Imagine waking up one morning after recovering from Covid-19 to find that your coffee smells like unwashed socks, your eggs reek of feces and your orange juice tastes metallic. Oddly, that’s a good thing: It’s a sign you still have a working sense of smell – even if it’s miswired in your brain.
Your ability to smell can also disappear completely, a condition called anosmia. Without warning, you can no longer inhale the sweet odor of your baby’s skin, the roses gifted by your partner or the pungent stink of your exercise clothes.
Taste and smell are intertwined, so food may be bland or flavorless. Appetite and enjoyment of life may plummet, which past studies show can lead to nutritional deficits, cognitive decline and depression.
Danger lurks as well. Without smell, you may not recognize the telltale signs of fires, natural gas leaks, poisonous chemicals or spoiled food and drink.
Such is the reality of some 5% of global Covid-19 survivors who have now developed long-lasting taste and smell problems, according to a 2022 study. More than two years into the pandemic, researchers found an estimated 15 million people may still have problems perceiving odors, while 12 million may struggle with taste.
Smell or olfactory training encourages people to sniff essential oils twice a day, said rhinologist Dr. Zara Patel, a professor of otolaryngology, head and neck surgery at Stanford University School of Medicine.
“The way I explain it to patients is if you had a stroke, and it made your arm not work, you would go to physical therapy, you would do rehab,” Patel said. “That’s exactly what olfactory training is for your sense of smell.”
As science learns more about how Covid-19 attacks and disrupts smell, “I think you’re going to see interventions that are more targeted,” said rhinologist Dr. Justin Turner, an associate professor of otolaryngology, head and neck surgery at Vanderbilt University Medical Center in Nashville.
Anyone still struggling with a loss of smell and taste “should think positively and assume their sense of smell will return,” Turner said. “Yes, there are some people that won’t recover, so for those folks, we want them to not ignore it. We want them to take it seriously.”
Cases exploded due to Covid-19
People have been losing their sense of smell and taste for centuries. Common cold and flu viruses, nasal polyps, thyroid disorders, severe allergies, sinus infections and neurological conditions such as Alzheimer’s disease, Parkinson’s disease and multiple sclerosis can all damage the ability to smell and taste – at times, permanently.
So can head trauma, exposure to noxious chemicals, cancer treatments, smoking, gum disease, antibiotics and various blood pressure, cholesterol, reflux and allergy medications, according to the Cleveland Clinic.
Growing old is a major cause of smell loss as the ability of the olfactory neurons to regenerate declines. A study conducted in 1984 found more than 50% of people between ages 65 and 80 years suffered from “major olfactory impairment.” The number climbed to more than 75% for people over age 80.
When the virus that causes Covid-19 invaded our lives, a condition that was relatively rare among people under 50 expanded exponentially, affecting all ages.
“Covid-19 affected younger people much more than other forms of post-viral smell loss,” said surgeon Dr. Eric Holbrook, an associate professor of otolaryngology and head and neck surgery at Harvard Medical School. “You wouldn’t see much smell loss in the pediatric population, for example, and now it’s very common.”