PRP Treatment Injects Hope for People Suffering From Smell Loss

By Stephanie Feuer

There are glasses for people with vision challenges, aids for the hearing impaired, and all manner of medications for infections. But for people who suffer from acquired smell loss, clinicians have had little to offer.

Smell training has been shown to be beneficial for many. Steroids, Dupixent, alpha-lipoic acid, vitamin A drops , Omega-3, insulin, Gabapentin and zinc have been been deployed with varying degrees of effectiveness, but millions of people worldwide suffer from prolonged smell loss. An estimated nine million people in the U.S. alone still have olfactory impairments as a result of Covid-19.

 Now there is a whiff of hope. A lasting treatment for smell loss may be in the patient’s own blood. Clinicians are reporting success restoring the sense of smell to individuals with acquired smell loss using platelet-rich plasma (PRP), a therapy that has been successfully used to treat carpal tunnel syndrome, sports injuries, joint pain, wounds and hair loss.

New Study Reports Long Term Results

A study recently published in the International Forum of Allergy & Rhinology found that people who received the PRP treatment were 12.5 times more likely to have improved olfactory function compared to patients who received placebo injections.

Zara Patel, MD, Director of Endoscopic Skull Base Surgery and a Professor of Otolaryngology at Stanford Medicine and her team followed a group of  26 patients who had persistent smell loss lasting between six and 12 months and had documented prior Covid-19 infections. They had also tried other treatments such as olfactory training and steroid rinses. Half of the participants received three injections of platelet-rich plasma into their nasal cavity over a period of six weeks, while the other half received placebo injections of saline on the same schedule.  

Results Seen at Three Months and One Year

Three months after their initial treatment, the people in the PRP group scored 6.25 points higher on an objective smell test compared to their pretreatment scores, with the most improvement in the area of odor discrimination. The placebo group also showed improvement, scoring an average of 3.67 points higher than they had before the study. At three months, 57.1% of the platelet-rich plasma group had shown a clinically significant improvement, compared with just 8.3% in the placebo group.

Notably, these improvements lasted. After one year 87.5% of those who received PRP injections showed significant improvement in their smell test scores, compared to just 31.2% in the non-PRP group.

What is PRP and How is it Used to Treat Smell Loss?

Platelet-rich plasma is a concentrated solution of an individual’s own blood. Blood is drawn from the patient and then it is centrifuged to separate the platelets from other blood components. 

In a video report about the procedure, Zara Patel shares, “one of the great things about PRP is that you're not having to inject any outside synthetic material, no other type of medication that could have side effects or adverse events. PRP is rich in growth factors. It helps tissue regenerate throughout our body.”

While the PRP is prepared, the patient’s nose is anesthetized. Then the PRP is injected into the olfactory cleft on one or both sides. The procedure is repeated three times, two weeks apart.

Patel has created a video for patients and providers describing this procedure in detail. 

Are there Other Studies of PRP as a Treatment for Smell Loss?

• PRP was tested as a treatment for smell loss even before Covid. A small pilot study in 2018 was a proof of concept that demonstrated PRP could lead to improved olfactory perception.

• In 2022, Carol Yan, MD, and team conducted a randomized control clinical trial of PRP for smell loss from Covid. They found that there was improvement in smell discrimination following PRP treatment, but no difference in smell identification or threshold.

• Dr. David Rosen of Jefferson Health conducted a clinical trial in 2022 of a topical platelet-rich plasma treatment with some patients reporting improvement in their post-Covid smell loss.

• In 2023, Sage Journal published a study by Taiwanese clinicians who evaluated 28 patients who received PRP injections. They found that three months after the treatment, 85 % reported their olfactory function improved.

• In Belgium Dr. Jerome Lechien of  EpiCURA Hospital, University of Mons conducted a trial and has now treated some 400 patients with PRP. He reports that 81% of patients treated with PRP noticed an improvement in their sense of smell over a period of time between three weeks and six months.

• The Journal of Clinical Medicine published a review of the literature of 10 PRP studies which totaled 531 patients, ranging in age from 15 to 63. Six of these studies used PRP for post-Covid smell loss, one for smell loss after functional endoscopic sinus surgery, and three on post-infectious or post-traumatic smell loss. They concluded that PRP, “may be a risk-free and efficient therapeutic option with very encouraging outcomes. Indeed, it enhances olfactory perception in patients who not only exhibit COVID-19 infection aftereffects, but also in those who have lost their sense of smell due to trauma, rhinosinusitis, rhinitis, or even surgery.”

Will it Work For Me?

FifthSense, the UK-based patient support group issued a statement reminding people that PRP is still considered experimental in the UK and that more research needs to be done. 

Zara Patel is committed to continuing to gather data about the effectiveness of PRP. She says “While PRP does not help every patient, the majority of those I have injected have experienced improvement. There is significant variability in how much each patient benefits—some gain only slight improvements, while others experience dramatic recoveries. I am continuing to collect data to determine if there are predictive factors that can help counsel patients on whether this intervention is likely to work for them.”

Claire Hopkins, a former president of the British Rhinological Society and professor of Rhinology at King’s College London issued a statement on PRP. She said, “ the availability of PRP as a treatment option is something that should be celebrated by those who aim to support patients with loss of sense of smell….certainly the published studies highlight that PRP will not help all patients with post-viral smell loss, and further studies are required before we can make recommendations for use in patients with smell loss from other causes.”

With more clinicians worldwide now offering PRP treatments for smell loss, we should soon learn much more about the effectiveness and best practices of PRP treatments for smell loss. That’s a whiff of hope for those experiencing the life-changing impact of acquired smell loss.