This study evaluates whether adding topical insulin to intranasal platelet-rich plasma (PRP) improves smell recovery in adults with post-inflammatory anosmia. Participants will be randomly assigned to receive either intranasal PRP combined with topical insulin or intranasal PRP alone. Changes in olfactory function will be assessed over time to compare the effectiveness and safety of the two treatments.

Post-inflammatory anosmia is a common cause of persistent olfactory dysfunction with limited effective treatment options. Platelet-rich plasma (PRP) has been proposed as a regenerative therapy due to its high concentration of growth factors, while topical insulin has demonstrated potential neurotrophic and anti-inflammatory effects in olfactory tissue.

This randomized controlled trial aims to evaluate whether the addition of topical insulin to intranasal PRP provides greater improvement in olfactory function compared with intranasal PRP alone in adults with post-inflammatory anosmia. Participants will be randomly assigned to receive either combined intranasal PRP plus topical insulin or intranasal PRP alone.

Olfactory function will be assessed at baseline and at predefined follow-up time points using validated smell testing methods. Safety and tolerability of the interventions will also be monitored throughout the study. The results of this study will contribute to understanding the potential role of regenerative and neurotrophic therapies in the management of post-inflammatory anosmia

Inclusion Criteria:

• Diagnosed with olfactory dysfunction despite olfactory training therapy
• Loss of smell within the past 5 years
• Loss of smell occurred after an infection
• Platelet count is over 150,000 platelets per microliter

Exclusion Criteria:

Have a history of or currently have sinonasal tumours Have a history of surgery or radiotherapy for the base of your skull Have been treated with antibiotics in the past month before surgery Have a condition called systemic vasculitis or any bleeding disorder Have a suspected or known allergy to insulin or PRP or Platelet Lysate (PL) Have inhaled drugs (i.e cocaine) in the past 6 months of your enrollment Smell loss is due to a head trauma or after surgery Unable to complete the Sniffin Stick Smell test or questionnaires