Have any supplements been studied for sinusitis?

European guidelines hold that supplements with some benefit for the common cold can also be tried for acute sinusitis, for example zinc, vitamin C, and probiotics.^[1] Other supplements with limited evidence for improving sinusitis symptoms include umckaloabo (Pelargonium sidoides), bromelain (pineapple enzyme), cod liver oil, horseradish root, and andrographis. ^[2] Combination herbal products, often containing Flos magnoliae and Siberian cocklebur fruit, have been studied in China and Taiwan, showing benefit for sinusitis symptoms. However, the generalizability of these results to other geographic locations is unknown.^[3]