Nonallergic rhinitis (NAR) is a frustrating condition where you experience symptoms like a runny nose and congestion, but you aren't actually allergic to anything. It's what doctors might call a "diagnosis of exclusion," meaning they'll confirm you have NAR only after all your allergy tests come back negative. This is the main difference from allergic rhinitis, which is an immune reaction to specific allergens like pollen or dander.
NAR is triggered by different things, most often environmental irritants like smoke, strong odors, or even just a sudden change in the weather. The symptoms are also different; while allergies famously cause intense itching in the nose and eyes, NAR is dominated by congestion and postnasal drip with minimal to no itching. It also tends to appear in adulthood, typically after age 20, whereas allergies often start in childhood.
The reasons "why" this happens are varied, as NAR isn't one single disease but a collection of subtypes. These causes generally fall into two main categories: inflammatory or non-inflammatory.
The inflammatory type (like NARES) involves inflammatory cells in the nasal lining, much like an allergy, but without any allergic trigger.
The more common non-inflammatory type is believed to be a nerve-related issue. In these cases, the autonomic nervous system in the nose is imbalanced and overactive. A specific nerve receptor, TRPV1, becomes hypersensitive. When a trigger like cold air or spicy food hits this receptor, it sends signals that cause vasodilation (congestion) and ramp up mucus production (runny nose). This nerve-driven mechanism explains subtypes like gustatory rhinitis (runny nose when you eat) and idiopathic rhinitis (triggered by irritants). Other subtypes can be caused by hormonal shifts (like during pregnancy) or even by certain medications, including the well-known "rebound congestion" from overusing decongestant sprays.
Since the causes are so different, treatment has to be matched to the specific subtype.
For the inflammatory types, studies suggest a combination spray containing both a nasal steroid and a nasal antihistamine is most effective.
For the non-inflammatory, nerve-driven types, the goal is to block those signals. An anticholinergic spray (like ipratropium) works very well to dry up a runny nose. A unique treatment is intranasal capsaicin, which uses the active compound from chili peppers to desensitize the overactive nerves, providing long-term relief.
For severe, stubborn cases of rhinorrhea, there are even surgical procedures that can ablate or disrupt the nerves responsible for the symptoms.
Wirach Chitsuthipakorn, MD