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.