Not all antifungal products work the same way. The active ingredient helps determine how the product works, what conditions it is labeled to treat, and what formats it comes in. Understanding the differences between the major antifungal drug ingredients helps you choose the right product for your situation and use it effectively.
This guide covers the five most common OTC antifungal drug ingredients (tolnaftate, clotrimazole, terbinafine, butenafine, and miconazole) as well as pharmaceutical-grade essential oils used in non-medicated antifungal cleansing products. For each, we cover how it works, what it treats, and what formats it comes in.
How Antifungal Ingredients Work
Fungi are not bacteria. They have a fundamentally different cell structure, which is why antibiotics do not work against fungal infections and why antifungal drug ingredients are formulated specifically to target fungal biology.
Most OTC antifungal drug ingredients work by disrupting the fungal cell membrane. Fungal cell membranes depend on a compound called ergosterol, which plays a role similar to cholesterol in human cells. Many antifungal agents interfere with ergosterol production, which weakens the membrane and causes the organism to die or stop reproducing.
Tolnaftate differs from some other OTC antifungal ingredients, which is one reason it is useful to understand each ingredient rather than treating all antifungals as interchangeable.
Tolnaftate
How it works
Tolnaftate inhibits an enzyme called squalene epoxidase, which fungi need to produce ergosterol. Without ergosterol, the fungal cell membrane cannot maintain its structure. Tolnaftate is fungistatic at lower concentrations, meaning it stops fungal growth, and fungicidal at higher concentrations, meaning it kills the fungus directly. Tolnaftate's mechanism is specific to dermatophytes, the fungi responsible for athlete's foot, ringworm, and jock itch, and does not have broad-spectrum activity against the wider range of fungi that make up the skin's normal microbiome.
What it treats
Tolnaftate is FDA-approved for the treatment of most athlete's foot (tinea pedis), ringworm (tinea corporis), and jock itch (tinea cruris). It is not effective against yeast-based infections such as candidiasis or tinea versicolor.
Common formats
Tolnaftate is available in creams, powders, sprays, and medicated bar soaps. It is one of the few OTC antifungal drug ingredients commonly formulated into bar soap form, which makes it useful for athletes who want a treatment product they can use as part of their regular shower routine.
Defense Soap product
Defense Antifungal Medicated Bar Soap contains tolnaftate 1% and is an FDA-registered OTC drug product labeled for the treatment of most athlete's foot, ringworm, and jock itch when used as directed.
Clotrimazole
How it works
Clotrimazole belongs to the azole class of antifungals. It works by inhibiting an enzyme called lanosterol 14-alpha-demethylase, which is required for ergosterol synthesis. Without sufficient ergosterol, the fungal cell membrane becomes permeable, disrupting the organism's ability to function and reproduce. Clotrimazole is fungistatic at typical therapeutic concentrations.
What it treats
Clotrimazole has a broader spectrum than tolnaftate. It is effective against dermatophytes, the fungi behind athlete's foot, ringworm, and jock itch, as well as against Candida yeast species, which cause conditions like oral thrush and vaginal yeast infections. Topical OTC clotrimazole products are primarily labeled for athlete's foot, ringworm, and jock itch.
Common formats
Clotrimazole is available in a wide range of formats including cream, lotion, solution, spray, ointment, and powder. It is one of the more format-diverse OTC antifungal ingredients available. Vaginal and lozenge formulations also exist for yeast-specific conditions.
Defense Soap product
Defense Antifungal Cream contains clotrimazole 1% and is an FDA-registered OTC drug product. It can be used alongside Defense Antifungal Medicated Bar Soap in a two-step routine: cleanse with the soap, then apply the cream to the affected area.
Terbinafine
How it works
Terbinafine belongs to the allylamine class of antifungals. Like tolnaftate, it inhibits squalene epoxidase, blocking ergosterol production. However, terbinafine is generally considered more potent than tolnaftate and has both fungistatic and fungicidal activity against dermatophytes. It also causes a buildup of squalene inside fungal cells, which is itself toxic to the organism.
What it treats
Terbinafine is widely used against dermatophytes and is commonly used for athlete's foot, ringworm, jock itch, and nail fungus. OTC terbinafine products are typically labeled for athlete's foot and may require shorter treatment periods than tolnaftate or clotrimazole due to their higher potency against dermatophytes.
Common formats
Terbinafine is available OTC as a cream, gel, and spray. Lamisil AT is the most recognizable brand across all three formats. The spray version contains alcohol and should not be applied to the face. It is not available in bar soap form. Oral prescription terbinafine is the standard treatment for nail fungus (onychomycosis), where topical products generally cannot penetrate deeply enough to be effective.
Butenafine
How it works
Butenafine is a benzylamine antifungal, structurally related to the allylamine class. Like terbinafine, it inhibits squalene epoxidase, blocking ergosterol production and causing a toxic buildup of squalene inside fungal cells. This double mechanism makes butenafine fungicidal rather than fungistatic. Butenafine also has anti-inflammatory properties, which may be useful when fungal skin infections are accompanied by visible inflammation.
