loss of sense of smell is known as anosmia and loss of sense of taste is known as aguesia. both are very much interrelated as sense of smell is required for complete sense of taste. there may be many causes such as nasal allergy head injury nasal polyps post viral infection rarely tumors of nose or brain primary investigation for such problem is examination of nose especially with endoscope. once nasal problems are cleared then ct or MRI of nose and brain are required after these investigations diagnosis can be made consult a ENT specialist for further management