This study evaluated the efficacy and tolerability of topical aluminum sesquichlorohydrate (AS) when compared to aluminum chloride (AC) as a treatment for primary axillary hyperhidrosis (PAH). Twenty subjects were included in this randomized, controlled, split-side 8-week study. All participants applied 20% AS and 20% AC lotions in their axillae (one treatment per axilla) every night for 2 weeks; next, the application was reduced to three times a week for 4 weeks. The assessment was performed using the sweating intensity visual scale (SIVS), hyperhidrosis disease severity score (HDSS), patient satisfaction score, and the appearance of adverse effects on weeks 0, 1, 2, 4, 6, and 8. Both AS as well as AC application showed positive results, significantly differing from the baseline, as assessed using SIVS, HDSS, and patient satisfaction score at every follow-up visit; however, no significant difference was observed between the AS and AC groups at any follow-up visit. The mean time of response was 1.14 weeks for both treatments. A side effect was observed in one subject (5%), who reported itching on the AC axilla. The therapeutic effects persisted even after reducing the frequency of application and lasted for at least 2 weeks after cessation of use. In conclusion, topical 20% AS demonstrated similar efficacy to topical 20% AC in the treatment of PAH, with a high safety profile.