Smell Retraining Therapy (SRT) is an effective method of regaining the sense of smell when weakened due to conditions such as viral infection or head trauma. The treatment involves introducing different smells to the nose for a prolonged period so that the olfactory system creates memories associated with each scent. This is especially beneficial if there were aromas you used to enjoy before your sense of smell was weakened. A good approach is to start using at least four strong scents, which can help maximize your chances of success in regaining the pleasure and appreciation that comes with a heightened sense of smell.