Losing your sense of taste and smell at the same time usually happens because the two senses are deeply connected. Most of what you experience as “flavor” is actually smell. When you chew food, odor-rich air travels from the back of your mouth up into your nose, where it activates the same smell receptors used when you sniff something directly. So when your sense of smell goes down, taste seems to vanish with it, even though your tongue may still detect basic sensations like salty, sweet, sour, and bitter.
The causes range from temporary (a cold or sinus infection) to long-lasting (nerve damage or a chronic condition). Understanding what’s behind your specific situation helps determine whether your senses will bounce back on their own or need medical attention.
How Smell and Taste Work Together
Your nose has roughly 1,000 different types of receptor proteins, each designed to bind with specific odor molecules in a lock-and-key fashion. When a match occurs, an electrical signal travels to the brain’s olfactory bulbs and then to areas involved in memory, emotion, and flavor perception. This process happens in two directions: orthonasal smell (breathing in through the nose) and retronasal smell (air pushed from the mouth into the nose while eating). Retronasal smell is what creates the rich, layered experience of flavor, recruiting not just odor but texture and even sound.
When people say food “has no taste,” they almost always mean retronasal smell has been disrupted. The tongue’s taste buds handle only five basic categories. Everything else, the difference between strawberry and raspberry, coffee and chocolate, comes from smell.
Viral Infections Are the Most Common Cause
A cold, flu, or sinus infection is the single most frequent reason people suddenly lose both senses. Swelling and mucus physically block odor molecules from reaching the smell receptors high in your nasal cavity. This type of loss usually clears within a week or two as the infection resolves.
Sometimes, though, a virus does more than cause congestion. It can directly damage the delicate tissue lining the upper nose. With non-COVID respiratory viruses like parainfluenza, the infection can reduce the number of working smell neurons and disorganize the tissue architecture so that the nerve endings no longer reach the surface where they need to be. The body’s own immune response can compound the problem: immune cells release enzymes that are toxic to the smell lining, causing further injury even after the virus itself is gone.
COVID-19 and Smell Loss
SARS-CoV-2 attacks smell through a different mechanism. The virus doesn’t infect the smell neurons directly. Instead, it targets the support cells that surround and nourish those neurons. These support cells carry the ACE2 receptor that the virus uses to enter, while the neurons themselves do not. Once the support cells are damaged, the smell neurons lose the structural and metabolic help they depend on. The virus also disrupts the genetic instructions neurons use to produce smell receptor proteins, which can keep the sense of smell suppressed long after the initial infection clears.
Most people recover their smell within two weeks of a COVID infection. But the timeline can stretch much longer. Up to 28% of people still report smell problems after two years, and roughly 5% continue to have issues beyond three years. Between 5 and 10% of those who lost smell during COVID may never fully recover it.
Nasal Polyps and Structural Blockages
If your smell loss came on gradually rather than suddenly, a physical obstruction could be the cause. Nasal polyps, soft, painless growths on the lining of your nasal passages, are one of the more common culprits. Small polyps often cause no symptoms at all, but as they grow, they block airflow through the nose and prevent odor molecules from reaching the smell receptors. Loss of taste and smell is one of the hallmark symptoms of larger polyps, along with a persistently stuffy nose and reduced ability to breathe through one or both nostrils.
A deviated septum or chronic sinusitis can produce a similar effect. Chronic inflammation keeps the nasal passages swollen and congested, creating a physical barrier between the air you breathe and the smell tissue. These conditions are treatable, and smell often improves significantly once the obstruction is addressed with medication or, in some cases, a procedure to remove polyps or correct structural issues.
Head Injuries and Nerve Damage
A blow to the head, even one that seems minor at the time, can sever or stretch the thin nerve fibers that connect the smell receptors in your nose to the brain. These fibers pass through tiny openings in the skull, making them vulnerable to shearing forces during impact. The loss can be partial or complete and is sometimes not noticed until days or weeks after the injury.
About 30% of people with smell loss after a traumatic brain injury recover naturally over time. Most improvement happens within 6 to 12 months. The chances are better if the loss is partial rather than total. Some people regain the ability to detect strong odors but never fully recover sensitivity to subtler scents.
Medications That Affect Taste and Smell
Prescription and over-the-counter drugs are an underappreciated cause. A recent analysis found that up to half of the top 100 most commonly prescribed medications have the potential to disrupt taste or smell. The drug classes most frequently involved include ACE inhibitors (used for blood pressure), opioid pain medications, certain antibiotics, antithyroid drugs, and HIV medications. Up to 4% of people taking ACE inhibitors experience changes in taste.
Some products cause more dramatic damage. After more than 130 reports of smell loss linked to Zicam intranasal zinc products, the FDA issued a warning that zinc-based nasal sprays may permanently damage the sense of smell. The antidepressant duloxetine was flagged by the FDA in 2021 for potential serious risks of smell reduction. Cancer drugs, particularly a class called protein kinase inhibitors, are especially likely to cause both taste and smell disturbances. Nasal steroid sprays like fluticasone have also been associated with smell changes in hundreds of reported cases.
If you started a new medication around the time your taste and smell changed, the timing is worth mentioning to your prescriber. In many cases, switching to a different drug in the same class can resolve the problem.
Smell Loss as an Early Neurological Sign
A gradual, unexplained decline in smell, especially in people over 60, can sometimes be an early indicator of neurodegenerative conditions like Alzheimer’s or Parkinson’s disease. Research from the National Institute on Aging found that each point of lower performance on a standardized odor identification test was associated with a 22% higher chance of developing mild cognitive impairment. Brain imaging in these studies showed that people with worse smell scores had higher levels of amyloid and tau, the proteins that accumulate in Alzheimer’s, particularly in brain regions tied to both smell processing and memory.
This doesn’t mean that everyone with a fading sense of smell is developing dementia. Many other causes are far more likely. But if smell has been declining gradually over months or years with no obvious explanation like allergies, polyps, or medications, it’s a symptom worth discussing, particularly if memory or thinking changes have accompanied it.
What Recovery Looks Like
Your chances and timeline for recovery depend almost entirely on the cause. Congestion from a cold or sinus infection typically resolves within one to two weeks. Post-viral nerve damage takes longer, with most improvement occurring in the first year. Medication-related loss often reverses after the drug is stopped or changed. Polyp-related loss improves once the obstruction is treated.
Some people recovering from smell loss experience parosmia, a distortion where familiar things smell wrong. Coffee might smell like sewage, or toast like chemicals. This is actually considered a sign that the smell neurons are regenerating, even though the experience is unpleasant. It tends to improve gradually over weeks to months as the nerves finish rewiring.
Smell training is one approach supported by evidence for post-viral cases. It involves sniffing four distinct strong scents (commonly rose, lemon, clove, and eucalyptus) twice daily for several months. The repeated stimulation appears to help damaged neurons recover function more quickly, and it works best when started early after the loss occurs.