Pellagra (vitamin B3 deficiency)
Severe niacin and tryptophan deficiency. Classic three Ds: dermatitis on sun-exposed areas, diarrhoea, dementia. Seen in malnutrition, alcoholism, Hartnup disease and long-term isoniazid therapy without pyridoxine.
ICD-10 E522 drugs
Also known as: Niacin deficiency, 3-D disease
Drugs used for this condition
- ANicotinamideFirst line · Water-soluble vitamin B3 (amide form)Nicotinamide is the treatment of choice for pellagra because it does not cause flushing and is well tolerated at high doses. WHO recommends 100–300 mg/day orally in 3–4 divided doses for 3–4 weeks. Dermatitis and diarrhoea regress in the first days; neurological symptoms in 1–2 weeks. Other B vitamins are replenished and adequate protein intake is ensured in parallel.
- ANicotinic acid (niacin)First line · Lipid-modifying agent, nicotinic acid derivative; vitamin B3 in acid formNicotinic acid is the treatment of choice for confirmed pellagra. WHO recommends nicotinamide 100–300 mg/day orally in 3–4 divided doses for 3–4 weeks, then physiological maintenance. Pellagra is treated with nicotinamide rather than nicotinic acid to avoid flushing in severely ill patients. Other B vitamins are replenished in parallel (deficiency is often combined) and adequate protein intake is ensured to restore tryptophan synthesis.
How to read tiers A–F
Evidence tiers belong to the drug-indication pair, not to the drug as a whole: the same substance can be A for one condition and F for another.
- AStrong evidence – first or second line in international guidelines
- BRecommended in selected cases
- CStudy data contradict each other
- DBenefit not proven, no documented harm
- FDocumented harm, or risk without benefit