Cayenne is a nightshade similar to other peppers, tomatoes, and potatoes. What brings the heat to cayenne pepper is its capsaicin. The capsaicin gives cayenne its medicinal properties (per WebMD). According to a 2021 article in the Annals of the Romanian Society for Cell Biology, capsaicin in peppers such as cayenne can improve your gut health, digestion, and metabolism. It also has antibacterial properties and can reduce fever. Capsaicin interacts with cells that are important for our immune response.
Capsaicin might also affect the flu in your system, according to a 2023 article in Nutrients. A flu virus needs a particular enzyme to spread and infect other cells in your respiratory system. Capsaicin might activate neurons in your respiratory tract that can inhibit this enzyme. This compound in cayenne pepper might also help stop various strains of a virus found in West Africa from entering cells by blocking key processes of the virus.