You Should Never Take Vitamin B12 With This Common Antibiotic

Vitamin B12 is important to our health, and antibiotics can be critical for treating infection. If you're not getting enough vitamin B12 through your diet, you may decide to take a supplement (oral or injected) to meet your nutritional needs. But before you do, make sure you're aware of drug interactions — especially with antibiotics.

Vitamin B12, also known as cobalamin, is important for cell formation and metabolism, nerve function, and the creation of DNA, according to the Mayo Clinic. It is present in animal products including beef, poultry, fish, and dairy, but not in plant foods. Sometimes it's added to foods, such as fortified breakfast cereals. Vegans, vegetarians, and people with digestive issues that make it difficult to absorb nutrients may be at risk of vitamin B12 deficiency.

Supplementing your diet with a small dose of vitamin B12 is generally considered safe (via Mayo Clinic). The recommended daily amount is 2.4 micrograms. However, even the recommended dosage can interact with certain drugs that could cause adverse effects.

Taking vitamin B12 while on a dose of the common antibiotic tetracycline — often prescribed to treat bacterial infections such as acne, pneumonia, and Lyme disease (via MedlinePlus) — can interfere with the absorption and effectiveness of the medication, say experts at Mount Sinai. In order to make sure antibiotic therapy is effective, B12 and any other B vitamins should not be taken at the same time of day as the medication. 

Long-term use of any antibiotics, according to MedlinePlus, can interfere with the body's ability to absorb vitamin B levels, particularly vitamins B2, B9, and B12. Mount Sinai medical staff claim other kinds of medications, such as anti-seizure therapies, chemotherapy drugs, Metformin (a diabetes medication), H2 blockers like Pepcid AC and Zantac, and proton pump inhibitors like Prilosec and Nexium, also can deplete the body of B vitamins.

Use caution when taking vitamin B12 with any antibiotics, but especially tetracycline. Tell your doctor about any supplements you're consuming before taking any antibiotic or medications you're not sure about.