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Doctors Feel Hopeful About Restoring Taste and Smell Loss After COVID

The second phase of a clinical trial for patients to regain their sense of taste and smell is about to begin, and it is showing promising results.

Otolaryngologist Dr. David Rosen has been helping patients restore their sense of taste and smell after respiratory infections for two decades. When the COVID-19 pandemic hit, a concerning number of people were experiencing this overwhelming side effect. Traditional therapy to treat this condition can require a painful injection directly up the nostril to the olfactory nerve. But, Dr. Rosen began trying a less invasive treatment using a topical application of platelet-rich plasma (PRP) into the nose to stimulate cell regrowth and restore taste and smell. This therapeutic approach, which shows some success, is now entering into phase II clinical trial. Nancy, a patient suffering from persistent anosmia after a COVID diagnosis in 2021, shared how this trial has helped her senses begin to return.

We spoke with Dr. Rosen and otolaryngologists, Drs. Glen D’Souza and Alexander Duffy, about how the clinical trial is helping patients.

How is COVID causing loss of taste and smell?

Rosen: COVID is directly binding to the lining of the nose through a particular receptor called the ACE-2 receptor. The nose lining gets damaged, along with the cells it supports called the olfactory cells, commonly known as the smell cells. Because they lose the supporting cells, the olfactory cells can’t function properly.

How does treatment to regain taste and smell begin?

Rosen: First, we prescribe an oral steroid, work with patients through olfactory training (smell training), and suggest they begin taking supplements, such as V vitamin A, alpha-lipoic acid, sodium citrate, or omega 3. They can also use an over-the-counter nasal steroid. If they don’t recover within six months, we start trying more aggressive treatments, such as the one used in our clinical trial.

Can you tell us more about the treatment offered in the clinical trial?

Rosen: We are taking a patient’s blood and spinning it down to remove the red cells and saving the plasma, which has all the platelets in it. We take the PRP, and we apply that topically into the nose. This helps the cells regenerate because PRP can help cell regeneration throughout the body, for example, hair regrowth.

How many sessions have patients needed before they make any improvement?

Rosen: Phase II of the trial will help us better determine the number of appointments most patients need but based on the data we have, a minimum of three treatments are needed.

Is there a sign that shows people are beginning to recover?

Rosen: Most signs are subjective. Some patients can have phantosmia (smelling odors that aren’t there) or parosmia (when smell and taste are distorted). For example, one patient said that chicken tasted incredibly awful. It only took one session for their taste to go back to normal.

Duffy: Our patients share anecdotal evidence. As their senses return, they’ll notice they’re able to smell something in their house, or they’ll be able to smell something sweet. Some patients begin to have signs of parosmia, which may seem like a bad sign, but it is a positive indicator of smell recovery.

What have been the most common complaints from those with smell/taste loss?

Rosen: Everything tastes like cardboard. I had one patient with terrible phantosmia saying everything smelled like burnt cigarettes. Most people come in with more taste complaints than smell complaints because it is more noticeable when you cannot taste.

D’Souza: One patient said that everything smelled like rust. Another shared that every time she smelled onions or garlic, she felt like she was going to vomit.

Duffy: The psychological impact is something patients often mention. Anosmia is associated with anxiety and depression. Patients may become socially recluse as their hygiene may be affected. They can face weight loss or gain as they begin to eat for texture more than taste. Those experiencing anosmia are also at an increased risk of eating expired food and are more likely to experience a hazardous event in the home (i.e., smoke or natural gas leak).

What about parosmia? Will the clinical trial help? Are there recommendations for those experiencing this?

Rosen: If someone has been having signs of parosmia (distorted smell) and loss of smell for over six months, they can join the PRP clinical trial. The trial wasn’t developed to treat this per se, but we have had success with having a single session helping a patient’s parosmia. Parosmia is a sign that your olfactory nerve is working, and the PRP can push this out to have proper odor identification. Even without the PRP study, a patient experiencing this should see a doctor, and an oral steroid may help, along with smell exercises. [Editor’s Note: to learn more about the experience behind the clinical trial, read Nancy’s story here.]

What should be the first step someone takes when their anosmia is not going away?

Rosen: Smell exercises. Start smell exercises right away. An over-the-counter nasal steroid may help. Smell exercises have the best evidence of smell retraining. [Editor’s Note: For details on how to perform smell exercises, read our interview with Dr. Rosen]

Duffy: I agree. You can schedule an appointment with an otolaryngologist to help guide you with smell training. Patients should also make sure that smoke detectors work in their homes and have a carbon monoxide detector.

How can patients continue to see improvement with anosmia/parosmia at home?

Rosen: Assess the things that you have at home for smell training. Start smelling objective odors available to you, coffee, oranges, or perfumes around your home. Start with four scents and then work towards more as some return. If you begin to smell citrus, acknowledge that as progress and start smelling another scent.

How are you feeling going into phase II of the clinical trial?

Rosen: It’s early to say, but this clinical trial is showing good promise. This has been the largest PRP clinical trial for anosmia, and in the first phase, we are seeing a 30-35% improvement for patients. It gives me a lot of hope.


[Main photo credit: ©Thomas Jefferson University Photography Services]

[Editor’s Note: to see if you’re eligible to enroll in the clinical trial, fill out this form.]

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