The current study will be a pilot study for a randomized controlled trial conducted on patients recruited from the outpatient clinic of the Otorhinolaryngology Department, Menoufia Faculty of Medicine To evaluate the effect of vitamin D nasal drops in the treatment of post COVID 19 parosmia

The current study will be a pilot study for a randomized controlled trial conducted on 60 patients recruited from the outpatient clinic of the Otorhinolaryngology Department, Menoufia Faculty of Medicine after approval of the institutional review board and taking informed written consent from every patient before participation in the study.

To be included in the study, patients should be more than 18 years old, have a history of COVID 19 infection more than three months ago as confirmed by PCR test, have a post COVID parosmia, and have no history of systemic steroid administration over the last one month. History of previous nasal surgery, underlying systemic diseases (like diabetes mellitus, hypertension, or autoimmune diseases), and hypersensitivity to Ivermectin were the exclusion criteria for this study.

Patients of the study will be randomly and equally distributed between case and control groups using block randomization methods using 4 blocks each comprising 4 patients with 6 patterns for every block one of which was selected randomly using random numbers generated by Excel program. The case group will receive a 4 week course using Devarol S amp containing 200,000 units per 2 ml giving a concentration of 5,000 units per drop. The patients will receive two drops per nostril twice daily. The Control group will receive a 4 weeks course of local steroids in the form of budesonide (64 µg per puff in a dose of 1 puff for each nostril twice daily.

Assessment protocol:

Patients of the study will be assessed before and at the end of the treatment protocol with history taking to define the inclusion and exclusion criteria. Endoscopic examination of the nasal cavity will be performed to exclude any other intranasal pathology. The degree of parosmia will be assessed using a visual analog scale before and four weeks after treatment.

Outcome measures:

Primary outcome measures will include a comparison between the pre and post treatment values of visual analog scales of parosmia, and a comparison between case and control groups regarding the post treatment results whether no improvement, partial improvement, or complete improvement. Secondary outcome measures will include assessment of the side effects of Ivermectin nasal drops among the case group.

nclusion Criteria:

• Patients should be more than 18 years old,
• Patients having a history of COVID 19 infection more than three months ago as confirmed by PCR test,
• Patients having a post COVID parosmia,
• Patients having no history of systemic steroid administration over the last one month.

Exclusion Criteria:

• History of previous nasal surgery,
• Underlying systemic diseases (like diabetes mellitus, hypertension, or autoimmune diseases),
• Hypersensitivity to vitamin D3.

Study data will be available on request from the authors

After publication of the study results

On approval of the authors of the study

The statistician will be blinded to the patient's group