A combination of cannabidiol (CBD) and the anti-inflammatory drug diclofenac killed certain types of bacteria more effectively than either compound alone, according to a new study published in the International Journal of Molecular Sciences.

Researchers from the National University of Science and Technology POLITEHNICA Bucharest and the University of Bucharest evaluated the antibacterial activity and biocompatibility of the CBD-diclofenac combination.

The formulation was tested against four bacterial species: Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa.

Researchers found a clear synergistic effect against S. epidermidis, meaning the compounds were more effective together than would be expected based on their individual effects. The combination significantly reduced the concentration needed to inhibit the bacteria.

An additive effect was observed against S. aureus, indicating that the two compounds worked together without producing the stronger synergistic response seen against S. epidermidis.

The combination also killed the bacteria more rapidly than CBD or diclofenac alone. Testing indicated that the treatment was bactericidal, meaning it killed bacteria rather than merely preventing their growth.

However, the formulation showed no antibacterial activity against the two Gram-negative bacteria tested, E. coli and P. aeruginosa.

Researchers also evaluated whether the antibacterial concentration could damage healthy cells. Laboratory testing found that a concentration of 3.906 micrograms per milliliter preserved cell viability and membrane integrity, with cells maintaining a normal appearance.

The findings suggest that combining CBD with diclofenac could provide the basis for a future nonantibiotic antibacterial treatment, particularly against certain Staphylococcus infections.

Researchers said additional testing is needed to further examine the formulation’s safety, effectiveness and potential applications before it could be developed into a medical treatment. They said such combinations may eventually help reduce reliance on conventional antibiotics and limit the doses required to control some bacterial infections.