The sudden loss of the sense of smell, known as anosmia, became a widely recognized symptom of COVID-19. This sensory disruption impacts daily life, affecting a person’s ability to enjoy food and detect hazards. While the experience can be disorienting, understanding the mechanisms behind this symptom and the typical recovery patterns can provide perspective.
The Science of Smell Loss
The SARS-CoV-2 virus, responsible for COVID-19, primarily affects the olfactory system by targeting specific cells within the nose. The virus does not typically infect the olfactory neurons, which are the nerve cells directly responsible for detecting odors. Instead, it largely targets the supporting cells, called sustentacular cells, located in the olfactory epithelium. These sustentacular cells maintain the health and function of olfactory neurons.
When the virus infects sustentacular cells, it can lead to inflammation within the olfactory epithelium. This inflammation and damage to the supporting cells disrupt the environment needed for olfactory neurons to function properly. This indirect impact on the olfactory neurons results in the loss or alteration of smell.
Common Recovery Periods
For many individuals, the sense of smell returns within weeks or a few months following COVID-19 infection. Data indicates that approximately 74% of individuals regain their smell within 30 days, with this number increasing to about 86% by 60 days and 90% by 90 days. The median recovery time for smell has been reported at around 14.9 days.
About 96% see their sense of smell return by 180 days (six months). While most recoveries are complete, some individuals may experience partial improvement. For a smaller proportion of people, around 5-10%, smell dysfunction can persist beyond six months. Studies have also shown that about 90% of those who lost their sense of smell or taste from COVID-19 eventually regain it within two years.
Why Recovery Varies
The duration and completeness of smell recovery after COVID-19 can differ among individuals due to several influencing factors. One aspect is the severity of the initial illness; however, smell loss can occur even in mild cases. Age also plays a role, with younger individuals often experiencing initial smell loss.
Biological differences between individuals can affect recovery trajectories. Some research suggests that females may be less likely to report a full recovery of smell compared to males. The presence of other symptoms, such as nasal congestion during the acute phase of the illness, has also been linked to a potentially longer recovery period for smell dysfunction. These varied outcomes highlight the complex interplay of individual responses to the viral infection.
Supporting Your Sense of Smell
For those experiencing prolonged smell loss or altered smells, specific strategies can help support recovery. Smell training, also known as olfactory training, is a method that can encourage the brain to re-engage with and interpret scents. This process involves regularly sniffing a set of distinct odors, typically essential oils, such as rose, lemon, clove, and eucalyptus.
Consistency is important for smell training, often performed twice daily for 10-20 seconds per scent over several months. While sniffing, focusing on the memory associated with each smell can further aid the process. Beyond complete loss, some individuals may experience parosmia, where familiar smells become distorted or unpleasant, or phantosmia, where phantom smells are perceived. These altered perceptions can also benefit from smell training.
If smell loss persists for more than a month or two, or if distorted smells become particularly bothersome, consulting a healthcare professional, such as an ENT specialist, is advisable. They can assess the situation, rule out other causes, and provide guidance on further steps or specialized clinics. While recovery requires patience, proactive measures and professional support can help.