A combination of over-the-counter products can thwart the duplication of  SARS-CoV-2, the virus that causes COVID-19, researchers at the University of Florida and the University of Saskatchewan, have discovered.

Diphenhydramine, an antihistamine used for allergy symptoms, and lactoferrin, a protein found in cow and human milk used as a supplement to treat stomach and intestinal ulcers, have proven effective in retarding duplication of the virus during tests on monkey cells and human lung cells.

The findings, published in the journal Pathogens and announced in a UF press release Monday, could eventually lead to the development of a product that could be used in the fight against COVID-19, said David A. Ostrov, an immunologist and associate professor in the UF College of Medicine's department of pathology, immunology and laboratory medicine.

People should not self-medicate or use the products as a COVID-19 prevention or treatment, the press release warned.

Osrtov already knew diphenhydramine was potentially effective against the SARS-CoV-2 virus from his previous research efforts, after researchers presented unpublished data at a Global Virus Network COVID-19 task force meeting on federally approved compounds that were successful in reducing SARS-CoV-2 replication activity, including lactoferrin.

Ostrov decided to pair the two products, both of which are available without a prescription, to see what occurred.

Individually, the compounds each slowed SARSCoV-2 virus replication by about 30%. When paired together, though, the compounds reduced virus replication by 99%.

In reaching their conclusions, scientists targeted the sigma receptors, which the virus uses to replicate itself.

Scientists from UF's Emerging Pathogens Institute, College of Pharmacy and Clinical and Translational Science Institute, the University of Saskatchewan and the Saskatchewan Cancer Agency collaborated on the research.