfere with vitamin B12. These drugs include colestipol, cholestyramine and colsevelam.
Ulcer Medications
Drugs used to treat peptic ulcer and gastroesophageal reflux disease slow down the release of gastric acid in the the stomach. They may deplete vitamin B12 by inhibiting the body's ability to absorb the vitamin from food. Medications in this class include the H2 blockers, such as cimetidine, famotidine and ranitidine, and the proton pump inhibitors, such as esomeprazole, lansprazole, omeprazole and rabeprazole.
Other Medications
A variety of other medications may interact with vitamin B12 and cause depletion in some individuals. These include the anticonvulsants drugs phenytoin, phenobarbital and primidone. The chemotherapy drug methotrexate interferes with vitamin B12. A number of studies have shown vitamin B12 depletion in diabetic patients treated with metformin. Colchicine, used in the treatment of gout, may also block vitamin B12 absorption in the body.
