What is the recommended dose of niacin (Vitamin B3) for treating pellagra?

Niacin Dosing for Pellagra Treatment

For acute pellagra treatment, administer nicotinamide 100 mg three times daily (300 mg total daily dose) for 3 weeks, with a maximum total daily dose not exceeding 600 mg. 1

Treatment Regimen

Standard Dosing Protocol

• Nicotinamide (preferred form): 100 mg orally three times daily for 3 weeks 1
• Alternative dosing: Nicotinic acid 15-20 mg/day OR nicotinamide 300 mg/day are effective for treating traditional pellagra at physiological amounts 1
• Maximum daily dose: Do not exceed 600 mg total daily dose of nicotinamide 1

Route of Administration

• Use oral/enteral route whenever the gastrointestinal tract is functional 1
• In cases of malabsorption or short bowel syndrome, the parenteral route can be used 1

Clinical Context and Monitoring

Expected Response Timeline

• Cutaneous symptoms should resolve within 24-48 hours after oral niacin administration, which can help confirm the diagnosis 2
• Continue treatment for the full 3-week course even after symptom improvement 1

Comprehensive Nutritional Support

• Add other B vitamins, zinc, and magnesium to the treatment regimen, as pellagra rarely occurs in isolation 3
• Provide a diet rich in calories and niacin-containing foods (eggs, bran, peanuts, meat, poultry, fish, legumes) 3
• Consider vitamin B complex tablets for prevention when dietary niacin is deficient 1

Important Safety Considerations

Toxicity Thresholds

• Flushing can occur at doses as low as 30 mg 1
• Hepatotoxicity risk increases significantly around 3 g per day (3000 mg), far above therapeutic pellagra doses 1
• The recommended pellagra treatment doses (300-600 mg/day) are well below toxicity thresholds 1

High-Risk Populations Requiring Treatment

• Chronic alcoholics with malabsorption 1, 3
• Patients with anorexia nervosa showing sun-exposed erythema, glossitis, or stomatitis 2
• Maize-eating populations without niacin fortification 1
• Patients on medications that interfere with niacin metabolism (isoniazid, 5-fluorouracil, anticonvulsants) 3
• Cancer patients undergoing DNA-damaging treatments (radiation, chemotherapy) 1

Diagnostic Confirmation

Clinical Recognition

• Look for the classic "3D syndrome": dermatitis (bilaterally symmetrical on sun-exposed areas), diarrhea (watery, occasionally bloody), and dementia (confusion, memory loss, psychosis) 3, 4
• Early nonspecific symptoms include photophobia, asthenia, depression, anorexia, and epigastric discomfort 3

Laboratory Testing (Optional)

• Low urinary excretion of N-methylnicotinamide and pyridone indicates niacin deficiency 3
• Blood or tissue NAD levels may be measured, though storing a blood sample and awaiting response to niacin supplementation is a pragmatic alternative 1

Critical Pitfall to Avoid

Do not delay treatment while awaiting laboratory confirmation if clinical suspicion is high based on the 3D presentation and risk factors—pellagra progresses to death if untreated, but responds dramatically to niacin within 24-48 hours 2, 4. The therapeutic trial itself serves as a diagnostic test.