August 03, 2023

Smell Loss (Anosmia) Treatment Involving Platelet-Rich Plasma Injections Show Great Promise

 Research out of Stanford have suggested that injections of platelet-rich plasma derived from the patient's own blood may significantly restore sense of smell even for those patients who have suffered smell loss for a long period of time. These injections are performed into the top part of the nasal cavity where the smell nerve endings are located.

In the original pilot study published in 2020, ALL study participants reported a subjective improvement of their smell shortly after injection which then stabilized, though most did not achieve normal smell sense. Most of the improvement occurred within the first 4 weeks.

Platelet-rich plasma (PRP) is created as described by the GS30‐PURE II Protocol A (Emcyte, Ft Myers, Florida):

This protocol isolates PRP products with high platelet, low granulocyte count, and minimal red blood cells. Briefly, 20 mL of patient's whole blood was drawn and added to 5 mL of sodium citrate (SC) anticoagulant. The blood was centrifuged at 4200 rpm for 1 minute upon which the platelet plasma suspension supernatant was aspirated and re‐centrifuged at 4200 rpm for 5 minutes. The subsequent supernatant or the platelet poor plasma was discarded until 2 mL of PRP remained.

The PRP is drawn up into a 1ml syringe and injected into the nasal mucosa containing the smell nerve endings in 2 separate locations in divided doses. This is then repeated in the opposite side.

Follow up studies (see below) confirm these findings and suggest that repeated injections every month for 3 months provide even greater benefit.

At this time, these injections are considered experimental and as such, are not covered by insurance. However, with time, it is hoped that the veracity of these results become convincing enough such that insurance will start to cover these injections.

Also keep in mind that this research has been limited to those who have lost their sense of smell within the past 12 months. Unclear whether those who have lost smell sense for years would benefit from this treatment.

For those who have suffered smell loss and are desperate for treatment, lack of insurance coverage has not stopped many patients for self-paying for these PRP injections. Based on a 2023 Standford news article, Dr. Zara Patel, the researcher who developed the PRP protocol for smell loss, runs a clinic that is now 6 months backlogged with patients interested in these injections.

My clinic is not offering this treatment at this time. Standard treatment for smell loss include steroids, theophylline nasal spray, and smell therapy.


The use of platelet‐rich plasma in treatment of olfactory dysfunction: A pilot study. Laryngoscope Investig Otolaryngol. 2020 Apr; 5(2): 187–193. Published online 2020 Feb 21. doi: 10.1002/lio2.357

Use of platelet-rich plasma for COVID-19-related olfactory loss: a randomized controlled trial. Int Forum Allergy Rhinol. 2023 Jun;13(6):989-997. doi: 10.1002/alr.23116. Epub 2022 Dec 21.

Platelet-rich plasma injection in the olfactory clefts of COVID-19 patients with long-term olfactory dysfunction. Eur Arch Otorhinolaryngol. 2023 May;280(5):2351-2358. doi: 10.1007/s00405-022-07788-8. Epub 2022 Dec 15.

Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids.

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