If you are currently being treated with any of the following medications, you should not use folic acid supplements without first talking to your health care provider.

Antibiotics, Tetracycline -- Folic acid should not be taken at the same time as the antibiotic tetracycline because it interferes with the absorption and effectiveness of this medication. Folic acid either alone or in combination with other B vitamins should be taken at different times from tetracycline. (All vitamin B complex supplements act in this way and should therefore be taken at different times from tetracycline.)

Drugs That Lower Levels of Folic Acid -- These drugs may interfere with the body's absorption of folate, and may mean you need to take a folic acid supplement. Talk to your doctor first.

• Antacids, H2 blockers, proton pump inhibitors
• Bile acid sequestrants
• Carbamazepine
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Sulfasalazine
• Triamterene

When taken for long periods of time, these medications, as well as other anti-inflammatory medicines, can increase the body's need for folic acid.

Birth Control Medications, Anticonvulsants, and Cholesterol-lowering Medications -- Birth control medications, anticonvulsants for seizures (namely, phenytoin and carbamazapine), and cholesterol-lowering medications (namely, bile acid sequestrants, including cholestyramine, colestipol, and colesevelam) may reduce the levels of folic acid in the blood as well as the body's ability to use this vitamin. Extra folate when taking any of these medications may be recommended by your health care provider. When taking bile acid sequestrants for cholesterol, you should take folate at a different time of day.

Methotrexate -- Methotrexate, a medication used to treat cancer, rheumatoid arthritis (RA), and psoriasis, reduces the amount of folic acid in the body. People who take methotrexate for RA or psoriasis may be prescribed higher doses of folic acid, which helps reduce the side effects of methotrexate. People taking methotrexate for cancer, however, should avoid folic acid supplements unless directed by their doctor, because folic acid may interfere with methotrexate's effects on cancer.