Have you noticed that familiar things suddenly smell unpleasant? It could be parosmia, a disorder in which the odors of certain things -- or, in some cases, everything -- are distorted.
This happens when smell receptor cells in your nose, called olfactory sensory neurons, don’t detect odors and translate them to your brain the way they should. Usually, the smell is bad or even revolting. For example, if you sniff a banana, instead of something fruity and pleasant, your nose may pick up a foul odor like rotting flesh. Parosmia is common after a viral infection.
Several things may cause parosmia. They can include:
- Upper respiratory infections like colds
- Head injury
- Sinus infections
- Certain toxins and drugs
- Seizures in part of the brain called the temporal lobe
- Brain tumors
- Constant dry mouth
COVID-19 and Parosmia
A total loss of smell and taste are hallmark symptoms of COVID-19. One study says it happens to at least 25% of people who catch SARS-CoV-2, the coronavirus that causes COVID-19. Some reports have also linked COVID-19 infections to parosmia.
Most people with a complete loss of smell (called anosmia) from COVID-19 find that their senses go back to normal over time. But problems can linger in a few people, or they may have an altered sense of taste and smell for weeks or months after the infection.
Nearly half of people with COVID-19 who took part in one study reported parosmia about 2.5 months after their initial infection, and it continued for at least 6 months. According to some, the “COVID smell” was “foul,” “rancid,” or similar to “rotting flesh.”
Another international study found that 7% of people reported a distorted sense of smell after COVID-19 infection. But experts say they need more information and larger studies to better understand how the illness may affect smell and taste.
Your senses play a big role in your everyday life. Good smells can often lift your mood and bring joy. On the flip side, a distorted sense of smell can have a big effect on your quality of life. It can lead to problems like:
- Loss of appetite
- Weight loss
When your sense of smell isn’t reliable, you may be at risk of missing things like spoiled food, smoke, or a gas leak. If your sense of smell is important for your work, like chefs, perfumers, and firefighters, parosmia may make it hard to do your job.
Parosmia Diagnosis and Treatment
If you think you may have parosmia, talk to your doctor. There’s no standard test for the condition. You might use Sniffin' Sticks to check how well you detect everyday smells to see if your olfactory system, the organs behind your sense of smell, are working as they should.
Your doctor will also do a physical exam and ask about your medical history to check for serious underlying problems like brain tumors.
They may try to rule out a similar condition called phantosmia. Unlike parosmia, in which your nose is still able to smell something, phantosmia is when your smell receptors “hallucinate” and detect odors that aren’t there. The smells may range from good to unpleasant. Phantosmia isn’t constant; it can come and go.
Your doctor might also recommend that you see a specialist to rule out nerve damage or head injuries. This can include:
- Otolaryngologists, who specialize in ear, nose, and throat conditions
- Neurologists, who focus on conditions related to the brain and nervous system
- Allergists, who handle allergies and related issues
Your doctor could prescribe medication to treat parosmia. Studies have found that these drugs may ease symptoms:
- Clonazepam (Klonopin)
- Phenytoin (Dilantin, Phenytek, Phenytoin Infatabs)
- Topiramate (Qudexy XR, Topamax, Trokendi XR)
- Valproic acid
If the drugs don’t work, you might have surgery to remove the damaged sensory receptors (olfactory mucosa) in your nasal cavity. But because it’s a complex procedure with major risks, doctors recommend surgery only if necessary.
There’s no treatment for parosmia that happens because of a viral infection like COVID-19 or a head injury. Damaged nerves in your nose and nasal cavity can grow back, so your sense of smell may partially or fully return without treatment.