What it treats
Butenafine is effective against dermatophytes responsible for athlete's foot, ringworm, and jock itch. It also covers tinea versicolor, a yeast-related condition that causes patches of discolored skin, which is a condition that tolnaftate does not address. Research comparing butenafine to clotrimazole suggests butenafine may achieve faster early results, though outcomes at four and eight weeks are broadly comparable between the two.
Common formats
Butenafine is available OTC as a 1% cream, most recognizably as Lotrimin Ultra. It is applied once or twice daily depending on the condition and treatment period. It is not available in soap or powder form.
Miconazole
How it works
Miconazole is another azole antifungal, working by the same general mechanism as clotrimazole, inhibiting ergosterol synthesis by blocking lanosterol 14-alpha-demethylase. Miconazole also disrupts the fungal cell membrane directly and inhibits certain enzymes involved in fungal metabolism, giving it a slightly broader mechanism than clotrimazole alone.
What it treats
Miconazole is effective against dermatophytes and Candida species. It is commonly used for athlete's foot, ringworm, jock itch, and yeast-related skin and vaginal infections. It is also used in some formulations targeting tinea versicolor, a yeast-related condition that causes patches of discolored skin.
Common formats
Miconazole is available in creams, powders, sprays, and vaginal formulations. It is most commonly used in cream, powder, and spray formats depending on the condition being treated.
Pharmaceutical-Grade Essential Oils as Non-Drug Antifungal Ingredients
Tea tree oil and eucalyptus oil are not OTC drug ingredients and cannot carry drug treatment claims. However, they are widely used in skin-cleansing products and are known for their natural antimicrobial and antifungal properties.
Tea tree oil (Melaleuca alternifolia)
Tea tree oil has been extensively studied for antimicrobial activity. Its primary active compound, terpinen-4-ol, has demonstrated antifungal activity in laboratory research against dermatophytes including Trichophyton rubrum and Trichophyton mentagrophytes, the fungi most commonly responsible for athlete's foot and ringworm. Pharmaceutical-grade tea tree oil contains standardized concentrations of terpinen-4-ol that are meaningfully higher than cosmetic or food-grade formulations.
Eucalyptus oil (Eucalyptus globulus)
Eucalyptus oil is used alongside tea tree oil in Defense Soap's formulations for its complementary antimicrobial properties. Research on eucalyptus oil's antifungal activity is less extensive than that on tea tree oil, but it is well-established as an antimicrobial ingredient with a long history of use in health and hygiene applications.
Products formulated with pharmaceutical-grade essential oils support daily skin hygiene and may appeal to people who want a more intentional cleansing routine. They are not substitutes for medicated antifungal treatment when an active infection is present.
Comparing the Major OTC Antifungal Drug Ingredients
All five major OTC antifungal drug ingredients are effective against the dermatophytes responsible for the most common fungal skin infections. The key differences come down to spectrum of activity, potency, available formats, and treatment duration.
- Tolnaftate is specific to dermatophytes, available in soap form, and a practical option for athletes who want a treatment product they can use in the shower. It does not cover yeast-based infections.
- Clotrimazole covers both dermatophytes and Candida, making it useful for a broader range of fungal conditions. Commonly used as a cream applied directly to affected skin.
- Terbinafine is generally considered the most potent OTC option against dermatophytes, often with shorter treatment durations. Primarily available as a cream, gel, or spray.
- Butenafine is fungicidal against dermatophytes and also covers tinea versicolor. It has the added benefit of anti-inflammatory properties. Available OTC as a 1% cream.
- Miconazole covers dermatophytes and Candida with a slightly broader mechanism than clotrimazole. Most commonly found in cream, powder, and spray formats.
If you have a confirmed or suspected dermatophyte infection, such as athlete's foot, ringworm, or jock itch, any of these five ingredients when used consistently and for the full treatment period can be effective. If you are unsure which condition you have, or if your symptoms are not responding to OTC treatment after the recommended period, see a medical professional.
One Important Note on Nail Fungus
These OTC antifungal drug ingredients are generally not labeled for effective treatment of scalp or nail fungus. Nail fungus (onychomycosis) requires prescription-strength treatment, typically oral terbinafine or another prescription antifungal, because topical products cannot penetrate the nail plate deeply enough to reach the infection. If you are dealing with nail fungus, OTC products are not the right tool and a physician visit is warranted.
Defense Soap FDA-Registered Antifungal Products
- Defense Antifungal Medicated Bar Soap: Tolnaftate 1%. FDA-registered OTC drug product. Triple-milled bar soap format. Labeled for treatment of most athlete's foot, ringworm, and jock itch when used as directed.
- Defense Antifungal Cream: Clotrimazole 1%. FDA-registered OTC drug product. Topical cream for direct application to affected skin. Often used alongside the medicated bar soap as part of a two-step routine.
For a broader overview of antifungal soap as a product category, see What Is Antifungal Soap. For condition-specific guides, see our Fungal Skin Infections Guide, Ringworm Guide, Athlete's Foot Guide, and Jock Itch Guide.
This article is for educational purposes only and is not medical advice. For diagnosis or treatment guidance, consult a qualified healthcare professional. See our full disclaimer.