The pathophysiology of rhinitis medicamentosa (rebound congestion from prolonged use of topical decongestants) is best explained by:

• A Down-regulation of alpha-2 adrenergic receptors on mucosal blood vessels leading to rebound vasodilation when the drug is withdrawn, combined with secondary oedema from local tissue hypoxia ✓
• B IgE-mediated mast cell degranulation triggered by the decongestant vehicle
• C Parasympathetic receptor up-regulation causing excessive cholinergic tone after drug withdrawal
• D Eosinophilic inflammation triggered by preservatives in nasal sprays

Explanation

Rhinitis medicamentosa occurs after prolonged use (>5–10 days) of topical alpha-adrenergic decongestants (oxymetazoline, xylometazoline). The proposed mechanisms include: (1) down-regulation (tachyphylaxis) of nasal mucosal alpha-2 adrenoreceptors, reducing vasoconstriction between doses; (2) rebound vasodilation (reactive hyperaemia) as drug effect wanes; (3) ischaemic mucosal damage from prolonged vasoconstriction leading to secondary oedema; and (4) possibly reduced endogenous norepinephrine release. Treatment requires gradual cessation of the topical decongestant, substitution of topical corticosteroids, and systemic decongestants if needed during weaning.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.