Compound W’s main active ingredient is salicylic acid, typically at a 17% concentration in the liquid formula. This acid works by breaking down the tough, built-up skin that forms a wart. Beyond the active ingredient, the product contains several inactive ingredients that help it stick to your skin, dry into a protective film, and penetrate the wart tissue.
The Active Ingredient: Salicylic Acid
Salicylic acid at 17% is the workhorse of Compound W’s liquid and gel formulas. It’s a keratolytic, meaning it dissolves keratin, the protein that makes up the tough outer layers of your skin. Warts are essentially overgrowths of keratin-rich skin caused by the human papillomavirus (HPV), and salicylic acid strips them away layer by layer.
At the molecular level, salicylic acid breaks the sulfur bonds that hold keratin’s protein chains together. A 2024 study using advanced imaging confirmed that even moderate concentrations of salicylic acid cause these sulfur bonds to oxidize and fragment within a week, weakening the wart’s structure at its deepest layers. Each application softens and peels a thin layer of infected tissue, gradually reducing the wart until healthy skin takes its place.
Inactive Ingredients in the Liquid Formula
The inactive ingredients in Compound W liquid are alcohol, camphor, castor oil, collodion, ether, ethylcellulose, hypophosphorous acid, menthol, and polysorbate 80. These aren’t just filler. Each plays a role in getting the salicylic acid where it needs to go and keeping it there.
Collodion is one of the most important. It’s a syrupy solution that dries into a thin, flexible film over the wart after you apply the liquid. This film seals the salicylic acid against the skin, giving it prolonged contact time to penetrate the wart. Ethylcellulose serves a similar purpose, helping the solution form a stable coating.
Alcohol and ether act as solvents. They dissolve the other ingredients into a smooth liquid and then evaporate quickly after application, which is why Compound W dries fast. Camphor and menthol create the mild cooling or tingling sensation you feel on application. Castor oil adds flexibility to the dried film so it doesn’t crack and peel off prematurely. Polysorbate 80 is an emulsifier that keeps all these ingredients blended together in the bottle, and hypophosphorous acid acts as a stabilizer to prevent the formula from breaking down over time.
What’s in the Freeze-Off Version
Compound W also sells a cryotherapy product (Freeze Off) that works completely differently from the liquid. Instead of salicylic acid, it contains a pressurized mixture of liquid dimethyl ether and propane. When you press the applicator against a wart, these chemicals rapidly evaporate and freeze the wart tissue, destroying the infected cells. The FDA has warned that these ingredients are flammable, so you should keep the product away from heat sources and open flames during and after use.
How Long Treatment Takes
Salicylic acid doesn’t remove warts overnight. Clinical trials typically measure results at 12 to 13 weeks, and most treatment protocols call for daily application over a period of up to 8 weeks before expecting significant clearance. Smaller or newer warts (those less than a year old) tend to respond faster. Warts that have been around longer or are thicker may need the full treatment window.
Between applications, soaking the wart in warm water for about five minutes and gently filing away the softened white skin with a pumice stone or emery board helps the next dose penetrate more effectively. Applying a non-petroleum jelly around the wart before treatment protects the healthy skin surrounding it from unnecessary irritation.
Who Should Avoid Compound W
Salicylic acid at this concentration isn’t safe for everyone. You should not use Compound W if you have diabetes or poor blood circulation, because the acid can cause severe redness or ulceration, particularly on the hands and feet where circulation is already compromised.
The product should never be applied to warts on the face, genitals, inside the nose or mouth, or on warts with hair growing from them. It also shouldn’t be used on moles, birthmarks, irritated skin, or any area that’s infected or red. Children and teenagers with the flu or chicken pox should avoid salicylic acid products entirely due to the risk of a rare but serious reaction.