How Kerassentials Works: Getting Antifungals Into a Hard Nail

By Leah CorbinEditor, Kerassentials ReviewUpdated October 21, 20264 min read

The hardest part of treating nail fungus with anything you put on the outside is getting it to the fungus. Kerassentials is built around that problem: small antifungal molecules, oils that spread into the cuticle and under the nail edge, and a routine designed to keep them there.

Why nail fungus is hard to treat

A toenail is a dense plate of keratin, many cells thick, and most nail fungus lives under it, in the nail bed, or inside its lower layers. Dermatophytes, the same fungi that cause athlete's foot, feed on keratin and slowly turn the nail thick, yellow and crumbly. Because the infection sits behind a hard shield, anything applied on top has a long way to travel.

That is why the MedlinePlus page on fungal nail infections describes nail fungus as hard to treat, and why even prescription topicals are applied every day for most of a year. It is also why recurrence is common: a 2020 review in the Journal of the European Academy of Dermatology and Venereology found that topicals have fewer side effects than pills but lower cure rates and longer treatment times, and recommended treating early and keeping shoes and socks clean.

Step 1: antifungal compounds that act several ways

Kerassentials combines a fatty acid active with five essential oils, and each one attacks fungi differently.

• Undecylenic acid is a fatty acid that damages the fungal cell membrane and stops yeast from switching to its invasive, thread-like form.
• Clove oil, mostly eugenol, punches holes in fungal membranes and blocks ergosterol, the building block fungi need for those membranes. Several common antifungal drugs target ergosterol too.
• Tea tree and manuka oils contain terpenes such as terpinen-4-ol that disrupt fungal cell walls and membranes.
• Lemongrass oil contains citral, which is strongly active against Trichophyton in lab tests.
• Lavender oil adds further antifungal activity and a calmer smell.

Hitting fungi in several ways at once is the same logic doctors use when they combine treatments. A review of essential oils for onychomycosis pointed out that fungi rarely build resistance to these complex oil mixtures, which matters because, as the sales page stresses, drug resistance in fungi is a growing worry.

Step 2: getting into the nail

Essential oil molecules are small and fat-soluble, so they can move through the nail plate better than many larger drug molecules. The formula helps them along in three ways:

1. Carrier oils. Jojoba, almond, chia and the other oils spread the actives across the whole nail and wick them into the cuticle and under the free edge, where fungus often starts.
2. Menthol and camphor. Both are known to help other ingredients pass through skin. In the VapoRub case series, researchers suggested this is part of why the ointment helped toenails.
3. Filing. The label tells you to file the nail surface with an emery board. A thinner, rougher nail lets more oil through. Podiatrists use the same idea when they thin thick nails before treatment.

Step 3: keeping the area healthy

Fungal nails usually come with dry, cracked skin around them, and cracks let fungi and bacteria in. Aloe vera, vitamin E, flaxseed and the other conditioning oils keep the cuticle and surrounding skin soft and intact. That supports the new nail growing out from the base, which is how a fungal nail actually clears.

Step 4: time and consistency

No topical works in a week. The routine of four applications a day keeps a steady level of active ingredients on the nail. The healthy part of a toenail grows from the base at only about a millimeter and a half a month, so a big toenail needs 12 to 18 months to regrow fully. The company's estimate of 9 to 12 weeks for visible results refers to the first signs: clear growth at the base, softer skin and less itching.

What the research supports, and what it doesn't yet

The clinical evidence for the approach is encouraging but small. Tea tree oil matched clotrimazole in a six-month trial. The VapoRub case series and a 2020 open study of a vitamin E and essential oil nail oil both reported strong results. Lab work on clove, lemongrass, manuka and undecylenic acid is consistent.

What is missing is a large trial of Kerassentials itself. That is common for products in this category, and it is why we rate it on the strength of its ingredients and its refund terms.

Where Kerassentials fits

Kerassentials makes the most sense for mild to moderate cases: discoloration or thickening on one or a few nails, without pain or redness. For those, a daily topical is a sensible first step. More severe or widespread infections, or anyone with diabetes, should start with a doctor; the American Podiatric Medical Association has a find-a-podiatrist tool.

Our full score is in the Kerassentials review, and the routine itself is on how to use Kerassentials.

How it compares with prescription topicals

Prescription topicals such as efinaconazole and tavaborole are single-drug solutions applied once a day for 48 weeks. They are designed to penetrate the nail plate and have large trials behind them. Kerassentials takes a multi-ingredient approach in an oil base and is applied more often. It costs less than many prescription topicals without insurance and needs no doctor's visit, which is why many people try it first for a mild case.

Questions about how it works