Secret Clinical Strength is Procter & Gamble's strongest Secret antiperspirant, sold in the US as an invisible solid, a soft solid, a clear gel and a dry spray. The stick, soft solid and gel each list a 20% aluminium zirconium salt on their Drug Facts labels, the most the US over-the-counter rules allow for that family of salts. That makes it a sensible first try for heavy underarm sweating. It isn't the top of the over-the-counter ladder: in the US, 15% aluminium chloride products such as Certain Dri sit above it.
This review is desk research. We read the Drug Facts label for each Secret Clinical version discussed here on DailyMed, the US National Library of Medicine's label database, along with Secret's product page and guidance from the International Hyperhidrosis Society (IHS) and the American Academy of Dermatology (AAD). Nobody at this site has tested the product. It is not medical advice.
Secret Clinical Strength at a Glance
- Maker: Procter & Gamble, Cincinnati
- Formats: invisible solid, soft solid, clear gel, dry spray
- Active: depends on the format (table below)
- Our pick: the Free & Sensitive invisible solid, 2.6 oz, 20% aluminum zirconium tetrachlorohydrex gly
- Pack claims: "100 HR protection" on the front of the pack, and "3X sweat protection" against the wetness protection required of an ordinary antiperspirant on Secret's product page. Both are Procter & Gamble's claims, and we haven't seen the test data behind them.
- Where to buy: Amazon US, where the Free & Sensitive stick was in stock and sold by Amazon.com when we checked on 14 October 2026
Check the formula, pack size, seller and delivery country. Search results may include alternatives.
Which Salt Is in Which Secret Clinical?
The name stays the same across the range, but the active does not. These are the labels we opened:
| Version | Label active | What the label says to do |
|---|---|---|
| Invisible solid (Free & Sensitive, Stress Response) | Aluminum zirconium tetrachlorohydrex gly 20% | "Apply to underarms only. Apply at bedtime" |
| Soft solid (Free & Sensitive, Stress Response) | Aluminum zirconium trichlorohydrex gly 20% | "apply two clicks of product to underarms at bedtime" |
| Clear gel (Stress Response, Completely Clean) | Aluminum zirconium octachlorohydrex gly 20% | "apply 2-3 clicks of product to underarms at bedtime" |
| Dry spray (Stress Response) | Aluminum sesquichlorohydrate | "apply to underarms only" |
Stress Response is a version name used across all four formats. On the labels it doesn't change the active: the Stress Response stick, soft solid and gel carry the same salt at the same 20% as the Free & Sensitive or Completely Clean versions in the same format.
The clear gel, which people search for as Secret Clinical gel, lists water and alcohol denat. in its base. If a stick irritates your skin, the AAD lists trying a different formulation, such as a gel, among the ways to calm it.
The dry spray is a different product. It uses aluminium sesquichlorohydrate, which the monograph caps at 25%, and the Stress Response spray's label prints the strength as "24.7.0%", an apparent misprint we don't treat as a precise figure. Its label gives no time of day.
What "Clinical Strength" Means on a Secret Pack
"Clinical strength" is not a category in the US rules. The FDA's antiperspirant monograph, 21 CFR Part 350, lists each permitted aluminium salt with a ceiling. Aluminium zirconium salts, including all three in the Secret sticks and gels, may go up to 20%. Aluminium chloride is capped at 15% and only as a non-aerosol water-based solution. So Secret's 20% is the ceiling for its salt, and it doesn't compare directly with 15% aluminium chloride. Our guide to how clinical antiperspirants work explains why the salt matters more than the number.
The IHS says clinical strength antiperspirants usually contain up to 20% active ingredient, against 10% in regular formulas, and that they seem to reduce sweat better than traditional over-the-counter antiperspirants with less irritation than prescription products. It names 20% aluminum zirconium tetrachlorohydrex glycine, the salt in the Secret stick, as worth trying before moving to a prescription product.
The monograph also controls the wording on the Drug Facts panel. A label may say "extra effective" only if the product has shown a 30% sweat reduction. The Secret Clinical panels we read list the use as "reduces underarm wetness" and nothing more. The 100-hour figure sits on the front of the pack.
How to Use It: What the Label Says
The invisible solid label says to apply to the underarms only, at bedtime. The soft solid and gel labels say the same and add a number of clicks (see the table). Every label we read carries the same warnings:
- Do not use on broken skin
- Ask a doctor before use if you have kidney disease
- Stop use if rash or irritation occurs
Two points from the guidance bodies help the label work. The IHS says to apply antiperspirant only to completely dry skin, using a towel or a hair dryer on a cool setting if needed, because sweat or water on the skin when you apply it causes irritation and stinging. The AAD adds that you should let it dry completely before going to bed. If you have been swiping it on straight after a morning shower, that is the first thing to change.
