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Niacinamide Side Effects

For the Consumer

Applies to niacinamide: tablets

Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Diarrhea; dizziness; headache; itching; nausea; stomach upset; temporary feeling of warmth or flushing of the skin.

Seek medical attention right away if any of these SEVERE side effects occur while taking niacinamide:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); black, tarry, or bloody stools; changes in vision; dark urine; decreased urination; fast or irregular heartbeat; loss of appetite; muscle pain or weakness; numbness or persistent tingling of the skin; persistent nausea, vomiting, or general "unwell" feeling; severe or prolonged flushing of the skin; stomach pain; swelling of the hands, legs, or feet; vomit that looks like coffee grounds; yellowing of the skin or eyes.

For Healthcare Professionals

Applies to niacinamide: compounding powder, oral tablet


Cardiovascular side effects are rare and mild and have included tachycardia.[Ref]


Metabolic side effects have included hyperglycemia and hyperuricemia.[Ref]

Nervous system

Nervous system side effects have included headache.[Ref]


Gastrointestinal side effects have included bloating, flatulence, diarrhea, stomach upset, and nausea.[Ref]


Dermatologic side effects have included increased sebaceous gland activity, dry skin, itching, and rash.[Ref]


1. Baumgartner TG, ed. "Clinical Guide to Parenteral Micronutrition." Gainsville, FL: Fujisawa (1991):

2. Sugar AM, Liu XP "Efficacy of voriconazole in treatment of murine pulmonary blastomycosis." Antimicrob Agents Chemother 45 (2001): 601-4

It is possible that some side effects of niacinamide may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

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