Serratiopeptidase is a proteolytic enzyme originally isolated from the bacterium Serratia marcescens. It has been used in some countries, especially in Asia and Europe, as an anti-inflammatory agent for various conditions, including sinus infections (sinusitis). The rationale for its use in sinus infections is based on its purported ability to break down inflammatory mediators, thin mucus, and reduce swelling, thereby potentially facilitating sinus drainage and alleviating symptoms.

There is limited scientific evidence supporting serratiopeptidase for sinus infection. Several small clinical trials and observational studies have suggested that serratiopeptidase may reduce symptoms such as pain and swelling in patients with ENT (ear, nose, and throat) conditions, including sinusitis. For example, some studies have reported faster improvement in sinus symptoms and reduction in viscosity of nasal secretions when serratiopeptidase is used as an adjunct to standard therapy. However, most studies are small, lack rigorous methodology, or are not double-blind and placebo-controlled. The quality of evidence is therefore considered low to moderate.

Major clinical guidelines do not recommend serratiopeptidase as a standard treatment for sinus infection, and it is not approved for this use in the United States. While there is some scientific basis and preliminary evidence for its use, more robust, high-quality clinical trials are needed to confirm efficacy and safety. Thus, it receives a rating of 2 on the evidence scale.