Pyridoxine is used to prevent or treat low levels of vitamin B6 in people who do not get enough of the vitamin from their diets. Most people who eat a normal diet do not need extra vitamin B6. However, some conditions (such as liver disease, overactive thyroid, heart failure) or medications (such as isoniazid, cycloserine, hydralazine, penicillamine) can cause low levels of vitamin B6. Vitamin B6 plays an important role in the body. It is needed to maintain the health of nerves, skin, and red blood cells.