Table 1.

Acute and Chronic Toxicities Due to Skin, Hair, and Nail Supplements (Selected Examples)

Acute Toxicity	Ingredient
Dysphagia or choking, particularly among adults ≥ 65 [10]	Tablet size >22 mm
Sedation and falling risk [12]	Melatonin
Calcium oxalate kidney stones [13,14] Acute hemolysis in patients with G6PD deficiency [15]	High-dose vitamin C
Rosacea fulminans [16]	High-dose vitamin B6 High-dose vitamin B12
Chronic Toxicity
Constipation, gastrointestinal upset, reduced zinc uptake [18,19]	High-dose iron
Increased all-cause mortality [21] Increased incidence of type 2 diabetes, dyslipidemia, and hyperglycemia [22–25]	High-dose selenium