Smell Changes & Efficacy of Nasal Theophylline

Inclusion Criteria: * Subjective or clinically diagnosed olfactory dysfunction of 6 months to 36 months duration after a presumed viral upper respiratory infection * Ability to read, write, and understand English Exclusion Criteria: * Dependence on theophylline for comorbid conditions such as asthma and chronic obstructive pulmonary disease * History of an allergic reaction to theophylline or other methylxanthines * Prior sinonasal or anterior skull base surgery * Nasal polyposis * History of neurodegenerative disease (ie. Alzheimer's dementia, Parkinson's disease, Lewy body dementia, frontotemporal dementia) * Pregnant or breastfeeding mothers * Current use of medications with significant (≥40%) interactions with theophylline, which include cimetidine, ciprofloxacin, disulfiram, enoxacin, fluvoxamine, interferon-alpha, lithium, mexiletine, phenytoin, propafenone, propranolol, tacrine, thiabendazole, ticlopidine, and troleandomycin