What is isoniazid? How does it interact with other drugs?

Vitamin B6

Effect: Supplementation Likely Helpful

Persons who take isoniazid may develop nerve problems such as tingling or
numbness in the arms, hands, legs, and feet. The cause is believed to be the
drug’s interference with the action of vitamin B6
. The use of
isoniazid is one cause of the few occasions in which vitamin B6
deficiency is seen in the developed world.

To prevent these complications, one should take vitamin B6 supplements at a dose of 15 to 30 milligrams per day when using isoniazid.

Vitamin B3

Effect: Supplementation Possibly Helpful

According to animal studies, isoniazid can interfere with the body’s ability to
produce vitamin
B3
(niacin) by blocking a key enzyme. This
can produce either a subtle or an all-out niacin deficiency (known as
pellagra). Taking niacin supplements at standard
U.S. Dietary
Reference Intake (formerly known as the Recommended Dietary
Allowance) doses should help a person get needed niacin.

Vitamin D

Effect: Supplementation Possibly Helpful

Isoniazid may interfere with the body’s ability to use vitamin D.
Although it is not clear whether this actually causes symptoms of vitamin D
deficiency, it still might be a good idea to take vitamin D
supplements at standard U.S. Adequate Intake (AI) dosages.

Bibliography

Ishii, N., and Y. Nishihara. “Pellagra Encephalopathy Among Tuberculous Patients: Its Relation to Isoniazid Therapy.” Journal of Neurology, Neurosurgery, and Psychiatry 48 (1985): 628-634.

Mandell, G. L., and W. A. Petri. “Antimicrobial Agents: Drugs Used in the Chemotherapy of Tuberculosis, Mycobacterium avium Complex Disease, and Leprosy.” In Goodman and Gilman’s The Pharmacological Basis of Therapeutics, edited by Laurence L. Brunton et al. 11th ed. New York: McGraw-Hill Medical, 2011.