Primary focal hyperhidrosis (HH) is a chronic disorder of excessive sweating. A single-center, open-label study was performed to determine the efficacy and safety of 15% aluminum chloride (AC) in 2% salicylic acid gel base (SAGB) Hydrosal in adults with moderate-to-severe primary axillary HH. Thirty subjects were given 15% AC in 2% SAGB to apply to their bilateral axillae nightly for the first week, then twice-weekly application as tolerated. The primary objective was change in mean Hyperhidrosis Disease Severity Score (HDSS) score from baseline to week 4. Participants who achieved an HDSS score < 2 were designated as "responders." Mean change in HDSS from baseline to week 4 was 1.32 (p = 0.0001). At week 4, 21 of 29 (72%) were responders, and at week 12, 18 of 25 (72%) were responders. Based on these results, 15% AC in 2% SAGB may be an effective, high-strength AC topical therapy for treatment of patients with moderate-to-severe axillary HH.