COVID-19 May Cause Parosmia. What Is It?

Woman smelling an orange.

Dmitry Marchenko / EyeEm

Key Takeaways

  • Some people recovering from COVID-19 report that foods taste rotten, metallic, or skunk-like, describing a condition called parosmia.
  • COVID-19 can damage olfactory receptors in the nose or the parts of the brain necessary for smelling.
  • There’s no way of knowing when a person’s sense of smell will return to normal, but smell training may help.

Losing the sense of taste and smell is commonly associated with COVID-19. However, it’s not the only smell dysfunction that people might experience. People recovering from COVID-19 are also reporting that the smell of rotting meat seems to follow them everywhere. Normal odors may even suddenly smell rotten, metallic, or skunk-like.

These individuals describe a condition called parosmia where odors become distorted. A 2021 study found that almost half of the survey participants who had parosmia and a confirmed case of COVID-19 recovered their sense of smell in about three months.

For some people, the condition lasts much longer than that. A young woman recently went viral on TikTok for talking about her ongoing experience with parosmia, which started around ten months ago.

According to experts, parosmia may occur if COVID-19 damages olfactory receptors in the nose or affects the parts of the brain necessary for the sense of smell.

How Does Parosmia Occur?

To understand olfactory or smell disorders, it’s crucial to be aware of how the sense of smell works first.

“Odors are created by chemicals or ‘aromatic compounds’ that float through the air and stimulate chemical receptors in the nose,” Andrew Schamess, MD, internal medicine physician at The Ohio State University Wexner Medical Center, told Verywell. “Anything that has an odor has a unique chemical signature that a person perceives as a smell.”

To smell properly, an individual has to be able to perceive the smell through the chemical receptors in their nose. Their brain then needs to process that input to create an olfactory image, he added. Therefore, parosmia can occur when:

  • Only some of the nose’s chemical receptors are working, so an individual picks up parts of the chemical signature, which results in a distorted smell
  • The sensors in the nose are working, but the brain is unable to process the sensory input, like when there is nerve damage in the olfactory pathway

Having a distorted sense of smell, or parosmia, can turn normal, everyday odors—not just food—into exceedingly unpleasant ones.

“Parosmia is a change in the normal perception of odors, usually taking pleasant smells and turning them into foul ones,” R. Peter Manes, MD, FACS, Yale Medicine rhinologist and associate professor of surgery at the Yale School of Medicine, told Verywell. “It can be caused by infections, seizures, even brain tumors.”

Why Does COVID-19 Affect the Sense of Smell?

“COVID-19 has been linked with a loss of smell and taste,” Manes said. “Patients can either instead develop parosmia, or note parosmia as they are recovering from their loss of smell.”

Anosmia, the partial or full loss of sense of smell, is a common symptom of COVID-19. While it’s different from parosmia, the two are related. There is still much to know about COVID-19 and how the disease affects the body, but it’s possible that the virus damages the olfactory receptors in the nose, causing anosmia and parosmia.

“COVID-19 also affects the brain,” Schamess said. “It damages the supporting cells for nerves, and thus interferes with nervous system functioning. That’s why some patients after COVID-19 infection have fatigue, brain fog, etc. When the damage occurs in the parts of the brain that are necessary for smell, it results in absence or distortion of the sense of smell.”

How Can It Impact Daily Life?

Smell disorders like parosmia and anosmia significantly affect patients’ quality of life, experts say.

“Our sense of smell is a vital sense,” Manes said. “It helps protect us from danger, including smoke from a fire and spoiled food. It also provides patients with great pleasure. We link smell to meals, shared time with friends, and wonderful memories.”

To avoid any dangers, monitor food expiration dates and ensure that smoke and natural gas detectors are functioning properly.

“Patients with anosmia and parosmia can lose interest in food,” Schamess said. “I have seen a few become dangerously underweight. For others, problems with smell can rob them of the pleasure of cooking and eating. They can feel disconnected from others. Food preparation and eating can be an important part of parenting, socializing, and ethnic identity.”

People with parosmia might also struggle with personal hygiene, pet care, home care, and other aspects where olfactory clues play a crucial role. However, for people who lost their sense of smell in relation to COVID-19, parosmia may be a sign of gradual recovery.

“Interestingly, parosmia can be a sign of a recovering sense of smell,” Schamess said. “As smell receptors in the nose come back online, recovery of individual receptor types is uneven. Affected patients can perceive some of the chemicals that comprise odors, but not others, leading to distorted odor perception. Going from no smell to distorted smell can be a step on the road to recovery.”

When Does Your Smell Return to Normal?

“There is no way to say when it will go away,” Manes said. “Most patients with smell dysfunction after COVID-19 infection return to normal, but there is so little known about long-term effects that it is unclear how many patients will return to normal.”

Having a distorted sense of smell can affect one’s daily function, so many try to get their sense of smell back to normal through a relatively simple and cheap method called smell training.

It is usually done by picking three to four scents and breathing them in deeply for five to ten minutes a couple of times a day, Schamess said. Strong smells like cloves, citrus, coffee, and lavender are usually recommended. Individuals can also change the chosen scents every week.

Olfactory retraining can be effective in helping “jump-start” the olfactory recovery, he added. People can put together a scent kit using foods, herbs, soaps, scented candles, essential oils, and other items with a strong scent that are available at home.

However, further research on the effectiveness of smell training is needed before making any definitive conclusions, Manes said. There are some case studies that looked at the efficacy of smell training for olfactory dysfunction, but it’s difficult to make a concrete deduction since most people normally recover their sense of smell over time.

“The majority of patients have recovered normal smell and taste within three months,” Schamess said. “For some, smell and taste disorders last longer. I have seen patients still affected after a year.”

“Eventually, the rest of the smell receptors recover, and smell perception returns gradually to normal,” he added. “This is true in many patients, although, unfortunately, not all.”

What This Means For You

Smell disorders can last for weeks or months, but smell perception eventually returns to normal for most people who had COVID-19. You can try smell training to potentially aid your recovery.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Villar PMAC, Chua RU, Robles RP. Smell training in prolonged COVID-19 post-infectious olfactory dysfunction: a case report. Philipp J Otolaryngol Head Neck Surg. 2021;36(1):37-40. doi:10.32412/pjohns.v36i1.1655

By Carla Delgado
Carla M. Delgado is a health and culture writer based in the Philippines.