4 Findings About Zinc Oxide for Underarm Odor

The tested product was a 1.1% emulsion

Thirty healthy adults aged 21–39 entered the 2020 split-underarm trial¹; 29 completed 13 days. Researchers compared a 1.1% emulsion with vehicle. Colgate-Palmolive supplied formulations and some funding.¹

Eleven people preferred the zinc-treated side

Only 13 participants noticed an odor difference; 11 preferred the zinc-treated side. These were self-ratings, rather than a trained panel’s assessment. 11 of 13 is not a success rate for all 29 completers.¹

Odor improved while pH rose

Skin pH rose about 0.5 versus vehicle, while odor ratings and bacterial counts favored zinc oxide. The findings do not support an acidifying explanation.¹

A diaper-rash paste has a different label and formulation

For comparison, the U.S. Drug Facts for DESITIN Maximum Strength list 40% zinc oxide as a skin protectant for diaper rash. Its ingredients include petrolatum, lanolin, cod liver oil and fragrance; the label also warns that it may stain clothing.²

The trial did not test whether a higher concentration gives greater odor control.¹²

Bring the exact tube to a pharmacist or dermatologist and ask whether its intended use matches your problem.

Decide whether the problem is smell or wetness

The American Academy of Dermatology³ distinguishes deodorants from antiperspirants: odor control does not necessarily reduce sweat production. Its guidance identifies aluminum-containing antiperspirants as sweat-reducing products and recommends dermatology assessment for troublesome sweating or unusual odor.³

If your shirt is still wet after odor improves, record those as separate outcomes. Avoid adding several products together before you know which one changes the problem you are trying to address.

The “Two Jobs, Two Tools” section of Arms Up separates odor from wetness and uses the Fresh Log to follow one product change at a time. Our deodorant-versus-antiperspirant guide explains the label distinction.