Our senses of taste and smell give us great pleasure. Taste helps us enjoy food and beverages. Smell lets us enjoy the scents and fragrances like roses or coffee. Taste and smell also protect us, letting us know when food has gone bad or when there is a gas leak. They make us want to eat, ensuring we get the nutrition we need.
People with taste disorders may taste things that aren't there, may not be able to tell the difference in tastes, or can't taste at all. People with smell disorders may lose their sense of smell, or things may smell different. A smell they once enjoyed may now smell bad to them.
Many illnesses and injuries can cause taste and smell disorders, including colds and head injuries. Some drugs can also affect taste and smell. Most people lose some ability to taste and smell as they get older. Treatment varies, depending on the problem and its cause.
NIH: National Institute on Deafness and Other Communication Disorders