Scientists from the University of Bath and King’s College London (KCL) suggest that hydrogen sulfide, the volcanic gas known for its rotten egg smell, could lead to a faster-acting, lower side-effect treatment for stubborn nail infections.
Nail infections are usually caused by fungi, though bacteria can sometimes be responsible. They are extremely common, affecting between 4 and 10 percent of people worldwide, and becoming even more prevalent with age—nearly half of those over 70 experience them.
While often seen as minor, these infections can cause serious complications in people with underlying health issues, such as diabetes or weakened immune systems. Unfortunately, they are among the most stubborn conditions to treat effectively.
Doctors typically rely on two main approaches: oral antifungal medications and topical treatments that are applied to the nail surface. Oral antifungals can work within two to four months and tend to be fairly effective, but they may also trigger side effects, particularly in patients with other medical conditions.
Topical medications are safer for most patients but act much more slowly. In some cases, results can take years, and even then, the infection may return or fail to clear completely. This difficulty arises because it is challenging for drugs to pass through the tough nail structure to reach the source of infection underneath.
Even the best topical options achieve relatively low success rates. For that reason, researchers are actively seeking new therapies that are both safe and powerful enough to eliminate microbes hidden deep within the nail.
Hydrogen Sulfide Shows Promise
A team from the University of Bath and King’s College London has now found that hydrogen sulfide (H₂S), a small, naturally occurring gas, could be developed into a promising new treatment.
Previous work has shown that it penetrates the nail plate far more efficiently than existing topical drugs, and now the team has demonstrated that it has strong antimicrobial activity against a wide range of nail pathogens, including fungi that are resistant to common antifungal treatments.
In laboratory tests, the team used a chemical that breaks down to release the Hydrogen sulfide gas and found that it acts in a unique way, disrupting microbial energy production and triggering irreversible damage, ultimately killing the fungi.
The research is published in Scientific Reports.
Expert Insights and Future Potential
Dr Albert Bolhuis, from the University of Bath’s Department of Life Sciences, said: “Thanks to its ability to efficiently reach the site of infection and its novel mode of action, we believe that a topically applied medicine containing hydrogen sulphide could become a highly effective new treatment for nail infections, which avoids the limitations of current therapies.
“Our research lays the foundation for a compelling alternative to existing treatments, with the potential to improve outcomes for patients suffering from persistent and drug-resistant fungal nail infections.”
Hydrogen sulphide is known for its pungent smell of rotten eggs, and has some toxicity, however, researchers believe the amounts required are well below toxicity levels and the correct formulation will limit any unpleasant odors.
The research has so far only been done in vitro, but the team hopes to develop a treatment that could be used in patients in the next five years.
Professor Stuart Jones, Director of the Centre for Pharmaceutical Medicine Research at KCL said: “We are looking forward to translating these findings into an innovative topical product that can treat nail infection.”
Reference: “Antimicrobial effects and mechanisms of hydrogen sulphide against nail pathogens” by Fritz Ka-Ho Ho, Alyaa Al-Tabtabai, Sara M. Nasereddin, Osamah S. Malallah, Mark A. Lindsay, Stuart A. Jones and Albert Bolhuis, 31 October 2025, Scientific Reports.
DOI: 10.1038/s41598-025-22062-7
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