Nicotinamide, also known as niacinamide, is a water-soluble amide form of niacin or vitamin B3. It is found in foods such as fish, poultry, eggs, and cereal grains. It is also marketed as a dietary supplement, and as a non-flushing form of niacin.

Nicotinamide has established medical uses to treat conditions stemming from niacin deficiency such as pellagra. Oral and topical formulations are used to treat a variety of inflammatory skin conditions including acne vulgaris and rosacea ^{(1) (24) (2)}, hyperpigmentation ⁽²⁵⁾ and to prevent hair thinning ⁽²⁶⁾.

Preclinical models demonstrate photoimmunoprotective and chemopreventive effects against UV radiation ⁽⁴⁾. Nicotinamide enhances repair of UV radiation-induced DNA damage in human melanocytes ⁽⁵⁾ and keratinocytes ⁽⁶⁾ and similar effects have been demonstrated in human studies ^{(4) (7) (8)}. It was also shown to improve inner retinal ⁽²⁷⁾ and visual function ⁽²⁸⁾ in patients treated for glaucoma. Other clinical trials show oral nicotinamide reduces UV-induced ⁽⁹⁾ and photodynamic therapy (PDT)-induced ⁽¹⁰⁾ immunosuppression.

In patients with sun-damaged skin, oral nicotinamide helped prevent the occurrence of nonaggressive skin cancers ⁽¹¹⁾. In a small trial among renal transplant patients however, similar effects were not significant ⁽¹²⁾. Other studies found a reduction in actinic keratoses, a predictor of melanoma risk ^(13) (21), and a meta-analysis reported association with significant reductions in basal cell and squamous cell carcinomas, but increased risk of digestive adverse events ⁽²⁹⁾. Additional studies are warranted ⁽¹⁴⁾.

Nicotinamide appears to be largely well tolerated in clinical studies ^{(11) (12) (13)}. Even though niacin is converted into nicotinamide in the body ⁽¹⁾, these two supplements should not be viewed as interchangeable as they have different side effect profiles ^(11) (15).