Who It Suits
- Heavy everyday underarm sweating, or mild hyperhidrosis. The AAD is clear that non-prescription antiperspirants are only effective for mild hyperhidrosis.
- People who want an ordinary-feeling stick. The invisible solid goes on like a regular antiperspirant, and the IHS describes clinical strength products as less irritating than prescription ones.
- Anyone who has not yet tried a clinical stick properly. Used at bedtime on dry skin, it is a simple test before moving to aluminium chloride.
It suits fewer people if fragrance bothers your skin, if you have already tried a clinical stick correctly without success, or if your problem is your hands or feet. Every label we read says underarms only.
Honest Cons
- "Unscented" with fragrance. Amazon US lists the Free & Sensitive stick's scent as Unscented. The DailyMed label and Secret's own product page both list fragrance among the inactive ingredients. Every Secret Clinical label we opened lists fragrance.
- The big numbers are the maker's. "100 HR" and "3X sweat protection" are Procter & Gamble's claims, and the Drug Facts panels we read do not carry the monograph's "extra effective" wording.
- It is a zirconium salt. The IHS calls aluminium chloride one of the most effective over-the-counter ingredients for controlling hyperhidrosis. Secret Clinical doesn't contain it.
- One name, four formulas. Buying "Secret Clinical" doesn't tell you which salt you get. Read the Drug Facts panel on the pack.
- Not sold in UK shops. See the UK note below.
Secret Clinical vs Degree, Dove and Gillette Clinical
Our clinical strength deodorant comparison read the labels of the other big drugstore clinical sticks. Degree Men Clinical Protection Clean and Dove Clinical + Care Original Clean list the same aluminum zirconium tetrachlorohydrex gly at 20% as the Secret invisible solid. Gillette Clinical, Procter & Gamble's men's line, lists trichlorohydrex gly at 20% in its soft solid, the same as the Secret soft solid. Watch for the exceptions: some Degree Clinical 96H sticks and the Dove Clinical + Care Soft Sensitive list 17% aluminium sesquichlorohydrate instead.
On paper, then, the main clinical sticks are level. We know of no independent head-to-head comparison, so choose on format, scent and price. If fragrance is the problem, Vanicream's antiperspirant lists 20% aluminum zirconium trichlorohydrex gly in a base Vanicream says is fragrance-free.
When to Step Up to 15% Aluminium Chloride
Give Secret Clinical a fair trial: at bedtime, on completely dry skin, for a few weeks. If you are still soaking through, a different 20% zirconium stick is unlikely to change much. The next step without a prescription in the US is aluminium chloride:
- Certain Dri Prescription Strength. Its manufacturer lists aluminium chloride 15% in a roll-on.
- SweatBlock. A single-use wipe; the manufacturer lists aluminium chloride 15%.
- ZeroSweat. The Original roll-on is listed at 15% aluminium chloride, and the maker sells a 12% Aloe Formula for sensitive skin.
Check the formula, pack size, seller and delivery country. Search results may include alternatives.
The IHS notes that aluminium chloride products are among the most effective antiperspirants but can irritate the skin if the instructions are not followed precisely. Follow the directions on the product you buy.
When to Go to Prescription or See a Doctor
If a correctly used 15% product is not enough, a doctor or dermatologist can prescribe a stronger aluminium chloride solution such as Drysol, 20% aluminium chloride hexahydrate, which has been hard to get in autumn 2026. OTC vs prescription antiperspirants sets out what changes, and a dermatologist can also discuss treatments that are not antiperspirants at all.
The NHS advises seeing a GP if excessive sweating stops you getting on with daily life, has lasted six months or more, happens at night, or started while you were taking medicine for another condition.
Can You Buy Secret Clinical in the UK?
Secret is a US brand, and we found no UK high-street stockist. Amazon UK does show some Secret Clinical listings, but the one we checked on 14 October 2026 was sold and dispatched by a third-party marketplace seller rather than Amazon or Secret, so we don't link to it.
UK readers have a stronger option without importing anything. Pharmacies sell 20% aluminium chloride hexahydrate solutions such as Driclor and Anhydrol Forte. Start with our best antiperspirants guide or the strongest antiperspirants in the UK.
Verdict
Secret Clinical Strength is a drugstore clinical range with the same 20% zirconium strength on its stick, soft solid and gel labels as its Degree, Dove and Gillette rivals. The Free & Sensitive invisible solid is our pick of the range, though it is not fragrance-free, despite Amazon listing its scent as Unscented. Use it as the label says, at bedtime on dry underarms. If that is not enough after a few weeks, move to 15% aluminium chloride rather than another zirconium brand, and see a doctor if a 15% product does not help either.
