DMSO (dimethyl sulfoxide) is used for toenail fungus primarily as a penetration enhancer, helping antifungal agents pass through the hard nail plate that normally blocks topical treatments. It is not an FDA-approved standalone treatment for nail fungus, but it has shown measurable antifungal activity on its own and stronger results when paired with an active antifungal ingredient. Here’s what the research supports and how people actually apply it.
Why DMSO Works on Nail Fungus
The toenail plate is a dense barrier made of tightly packed layers of keratin held together by lipid (fat) structures. Most topical antifungals struggle to penetrate deep enough to reach the fungal infection underneath. DMSO solves this by disrupting those lipid layers. At higher concentrations, it shifts the lipids from a tightly ordered, gel-like state into a looser, more fluid state. Think of it like softening a wax seal so substances can pass through. DMSO also interacts with the keratin protein itself, creating additional pathways for whatever antifungal you’re pairing with it.
This penetration-enhancing effect is why DMSO shows up in compounded pharmacy formulations and clinical research, not as the star ingredient, but as the vehicle that makes the star ingredient effective.
DMSO Alone vs. DMSO With an Antifungal
A pilot study comparing 30% DMSO cream alone against 30% DMSO cream containing an antifungal drug found a meaningful difference. The DMSO-only group achieved a 44% mycological cure rate (meaning lab tests confirmed the fungus was gone), while the group using DMSO plus the antifungal hit 80%. The clinical cure rate, based on how the nail actually looked, was 22% for DMSO alone versus 70% for the combination.
So DMSO by itself does have some antifungal effect, likely because it disrupts fungal cell membranes the same way it disrupts the nail’s lipid barrier. But combining it with an antifungal roughly doubles your chances of clearing the infection. This is the core takeaway: DMSO is most effective as a carrier, not a cure on its own.
What to Pair It With
Clinical and compounding pharmacy formulations have used DMSO with several antifungal agents. One well-documented combination is 1% povidone-iodine in a solution containing 44% pharmaceutical-grade DMSO, prepared by licensed compounding pharmacies. Other studies have tested DMSO at 30% concentration combined with antifungal drugs in cream form.
Some people use DMSO as a carrier for over-the-counter antifungals or natural antifungal agents like tea tree oil. While this approach hasn’t been studied as rigorously, the logic is sound: DMSO will enhance penetration of whatever you dissolve in it. The critical point is that “whatever you dissolve in it” matters enormously, because DMSO pulls nearly anything it contacts through your skin and nail.
How to Apply It Safely
DMSO’s greatest strength is also its biggest safety concern. Because it carries substances through biological barriers so effectively, any contaminant on your skin, your hands, or in the DMSO solution itself will be pulled into your body. This makes preparation and cleanliness non-negotiable.
Before applying, wash your feet and hands thoroughly with plain soap and water. Make sure the nail and surrounding skin are completely clean and free of any lotions, nail polish, dirt, or residue. Use only pharmaceutical-grade (USP-grade) DMSO, not industrial-grade products sold for use as solvents. Use clean glass or ceramic containers and applicators, as DMSO can dissolve certain plastics and carry those chemicals into your skin.
Apply the DMSO solution directly to the affected toenail using a clean cotton swab, dropper, or small brush. Cover the entire nail surface, including the edges and the area where the nail meets the skin. Let it air dry completely before putting on socks or shoes. Most protocols call for once or twice daily application.
How Long Treatment Takes
Toenails grow slowly, roughly 1 to 2 millimeters per month. Even if the fungus is killed quickly, you won’t see a fully clear nail until the damaged portion grows out entirely, which can take 6 to 12 months for a big toenail. Expect to apply the solution daily for several months before you can judge whether it’s working. The first sign of progress is typically a band of healthy-looking nail growing in from the base, pushing the discolored or thickened portion toward the tip.
If you see no change after three to four months of consistent use, the formulation or approach likely isn’t strong enough for your infection.
Side Effects to Expect
DMSO causes predictable side effects, most of them mild but worth knowing about before you start.
- Garlic or oyster-like breath: Your body converts some of the DMSO into a sulfur compound that you exhale through your lungs. About 10% of people using DMSO on the skin notice this. It can appear within hours of application and may persist for a day or two.
- Burning or stinging: The most common skin reaction, reported in roughly 16% of users in clinical studies. It typically lasts only minutes.
- Skin dryness, scaling, or irritation: Reported in about 15% of users. The skin around the nail may become dry or flaky with repeated daily application.
- Redness: Mild redness at the application site occurs in about 9% of users.
- Itching: Around 6% of users report itching near the treated area.
Most of these reactions are transient and resolve on their own. However, some people in clinical studies experienced reactions severe enough to stop treatment. If you develop persistent blistering, intense pain, or a spreading rash, discontinue use.
Concentrations Used in Practice
Research and pharmacy formulations have used DMSO at concentrations ranging from 30% to 44%. Higher concentrations enhance penetration more effectively but also increase the likelihood of skin irritation. A 30% DMSO solution is a common starting point in clinical research. The compounded povidone-iodine preparation that has been used in practice contains 44% DMSO, which sits at the higher end.
If you’re mixing a solution yourself, starting at a lower concentration (around 30%) and increasing only if you tolerate it well is a reasonable approach. Pure, undiluted DMSO (99.9%) applied directly to the nail is more likely to cause burning, dryness, and skin breakdown around the nail folds.
Limitations Worth Knowing
DMSO for toenail fungus exists in a gray area. It is not FDA-approved for treating nail fungus, and no large-scale clinical trials have established a standard protocol the way they have for prescription antifungals. The studies that exist are small pilot studies or case reports. The 44% and 80% cure rates mentioned earlier came from a study of only 19 participants, which is too small to draw definitive conclusions.
Compounded DMSO formulations are available through some pharmacies, typically with a prescription. Over-the-counter DMSO is sold as a solvent and is not regulated as a medication, which means purity and quality vary between products. If you go this route, look specifically for USP-grade DMSO with a purity of 99.9%, sold for pharmaceutical or research use rather than industrial purposes.