Many people do not realize that sense of smell directly impacts taste. In fact, loss of taste and smell go hand-in-hand. When one sense is inhibited, the other is affected. Common causes of these symptoms include ordinary illnesses such as a cold, nasal passage congestion, nasal obstruction, breathing problems, allergies and changes in taste bud receptors.
Almost every person knows what it feels like to be sick with a common cold, but many people probably don’t realize that the runny nose and congestion that restrict sense of smell could be what makes food taste funny and seem unappetizing, as can other things, such as side effects from medication. When the nasal passage is congested or obstructed, it can become difficult or impossible for any odor particles to reach the nerves responsible for one's sense of smell. Breathing problems have the same effect. When airways are blocked and an individual is forced to breathe through of his or her mouth, odor particles are impeded and unable to reach the nerves to trigger the sense of smell.
Breathing allergies often cause or worsen breathing problems and cause a loss of taste and smell. When the body realizes that airborne allergens have entered the system, sinuses become irritated, and mucus in the nasal passage attaches to the allergens to prevent transfer to the pulmonary system. As the body tries harder and harder to fight the allergens, more and more mucus is excreted, which causes additional irritation and swelling of the sinuses. This swelling often traps the mucus and allergens, creating a vicious cycle of pain, swelling, pressure and other discomfort. As a result, odor particles are prevented from reaching the proper nerve receptors, and the sense of smell is restricted.
Other factors can hinder sense of smell. Smoking, exposure to second-hand smoke, contact with certain chemicals and the use of specific medications can increase problems with nasal congestion and obstruction, preventing aromas from accessing nerves. Ironically, frequent use of certain nasal decongestants can have the same effect.
Just as smell affects taste, the opposite is often true as well. A variety of conditions can alter an individual’s taste buds, which are the center of taste and in turn contribute to sense of smell. Examples of conditions affecting taste buds include addiction to smoking tobacco, infections in the mouth, cancer of the mouth and vitamin deficiency. Taste buds also change as people age, which is why many older individuals complain of food being bland.
There are many other possible causes of loss of taste and smell. Brain damage and neurological disorders are commonly referenced causes. There are also many other diseases that list loss of taste and smell as common side effects.