Drug interactions
Isoniazid + Vitamin b3
Severity: Minor
Isoniazid and Vitamin b3: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoniazid can interfere with niacin status and, in malnourished patients, may precipitate pellagra-like features such as dermatitis, diarrhea, and neurological symptoms. This is more likely with prolonged therapy and poor nutrition.
What this interaction means in plain words
Isoniazid and Vitamin b3 have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Isoniazid belongs to Anti Bacterial; Vitamin b3 belongs to Gastrointestinal Tract.
Why it happens
Isoniazid interferes with pyridoxine-dependent conversion of tryptophan to niacin and may impair nicotinamide metabolism, reducing niacin availability.
What to do
Watch for pellagra signs in malnourished patients on isoniazid and give niacin or nicotinamide supplementation if deficiency is suspected; give pyridoxine routinely as per tuberculosis guidelines.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Vitamin b3
- Lovastatin + Vitamin b3 Major
- Simvastatin + Vitamin b3 Major
- Atorvastatin + Vitamin b3 Moderate
- Cholestyramine + Vitamin b3 Moderate
- Colestipol + Vitamin b3 Moderate
- Fluvastatin + Vitamin b3 Moderate
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Vitamin b3?
MediHelp rates the interaction as minor. Isoniazid and Vitamin b3 have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Isoniazid can interfere with niacin status and, in malnourished patients, may precipitate pellagra-like features such as dermatitis, diarrhea, and neurological symptoms. This is more likely with prolonged therapy and poor nutrition.
How serious is the interaction between Isoniazid and Vitamin b3?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Watch for pellagra signs in malnourished patients on isoniazid and give niacin or nicotinamide supplementation if deficiency is suspected; give pyridoxine routinely as per tuberculosis guidelines.
What other medicines interact with Vitamin b3?
MediHelp also lists interactions of Vitamin b3 with, for example, Lovastatin, Simvastatin, Atorvastatin. The full list is on the Vitamin b3 page.
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