Nikhil Prasad Fact checked by:Thailand Medical News Team Apr 22, 2026 1 hour, 33 minutes ago
Medical News: A widely available cough medicine is now drawing serious attention after new research suggests it could significantly reduce the risk of COVID-19 infection when used preventively. The study, led by scientists in Bulgaria, explored the effects of bromhexine hydrochloride, a common over-the-counter drug, and found striking reductions in infection rates among users.
Common cough medicine shows unexpected potential in reducing COVID-19 infection risk
Simple Drug with a Surprising Role
Researchers from the Research Institute of Innovative Medical Science and the Department of Medical Chemistry and Biochemistry at the Medical University-Sofia, along with experts from University Hospital Alexandrovska, the Faculty of Public Health, and the Faculty of Pharmacy at the same university, conducted the study involving 125 participants who used bromhexine as a preventive measure.
Bromhexine is traditionally used to treat coughs by thinning mucus, but scientists believe it may also block a key protein called TMPRSS2 that the coronavirus uses to enter human cells. By interfering with this entry point, the drug may stop infection before it even begins.
Sharp Drop in COVID-19 Infections
Before taking bromhexine, more than 62 percent of participants reported having had COVID-19. After using the drug prophylactically, that number dropped dramatically to just over 11 percent. This sharp decline suggests a strong protective effect.
The findings were consistent across different groups. Among vaccinated individuals, infection rates fell from about 48 percent to under 4 percent. Unvaccinated individuals also saw a major drop, from over 66 percent to around 13 percent. Interestingly, prior infection did not significantly change the outcome, indicating the drug’s effect may be independent of natural immunity.
Duration Matters More Than Dose
One of the most important discoveries was that how long the drug is taken appears to matter more than how much is taken. Individuals who used bromhexine for longer periods saw the greatest protection. Reinfection rates dropped from over 33 percent in those using it for 10 days or less to just 2.6 percent in those taking it for 30 days or more.
This
Medical News report highlights that the protective effect seems to build over time, supporting the idea that consistent use during high-risk periods may offer the strongest defense.
How It Works Inside the Body
The drug appears to act at multiple stages. Primarily, it blocks the virus from entering cells by inhibiting TMPRSS2. It may also interfere with viral replication and reduce inflammation in the respiratory tract. These combined effects could explain why even those who became infected experienced milder symptoms. The study also noted that bromhexine has a long history of safe use, is inexpensive, and is widely available, making it an attractive candidate for large-scale preventive strategies.
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Limitations and Caution
Despite the promising results, the study was observational and based on self-reported data, which can introduce bias. The relatively small sample size and lack of controlled clinical conditions mean the findings should be interpreted carefully.
Researchers emphasized that more rigorous, randomized clinical trials are needed to confirm the results and determine optimal dosing strategies.
Conclusions
The study provides compelling early evidence that bromhexine hydrochloride could play a meaningful role in preventing COVID-19 infections, particularly when used consistently over longer periods. Its apparent ability to reduce infection rates regardless of vaccination status or prior exposure suggests it may complement existing preventive measures rather than replace them. However, until larger and more controlled studies are conducted, it should not be seen as a standalone solution but rather as a promising candidate worthy of further scientific validation and global attention.
The study findings were published in the peer reviewed journal: Immunity, Inflammation and Disease.
https://onlinelibrary.wiley.com/doi/10.1002/iid3.70438
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https://www.thailandmedical.news/news/old-cough-drug-shows-power-against-new-covid-19-variants
https://www.thailandmedical.news/news/bromhexine-shows-strong-potential-against-new-covid-19-strains
https://www.thailandmedical.news/news/bromhexine-and-high-dose-colchicine-can-prevent-and-treat-flu-as-well-as-covid-19-infections
https://www.thailandmedical.news/news/bromhexine-shows-promise-as-prophylactic-shield-against-flu-infections
https://www.thailandmedical.news/news/covid-19-news-randomized-clinical-trial-shows-that-n-acetylcysteine-and-bromhexine-prevents-covid-19-disease-severity
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