Table 1.

Summary table of different drugs available for topical treatment for smell loss.

Treatment Method	Drug	Mechanism of Action	Clinical Application	Method of Application	References
Intranasal Corticosteroids	Anti-inflammatory agents	Reduces inflammation in the olfactory epithelium	Chronic rhinosinusitis	Sprays/aerosols Drops Irrigations	[2,23,24]
Intranasal Insulin	Hormone involved in glucose metabolism and cell growth	Stimulates olfactory stem cell proliferation and differentiation	Postviral olfactory dysfunction, general olfactory sensitivity	Sprays Gelfoam	[39,40]
Intranasal Theophylline	Phosphodiesterase inhibitor	Increases cyclic adenosine monophosphate and cyclic guanosine monophosphate levels in nasal secretions	General olfactory sensitivity	Irrigation sprays	[45,46]
Intranasal Tetra Sodium Pyrophosphate/Sodium Citrate	Calcium chelating agent	Lowers intranasal calcium concentration to improve olfactory signalling	Postviral olfactory dysfunction, general olfactory sensitivity	Drops Sprays	[28,47,50,51]
Intranasal Platelet-Rich Plasma	Contains growth factors important in tissue repair	Aids regeneration of damaged olfactory neuroepithelial cells or basal stem cells	Postviral olfactory dysfunction, general olfactory sensitivity	Injection	[56,57]
Vitamin A	Metabolite of vitamin A	Induces neuronal regeneration in the olfactory epithelium	Postviral olfactory dysfunction, general olfactory sensitivity	Drops	[58,59,60,61]
Omega-3	Polyunsaturated fatty acid	Enhances membrane fluidity and synaptic function	General olfactory sensitivity	Irrigation	[63,64,65]