The aim of this study was to evaluate the presence of total and inorganic arsenic in dietary supplements composed of herbal plants and seaweed, and to determine the potential toxicological risk. Total arsenic was determined by dry ashing and hydride generation atomic absorption spectrometry, and inorganic arsenic was determined by acid digestion, solvent extraction, and hydride generation atomic absorption spectrometry. Total and inorganic arsenic in the supplements ranged from 0.07 to 8.31 mg kg−1 dry weight and from 0.14 to 0.28 mg kg−1 dry weight, respectively. Daily intake of total arsenic ranged from 0.05 to 12.46 μg day−1. Inorganic arsenic intake ranged from 0.21 to 0.83 μg day−1, values that are below the Benchmark Dose Lower Confidence Limit recommended by the Word Health Organization. Therefore, there appears to be a low risk of adverse effects resulting from excess inorganic arsenic intake from these supplements. This is the first study conducted in Mexico that investigates total and inorganic arsenic in dietary supplements. Although the results do not suggest toxicological risk, it is nonetheless important considering the toxicity of inorganic arsenic and the increasing number consumer preferences for dietary supplements. Moreover, it is important to improve and ensure the safety of dietary supplements containing inorganic arsenic.