A stuffy nose that never really clears, a dull pain around the eyes that returns every morning: when these discomforts last for months, we are no longer talking about just a simple cold. Chronic sinusitis is an inflammation of the sinuses that persists beyond twelve weeks, even with treatment. Understanding what sustains it and knowing how long it can last changes the way we approach the issue with our doctor.
Post-viral chronic sinusitis: a rapidly growing cause
Online medical content often presents the same triggers: allergy, deviated septum, nasal polyps. These factors are indeed real. However, since 2023, ENT teams have reported an increase in cases of chronic rhinosinusitis that appeared after a viral infection, particularly following Covid-19.
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The mechanism is quite simple to visualize. A respiratory virus causes inflammation of the mucous membrane lining the sinuses. Normally, this inflammation decreases within a few weeks. In some individuals, the mucous membrane remains swollen well beyond the infectious phase. Mucus does not drain properly, the sinuses remain blocked, and the symptoms (nasal obstruction, facial pain, loss of smell) persist for more than three months.
To better understand the causes and duration of chronic sinusitis, it is essential to consider the patient’s recent infectious history, not just their allergic background.
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This post-viral form affects individuals who sometimes had no particular ENT history. Their common point: a respiratory infection (Covid-19 or another virus) followed by inflammation that refuses to resolve. Specialists refer to prolonged hyposmia, meaning a lasting decrease in smell, as a frequent marker of these cases.
Sinus inflammation: the mechanisms that sustain chronicity
Have you ever noticed that a cold heals in a week for some and lingers for weeks for others? The difference often lies in how the mucous membrane reacts to the initial assault.
The vicious circle of mucus-mucosa
The sinuses are air-filled cavities carved into the bones of the face. They communicate with the nasal passages through narrow openings. When the mucous membrane that lines them swells, these openings become blocked. Mucus accumulates, pressure changes, and inflammation sustains itself even without active infection.
This vicious circle distinguishes chronic sinusitis from a typical acute sinusitis. The initial infection (viral or bacterial) may have disappeared long ago, but inflammation persists because the natural drainage of the sinuses is no longer functioning.
Factors that hinder healing
Several elements can prevent the mucous membrane from returning to its normal state:
- An untreated allergy (dust mites, pollen, mold) that maintains a permanent inflammatory state in the nasal passages, even outside of visible flare-ups.
- Nasal polyps, which are benign growths of the mucous membrane that mechanically obstruct the openings of the sinuses and prevent mucus from draining.
- A deviated septum or an anatomical anomaly that reduces the size of the passages between the sinuses and nasal cavities.
- A general inflammatory background, sometimes linked to hormonal imbalances or sensitivity to non-steroidal anti-inflammatory drugs (aspirin, ibuprofen), what ENT specialists refer to as Widal’s triad.
In most cases, chronic sinusitis results from the combination of two or three of these factors, not just one.
Duration of chronic sinusitis: what twelve weeks really means
The twelve-week threshold is not arbitrary. It is the duration beyond which doctors consider that the inflammation is no longer just a simple extension of an acute infection, but an autonomous problem that requires different management.
In practical terms, chronic sinusitis can last for months or even years if it is not properly identified. Some individuals live with diminished symptoms that they attribute to repeated colds, while it is actually a single ongoing inflammation.
Chronic sinusitis is also discussed when acute episodes recur more than four times a year. In this case, the mucous membrane never has the chance to recover completely between two flare-ups.
Biotherapies and severe chronic sinusitis with nasal polyps
When intranasal corticosteroids and surgery are not sufficient to control chronic sinusitis with polyps, a new therapeutic option exists. Biotherapies targeting eosinophilic inflammation represent a shift in approach for severe forms.
Mepolizumab (marketed under the name Nucala) is now indicated as a maintenance treatment for adults with severe chronic rhinosinusitis with nasal polyps inadequately controlled by intranasal corticosteroids. The French product monograph describes a significant reduction in exacerbations and the need for oral corticosteroids.
To understand the benefit of these treatments, it is important to know that nasal polyps are often associated with eosinophilic-type inflammation. Eosinophils are white blood cells that, in excess, sustain the swelling of the mucous membrane. Biotherapies act directly on this mechanism, where corticosteroids have a broader and less targeted effect.
This option does not apply to all patients. It is aimed at resistant forms, after failure of standard treatments. The decision lies with a specialized ENT, often in conjunction with an allergist.
When to consult an ENT for persistent sinusitis
A general practitioner treats the majority of acute sinusitis cases. Consulting an ENT becomes relevant in specific situations:
- Nasal symptoms (obstruction, discharge, facial pain) that last beyond three months despite proper treatment.
- A loss of smell that does not return after a respiratory infection.
- Episodes of acute sinusitis that recur several times a year.
- A sinus scan showing thickening of the mucous membrane or polyps.
The ENT has tools that the general practitioner does not have: nasal endoscopy (a small camera inserted into the nose) and sinus scans, which allow for precise visualization of the state of the mucous membrane and the permeability of the drainage openings.
Chronic sinusitis is not a fatality, but it also does not resolve with nasal sprays used without follow-up. Identifying the exact cause of the inflammation, whether allergic, anatomical, post-viral, or mixed, remains the condition for adapting treatment and shortening the duration of symptoms.