Persons working in a military unit in Boden and persons connected to the Department of Sports Medicine in Umeå were invited to participate in this study. Only persons older than 18 years was included in the study. The persons included received one bottle of study medicine, a home protocol (WURSS 21) and a viral sampling kit. Whenever the included persons were sure that they had received an episode of common cold they were told to perform a viral sampling from the nose, fill in the protocol and start to use the nasal spray several times daily for one week. The treatment was either a) a saline solution with 5% glucose or b) a saline solution with 200U/ml of glucose oxidase and 5%glucose (active treatment group). The combination of glucose oxidase and glucose produces an acid environment, imitating the effect of the normal nasal flora and Human Rhinoviruses are sensitive to an acid environment. After one week of treatment and daily records of the WURSS 21 protocol the persons returned the spray bottles (Bag-on-Valve), the virus vials and the protocols.