TL;DR
The line between a cosmetic and an over-the-counter drug in US skincare is drawn by the claim, not the ingredient. A moisturizer that says “softens skin” is a cosmetic. The same moisturizer with the same formula, if it says “treats eczema,” is an OTC drug and requires monograph compliance. This is why every retinol serum says “appearance of wrinkles” rather than “treats wrinkles.”
The single weirdest feature of US skincare regulation is that the same physical product can be a cosmetic or a drug depending on what the label says. A cream is not classified by what it is; it is classified by what the brand claims it does. Move the marketing language an inch in either direction and the regulatory regime changes entirely.
What it actually is
The Federal Food, Drug, and Cosmetic Act defines a cosmetic as a product intended to cleanse, beautify, promote attractiveness, or alter appearance, without affecting the structure or function of the body. A drug is any product intended to diagnose, cure, mitigate, treat, or prevent disease, or to affect the structure or function of the body.
The key phrase is “intended to.” Intent is established by the claims a brand makes on the label, in advertising, and in marketing materials. A product with no claims at all defaults to its most likely use; a product with explicit claims is classified by those claims.
Several common skincare ingredients have a regulatory dual identity. Salicylic acid at 0.5 to 2 percent is an OTC acne drug when claimed as acne treatment; the same molecule at the same concentration is a cosmetic exfoliant when the claim is “smoother skin.” Hydroquinone, until recently widely used for skin lightening, is now restricted as a drug ingredient. Retinol is cosmetic; tretinoin (its acid form) is a prescription drug.
Sunscreen sits in its own category. In the US, sunscreens are OTC drugs regulated under a specific monograph. The active ingredients (avobenzone, zinc oxide, titanium dioxide, etc.) and their permitted concentrations are pre-approved; finished sunscreen products must comply with monograph requirements including SPF testing.
Why it matters
The legal classification determines what testing is required, what claims are permitted, and what enforcement applies. OTC drug ingredients must comply with a published monograph (specific approved actives at specific concentrations) or have specific FDA approval. Cosmetic ingredients have no such pre-approval requirement (except for color additives).
The practical consequence is that brands are highly motivated to position products as cosmetics whenever possible. Cosmetic claims are faster to launch, cheaper to substantiate, and less regulated. The minute a brand claims a product “treats” a condition, the regulatory burden multiplies.
This is the reason cosmetic copy reads the way it does. “Reduces the appearance of fine lines” rather than “reduces fine lines.” “Helps clarify the complexion” rather than “treats acne.” “Supports skin barrier function” rather than “heals damaged skin.” The hedged language is engineered to stay on the cosmetic side of the line.
What you can do
Read claim language as a regulatory signal. Hedged language (“appearance of,” “supports,” “helps”) indicates cosmetic positioning. Direct language (“treats,” “cures,” “prevents disease”) indicates drug positioning or aspirational marketing that may be over the line.
For products that should be drugs but are marketed as cosmetics, the FDA periodically issues warning letters. The 2022 warning letters to certain skin-lightening products are a recent example: brands claiming to “treat melasma” with hydroquinone-containing products were forced to either drop the claim or comply with drug regulation.
For products that genuinely belong on the drug side (acne treatments, sunscreens, dandruff shampoos, antiperspirants), the OTC monograph compliance is what you want. Look for “Drug Facts” panels on the label, which is the OTC drug labeling format. Cosmetic-only products do not have Drug Facts panels.
For ingredient curiosity, the FDA’s OTC drug monograph page lists which actives are approved for which OTC categories. The monograph is the authoritative reference for what concentration of salicylic acid counts as an acne drug versus a cosmetic exfoliant.
The contrarian take: the dual-classification system is not as broken as it looks
The dual classification feels arbitrary, but it serves a real purpose: it lets cosmetic products with active ingredients exist as cosmetics when their use is genuinely cosmetic, and as drugs when their use is genuinely therapeutic. A salicylic acid toner for general exfoliation is a different use case than a salicylic acid acne medicine, even though the molecule is the same.
The alternative (every active-ingredient skincare product becomes a drug) would slow innovation and price most actives out of consumer reach. The system as it stands is awkward but functional. The brands that misuse it (cosmetic claims for drug effects) are the actual problem, not the structure.
Real numbers
The FDA issued 47 warning letters to cosmetic companies in fiscal year 2023 specifically citing unapproved drug claims, according to the agency’s enforcement reports. Common targets were anti-aging products claiming wrinkle treatment, scalp products claiming hair-loss treatment, and acne products with unapproved active concentrations.
The FDA’s “is it a cosmetic, drug, or both” guidance is the most accessible public explanation of the line. The guidance walks through the claim-based classification logic with examples and is one of the more readable pieces the agency has produced.
FAQ
Why is sunscreen a drug in the US but a cosmetic in Europe? Regulatory history. The US classified sunscreen as a drug in the 1970s based on its protective function; the EU classifies it as a cosmetic. The practical consequence is that EU sunscreens can include newer filter ingredients (e.g., Tinosorb) that have not been approved under the US OTC monograph.
Can a cosmetic make any health-related claim? Only structural or appearance-related ones. “Moisturizes” is fine. “Treats dry skin disease” crosses into drug territory.
What about retinol products that claim to “improve” skin? “Improve appearance” is cosmetic. “Treat wrinkles” is drug-leaning. The retinol category is one of the most carefully copywritten in skincare because the active is on the borderline.
Are prescription tretinoin and OTC retinol the same thing? Same molecular family, different forms. Tretinoin is retinoic acid, the biologically active form, available only by prescription. Retinol is a precursor that the skin converts to retinoic acid; OTC and cosmetic. Both work; tretinoin is faster and stronger.
Why is hydroquinone now restricted? The FDA reclassified hydroquinone products under stricter drug regulation in 2020, citing safety concerns about ochronosis and unsupervised long-term use. Products containing hydroquinone above 2 percent now require prescription; lower-concentration OTC products were temporarily allowed but face increased scrutiny.
For related context, see who reviews FDA cosmetic claims, the FTC’s role in beauty marketing, and why hypoallergenic is not regulated.
Tag hub: More on skincare myths and regulation
Sources
Federal Food, Drug, and Cosmetic Act, 21 USC 321-399i. US Food and Drug Administration, “Is It a Cosmetic, a Drug, or Both?” guidance document, 2023. Modernization of Cosmetics Regulation Act of 2022, Public Law 117-328.