Smell Changes & Efficacy of Nasal Theophylline

This study evaluates the efficacy and safety of nasal theophylline irrigation in treating smell loss related to a viral respiratory infection. Half the participants will undergo nasal theophylline irrigation treatment while the other half will undergo placebo nasal irrigation with saline alone. All participants will have their sense of smell tested before and after 6 weeks of treatment. All participants will also be regularly asked about any potential side effects related to treatment. In addition, the first 10 participants will have their blood drawn to measure their theophylline level after 1 week of starting treatment to ensure it is not abnormally elevated.