Are Niacinamide and Nicotinamide the Same? Do They Cause Liver or Kidney Disease?
Yes, niacinamide and nicotinamide are the exact same compound—these are simply two different names for the amide form of vitamin B3. 1, 2, 3 They do not typically cause liver or kidney disease at standard supplemental doses, though hepatotoxicity can occur at very high doses (≥500 mg/day), and caution is warranted in patients with pre-existing liver or kidney disease. 4
Nomenclature Clarification
Niacinamide = Nicotinamide: These terms are completely interchangeable and refer to the same chemical compound, which is the amide form of vitamin B3. 1, 3
Different from Niacin: This compound is distinct from nicotinic acid (also called niacin), which is another form of vitamin B3 with different side effect profiles. 2, 3
Key distinction: Unlike niacin/nicotinic acid, nicotinamide does NOT cause flushing, which is a major differentiating feature. 5, 6
Liver Toxicity Risk
The risk of hepatotoxicity exists but is dose-dependent and generally occurs only at high doses:
Abnormal liver function tests have been reported in persons taking daily doses of 500 mg or more of niacinamide, according to FDA labeling. 4
Niacin (the related compound nicotinic acid) can cause hepatotoxicity ranging from mild liver enzyme elevation to acute liver failure, typically at doses around 3 g per day. 6
Use only under physician supervision if you have a history of jaundice, liver disease, or diabetes, per FDA guidance. 4
At standard supplemental doses used in dermatology (typically well below 500 mg/day), nicotinamide has a favorable safety profile and is generally well-tolerated. 5, 2
Kidney Disease Risk
The safety profile in individuals with kidney disease has not been well established:
Populations with kidney disease may be at higher risk for adverse effects due to altered metabolism or excretion. 7
The primary route of excretion is through the urinary tract, with metabolites including N1-methylnicotinamide and N1-methyl-4-pyridone-3-carboxamide. 1
No direct nephrotoxicity has been established in the literature, but caution is advised in renal impairment due to altered clearance. 7
Safety Profile at Standard Doses
Nicotinamide is typically well tolerated with a minimal side-effect profile:
The European Food Safety Authority has established an upper intake level for nicotinamide at 12.5 mg/kg body weight/day or approximately 900 mg/day for adults. 7, 8
No adverse effects were observed at doses up to 25 mg/kg body weight/day in diabetic subjects. 8
Common side effects are primarily gastrointestinal: nausea, vomiting, diarrhea, and anorexia. 7
Allergic sensitization has been reported rarely. 4
Clinical Context and Monitoring
When prescribing nicotinamide, consider the following:
Monitor liver function tests in patients taking doses ≥500 mg/day, particularly those with pre-existing liver disease. 4
Urinary metabolites (N-methyl-nicotinamide and N-methyl-2-pyridone-carboxamide) can be used to assess niacin status and monitor for excessive intake. 7, 8
Exercise caution with medications that interact with the cytochrome P450 enzyme system and diabetes medications due to potential effects on insulin levels. 7
There is insufficient evidence regarding safety during pregnancy and lactation. 7, 4
Practical Dosing Guidance
Standard therapeutic doses are well below the hepatotoxicity threshold:
Recommended daily intake varies by population: adult males 16 mg/day, adult females 14 mg/day, pregnant women 18 mg/day. 8
Clinical dermatologic use typically involves doses that are higher than dietary recommendations but still generally below 500 mg/day. 5, 2
The upper limit for nicotinamide (900 mg/day for adults) provides a substantial safety margin. 8