It’s been months since your ability to taste and smell disappeared after a Covid-19 infection. You’ve tried to schedule an appointment with a specialist — if you were able to find one — only to discover waiting lists of six months or longer.
“There was this explosion of patient calls after the pandemic started, and we couldn’t see 10% of the patients that wanted to come to the clinic,” said Dr. Justin Turner, associate professor of otolaryngology and head and neck surgery at Vanderbilt University Medical Center in Nashville, Tennessee.
Unfortunately, that’s still the case, leaving many who have yet to recover their sense of smell and taste struggling to find help, said rhinologist Dr. Zara Patel, who is a surgeon who focuses on treatment of the nose and sinuses.
“One of the big problems we realized at the beginning of the pandemic is that almost no one other than a few specialists knew anything about smell loss and how to go about diagnosing or treating it,” said Patel, a professor of otolaryngology and head and neck surgery at Stanford University School of Medicine in California.
Both Stanford and Vanderbilt have established clinics to treat and research smell loss, two of a handful in the United States.
“The sad and most common thing I hear from patients in my clinic who have seen multiple physicians before they get to me is that they were told: ‘There’s really nothing you can do. You’ll just have to see if your smell will come back with time,’” Patel said.
“When in reality, the sooner we start any definitive intervention, the more likely we are to be able to bring back smell.”
To address the issue, Patel said she gathered 50 experts to create a 600-plus-page consensus that combined vetted scientific knowledge and medical best practices on smell loss.
“It’s the first peer-reviewed compendium of its kind on olfaction,” Patel said. “And it’s open access — not just for physicians, but for patients, for anyone to read.”
The guidelines, published in the journal International Forum of Allergy & Rhinology, lay out a plan of action for general practitioners on how to examine, diagnose and treat smell loss — including when to make referrals to a specialist.
Patel encourages people with smell loss to print out the clinical assessment (see below) and take it to their doctor.
“We wrote this as a resource for patients to advocate for themselves — and for physicians who simply just don’t have the training or the expertise in this area,” Patel said. “They don’t just have to say, ‘Oh, there’s nothing that you can do.’ They can use this and learn about the different options for treatment.”
A trip to the doctor
The clinical assessment outlines a recommended order for the diagnosis of smell loss from any cause, not just Covid-19.
Patient history: A physician should take a detailed patient history, according to the guidelines. That will include questions about onset, severity and psychological impact of the loss of smell, along with possible culprits such as exposure to toxic chemicals, injuries or surgery to the head or nose, and radiation for cancer.
Headaches, chronic sinus issues, autoimmune disorders, some medications and vitamin or mineral deficiencies can be associated with smell loss as well as the common cold, flu and other viral illnesses such as Covid-19.
Age also can play a factor — all of us partially lose our sense of smell as more olfactory nerves fail to regenerate. People with Parkinson’s disease, Alzheimer’s disease and multiple sclerosis often have smell loss due to their illness’s impact on the brain.
Smell test: The doctor should administer a verified smell test. However, be aware some tests may not be sensitive enough to pick up subtle nuances in loss of smell, possibly leading a doctor to say nothing is wrong.
Some patients had that experience early in the pandemic when about 60% of people who had the Alpha and Delta variants complained of smell and taste loss, Turner said.
“When those patients started to be objectively tested, that positivity rate went way up — around 80% or even 90% of patients had some form of dysfunction if you really tested them,” Turner said.
It can also work in reverse, with many people unaware of nuances in smell recovery, said Dr. Eric Holbrook, an associate professor of otolaryngology and head and neck surgery at Harvard Medical School in Boston.
“There’s been papers showing that humans have difficulty assessing gradual change in their sense of smell,” Holbrook said. “Testing can differentiate a little bit, and it can be encouraging for some people to see that there has been a change.”
Physical workup: A full physical exam should be done, including a nasal endoscopy and an examination of cranial nerves. If the patient history shows evidence of a neurological disorder or chronic sinus inflammation, further testing should be ordered, the guidelines note.
If tests are positive, the patient should be referred to a specialist to treat that specific disorder. For example, a person with chronic sinusitis would be referred to a rhinologist.
If a specialist is needed, Patel suggested using the American Rhinologic Society’s website to find one in your area.
Potential treatments
The guidelines recommend various treatments, depending on the cause of the smell loss.
Underlying disorder: If the loss of smell is due to an underlying disease, such as chronic sinusitis or neurological condition, the guidelines suggest physicians refer the patient to a specialist and provide treatment options.
Surgery and trauma: If the loss is due to skull surgery, treatment with omega-3 fatty acids is recommended. If trauma such as a car accident is the cause, oral zinc and topical vitamin A are options.
“Using the term ‘options’ means that either there is very low level data that it may help,” Patel said, “or there are conflicting studies where some show it helps and some do not, but there is no data to suggest harm.”
Viral infections: If the smell loss is a result of a viral infection such as Covid-19 or the flu, a recommended treatment is smell training, a process in which patients practice smelling scents twice each day for at least six months.
“We start with four odors that are in different categories of smell so that they will stimulate different types of olfactory receptor neurons in your nose: lemon, rose, eucalyptus and clove,” Patel said.
Another recommendation is the use of steroids via a squeeze bottle nasal irrigation device similar to a neti pot, Patel said. Steroid nasal sprays don’t reach far enough up into the nose to reach the olfactory nerves.
“We add a topical steroid to the saltwater rinse and that allows you to bathe the neurons in the nose with a potent anti-inflammatory medication,” she said.
Safety studies on the use of steroids for chronic sinusitis patients have shown the body absorbs few steroids this way, she added: “So you don’t run into all those side effects that people get when they take steroids systemically by mouth or by injection.”
Other treatment options (not fully supported by research) for viral-induced smell loss may include topical vitamin A and omega-3 fatty oil supplements, the guidelines note.
The consensus also specifies which medications and treatments have little to no science supporting their use, such as systemic vitamin A, oral or nasal zinc, oral steroids or steroid nasal sprays, and platelet-rich plasma nasal injections.
When smells are nasty
People with smell loss can suddenly begin smelling vile odors: Food and drink smell rotten, decayed, metallic or chemically pungent. Doctors call the condition parosmia, caused when smell receptors fail to deliver accurate information to the brain. Distorted smell can occur after head trauma, neurological conditions or viral infections such as Covid-19.
“Parosmia is something that we have always seen with post-viral smell loss,” Patel said, “but not nearly to the same extent as we see it with Covid-19-related smell problems.”
The good news is that experts think parosmia is a sign of recovery. The guidelines consider smell training and certain medications as treatment options.
“Some people may respond to medications we call neuro-modulating agents — gabapentin, pregabalin, amitriptyline — medications that modulate the nerve signal back to the brain,” Patel said.
Emotional fallout
Finally, the guidelines state that your physician should discuss the emotional impact that a loss of smell can have and offer referrals to therapists or specialists as needed.
Some people manage fine without a sense of smell, Patel said. For others, it can lead to depression and malnutrition, especially if smell is distorted.
“Imagine you went to go eat and the food smelled and tasted like rotting flesh,” Patel said. “People end up with wild fluctuations where they lose a ton of weight, then they gain a ton of weight by finding some bland but highly fatty or starchy-type food that is safe for them.”
Groups such as Fifth Sense and the Smell and Taste Association of North America have mobilized to help, offering affirmation and hope, tips on smell training and even recipes to bolster appetite.
“A lot of our enjoyment of our environment is actually through our sense of smell,” Turner said. “Simple things like the smell of spring flowers, the smell of your child and your spouse or your significant other are ingrained in our minds.”
