The experience of food turning bland and unappealing during a respiratory infection is a common symptom of the common cold. This temporary change often leads people to believe their tongue has stopped working, but the scientific explanation is more complex. The diminished enjoyment of food is not a failure of the taste buds themselves. Instead, it is a consequence of how a cold interferes with the body’s entire sensory system, specifically the sense of smell.
The Difference Between Taste and Flavor
What people commonly refer to as “taste” is scientifically defined as “flavor,” which is a multi-sensory experience. True taste, or gustation, is limited to five basic sensations detected by the receptors on the tongue: sweet, sour, salty, bitter, and umami (savory). These sensations are relatively crude on their own, allowing you to identify only the chemical properties of a substance.
Flavor is a complex perception created by combining true taste with input from the sense of smell, or olfaction. When you eat, volatile molecules from the food travel up the back of your throat into the nasal cavity, where specialized cells detect them. This olfactory contribution accounts for a large portion of what we perceive as flavor, with some studies suggesting smell contributes up to 80% of the overall experience. When a cold interferes with the ability to smell, the perception of a food’s complex profile is lost, leaving only the basic taste sensations.
How Colds Block the Sense of Smell
The primary reason food tastes bland during a cold is the temporary loss of smell, a condition medically known as temporary anosmia. A cold is caused by a viral infection that triggers an inflammatory response in the nasal passages. This inflammation causes the lining of the nose to swell and initiates increased mucus production.
The swelling and excessive mucus physically obstruct the nasal cavity, creating a barrier to the olfactory receptors. These receptors are located high up in the roof of the nose, in a small area called the olfactory cleft. For a food’s aroma to be perceived, volatile odor molecules must travel through the nasal passages and reach this area. When the nose is congested, these molecules cannot reach the receptors, preventing signals from being sent to the brain.
What Happens to the Taste Buds During a Cold
While the sense of smell is compromised, the taste buds on the tongue continue to function normally during a common cold. The specialized cells responsible for detecting sweet, sour, salty, bitter, and umami remain intact and active. This is why a person with a cold can still tell that a food item is salty or sweet, even if they cannot discern the nuanced difference between a cherry and a grape.
The cold virus does not typically target or damage the gustatory receptors. Therefore, the problem is not a malfunction of the tongue, but rather a disruption in the communication pathway between the mouth and the nose. The “loss of taste” is actually a loss of the flavor complexity provided by olfaction.
When Loss of Taste Requires Medical Attention
For the common cold, the temporary loss of flavor perception is expected and typically resolves completely once the congestion clears. In most cases, the sense of smell returns within a few days or up to two weeks after the respiratory symptoms have subsided. If your sense of smell and flavor does not return after this period, consult a healthcare professional.
A prolonged or sudden loss of smell without accompanying nasal congestion, fever, or cold symptoms can be a sign of other medical issues. Persistent anosmia may indicate conditions such as nasal polyps, chronic sinus issues, or a problem with the neural pathways. Seeking medical guidance is important if the loss is unexplained or if it lingers for weeks after the cold has run its course.