Vesicants and some nerve agents penetrate exposed skin, mainly through the sensitive integration areas of the personal protective equipment. Therefore, improving dermal barrier with a topical agent should reduce the threat of exposure. A topical skin protectant lotion (IB1) was developed to improve protection against chemical warfare agents. Preclinical studies in several animal models have proven the protective efficacy of IB1. Here we present the results of a randomized placebo-controlled, double-blind phase I clinical study, performed with 34 healthy volunteers. The study tested the safety of repeated applications, including ruling out transdermal permeation of magnesium, which may lead to a dangerous blood magnesium level, since the lotion contains magnesium sulfate. Other objectives included detection of dermatological adverse effects, assessment of application convenience, and effect on daily activities. Importantly, no serious adverse effects were recorded and the lotion did not interfere with daily tasks. There were no significant differences in magnesium levels between the placebo and the study groups in any of the applications. No toxic levels of magnesium were found in either group. We conclude that IB1 is probably safe, easily self-applied, and does not cause any significant inconvenience. Therefore, IB1 can be considered as an adjunctive chemical, biological, and radio-nuclear (CBRN) protective aid to field soldiers.