Deodorant vs. Antiperspirant, and What "Aluminum-Free" Actually Means

What the rule calls an antiperspirant

The federal rule is 21 CFR Part 350, titled “Antiperspirant Drug Products for Over-the-Counter Human Use.” Its definition is one sentence. An antiperspirant is “a drug product applied topically that reduces the production of perspiration (sweat) at that site.” A product that meets every condition in the rule is “generally recognized as safe and effective and is not misbranded,” which is what lets it be sold without its own FDA approval.

The rule then lists the only active ingredients such a product may use. There are eighteen, and every one is an aluminum compound. Aluminum chloride is allowed up to 15 percent in a water-based, nonaerosol form. Aluminum chlorohydrate and eight related aluminum compounds are allowed up to 25 percent, in aerosol or nonaerosol form. Eight aluminum zirconium compounds are allowed up to 20 percent, in nonaerosol form only. Nothing else is on the list.

Where a deodorant falls

The rule covers one claim, reducing sweat. A product that promises only to control odor makes no such claim, so Part 350 has nothing to say about it. The line comes from the Federal Food, Drug, and Cosmetic Act itself. It defines a drug to include “articles (other than food) intended to affect the structure or any function of the body,” and a cosmetic as articles applied to the body “for cleansing, beautifying, promoting attractiveness, or altering the appearance.” Reducing how much you sweat is a claim about a function of the body. Smelling better is not. Read against those two definitions, a product that claims less sweat is on the drug side, and one that claims only odor control is on the cosmetic side.

One product can carry both words. A stick labeled “antiperspirant deodorant” is an antiperspirant under Part 350, because the rule requires the labeling to identify the product as an “antiperspirant” and that is the claim it makes. Whatever else the front of the package says, the statement of identity and the active ingredient are what tell you which category you’re holding.

What the label is allowed to say

Part 350 doesn’t just permit the sweat claim. It dictates the wording. Under “Uses,” every antiperspirant must state that it “decreases,” “lessens,” or “reduces” underarm “dampness,” “perspiration,” “sweat,” “sweating,” or “wetness.” The manufacturer picks one word from each list. It may add that the product also reduces underarm wetness “due to stress.”

Duration claims are earned, not asserted. “All day protection,” “lasts all day,” “lasts 24 hours,” or “24 hour protection” is allowed for a product that demonstrates a 20 percent reduction in sweat over a 24-hour period. “Extra effective” requires a 30 percent reduction. A product that demonstrates the 30 percent reduction sustained over 24 hours may combine the two, as in “24 hour extra effective protection.” FDA keeps guidelines on file for how that effectiveness testing is done. So the strongest claim the rule allows is a reduction, never elimination.

The warnings every antiperspirant carries

The rule also fixes what goes under “Warnings.” Every over-the-counter antiperspirant must say “do not use on broken skin,” “stop use if rash or irritation occurs,” and “ask a doctor before use if you have kidney disease.” An aerosol adds “keep away from face and mouth to avoid breathing it.” Under “Directions,” the required statement is “apply to underarms only.”

Those are the rule’s words, printed because the rule requires them. This post reports the requirement and stops there. Part 350 doesn’t explain the reasoning behind any of its warnings, and we don’t fill that in.

What “aluminum-free” tells you, and what it doesn’t

It tells you the product is a deodorant under this rule. It contains none of the eighteen permitted actives, so it makes no antiperspirant claim, and it can’t promise less sweat. What it promises instead is odor control, which the rule doesn’t regulate.

You can confirm that on the shelf without reading marketing copy. An antiperspirant identifies itself as one and names an active ingredient from the list above. A deodorant has neither.

The label doesn’t tell you about fragrance, which is a separate question with its own vocabulary. See Fragrance-Free vs. Unscented, and Why the Difference Matters for what those two words actually mean. And it says nothing about how the odor-control ingredients suit any particular skin, which is outside what this rule addresses and outside what this post claims.

Where this comes from

Every statement about what an antiperspirant is, may claim, and must warn is quoted or paraphrased from 21 CFR Part 350 as published on eCFR, linked above. The drug and cosmetic definitions are quoted from 21 U.S.C. 321, linked above. Runlow has not tested any deodorant or antiperspirant, and this post makes no claim about any product or ingredient beyond what the rule and the statute state.

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