Chronic Sinusitis With Nasal Polyps (CRSwNP): Causes, Symptoms, and Evidence-Based Treatment

Chronic sinusitis with nasal polyps (CRSwNP) is a distinct and particularly challenging form of chronic rhinosinusitis, affecting approximately 1-4% of the general population and accounting for roughly 20-30% of all chronic sinusitis cases. Unlike chronic sinusitis without polyps, CRSwNP is driven predominantly by Type 2 inflammation — an immune response pattern characterised by eosinophilic infiltration, elevated IgE, and persistent tissue remodelling that leads to the formation of benign but obstructive polyp growths within the nasal cavity and paranasal sinuses. Nasodren®, a Class IIA medical device (CE 0051) derived from 100% natural Cyclamen europaeum extract, is indicated to relieve symptoms of acute and chronic rhinosinusitis by promoting natural sinus drainage — including in patients with nasal polyps.

This comprehensive guide covers the definition, pathophysiology, clinical presentation, diagnostic approach, and full spectrum of evidence-based treatments for CRSwNP, from intranasal corticosteroids to biologics and surgery, as well as the role of natural supportive therapies in long-term management.

What Is Chronic Sinusitis With Nasal Polyps (CRSwNP)?

Chronic rhinosinusitis (CRS) is defined as symptomatic inflammation of the nasal cavity and paranasal sinuses lasting 12 weeks or longer, with at least two of four cardinal symptoms: nasal blockage or congestion, rhinorrhoea (anterior or posterior nasal discharge), facial pain or pressure, and reduction or loss of smell. When this chronic inflammation leads to the formation of bilateral nasal polyps — semi-translucent, oedematous growths arising from the sinus mucosa, typically originating in the ethmoid sinuses — the condition is classified as chronic sinusitis with nasal polyps (CRSwNP).

Nasal polyps are benign growths of the sinus lining. They are not tumours and carry no risk of malignant transformation. However, their progressive enlargement can obstruct the nasal airway, impair olfactory function, block sinus drainage, and serve as a reservoir for chronic infection. Histologically, polyps consist of loose connective tissue, oedema, inflammatory cells — predominantly eosinophils in Western populations — and glandular structures embedded within a damaged epithelial surface.

The diagnosis of CRSwNP requires endoscopic confirmation of bilateral polyps. Unilateral polyps warrant further investigation to exclude inverted papilloma or malignancy. CRSwNP is distinguished from chronic sinusitis without nasal polyps (CRSsNP) by its distinct inflammatory profile, greater symptom severity, higher rate of asthma comorbidity, and greater tendency toward recurrence after treatment.

How Common Is CRSwNP?

Global prevalence of CRSwNP is estimated at 1-4% of the general population, with a peak age of diagnosis between 40 and 60 years. Men are more frequently affected, accounting for approximately 60-65% of diagnosed cases, although emerging data suggest that women may experience more severe disease manifestations.

CRSwNP represents approximately 20-30% of all chronic rhinosinusitis cases, but this proportion varies significantly by geography. In Western populations, the eosinophilic, Type 2-driven endotype predominates. In Asian populations, neutrophilic inflammation is more common, reflecting different underlying immunological profiles and treatment responses.

The economic burden is substantial. Patients with CRSwNP have significantly higher healthcare utilisation — including more specialist visits, imaging studies, and surgical procedures — compared to those with CRSsNP. The impact on quality of life, as measured by validated instruments such as the SNOT-22 (Sino-Nasal Outcome Test), rivals or exceeds that of chronic obstructive pulmonary disease (COPD), diabetes, and chronic heart failure.

How Do Nasal Polyps Form? The Pathophysiology of CRSwNP

The hallmark of CRSwNP is a dominant Type 2 inflammatory response, which distinguishes it from CRSsNP at the molecular and cellular level.

Type 2 inflammation is an immune cascade involving eosinophils, mast cells, basophils, and type 2 innate lymphoid cells (ILC2s). It is driven by three key cytokines: interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13). In the sinus mucosa of CRSwNP patients, this inflammatory cascade produces:

• Eosinophilic infiltration: Large numbers of eosinophils accumulate in polyp tissue, releasing cytotoxic proteins — including major basic protein and eosinophil cationic protein — that damage the respiratory epithelium and perpetuate inflammation.
• Elevated immunoglobulin E (IgE): Local and systemic IgE production is upregulated, contributing to allergic sensitisation and further immune activation within the sinonasal mucosa.
• Oedema and tissue remodelling: Chronic cytokine signalling promotes fluid accumulation, stromal oedema, fibrin deposition, and structural changes in the sinus lining that physically manifest as polyp growth.
• Epithelial barrier dysfunction: The mucosal barrier becomes compromised through reduced expression of tight junction proteins, increasing susceptibility to environmental triggers, microbial colonisation, and allergen penetration.

Approximately 80-85% of CRSwNP cases in Western populations demonstrate eosinophilic, Type 2-dominant inflammation. This endotype is clinically significant because it predicts both disease severity and treatment response — patients with Type 2 CRSwNP tend to have more extensive polyp burden, higher recurrence rates after surgery, and stronger comorbidity with asthma and aspirin-exacerbated respiratory disease (AERD).

In contrast, non-Type 2 CRSwNP — more prevalent in Asian populations — is characterised by neutrophilic inflammation and a different cytokine profile, requiring alternative treatment strategies. Understanding the inflammatory endotype is increasingly important as it guides the selection of biologic therapies.

What Are the Symptoms of CRSwNP?

The clinical presentation of chronic sinusitis with nasal polyps is marked by chronic, progressive symptoms that substantially impair daily functioning. Symptoms tend to be more severe and treatment-resistant compared to CRS without polyps.

1. Nasal Obstruction: The most prevalent and bothersome symptom. Polyp tissue physically blocks the nasal airway, producing bilateral congestion that progressively worsens. Patients frequently report a sensation of complete nasal blockage.
2. Hyposmia or Anosmia (Loss of Smell): Loss of smell is a cardinal and often distinguishing feature of CRSwNP. It is typically more severe than in CRSsNP and is frequently irreversible without surgical intervention. The impact extends beyond quality of life — patients lose the ability to detect smoke, gas leaks, or spoiled food, creating genuine safety concerns.
3. Rhinorrhoea and Postnasal Drip: Persistent mucus production, often thick and mucopurulent, drains anteriorly from the nose and posteriorly into the throat, causing chronic cough, throat clearing, and irritation.
4. Facial Pressure and Pain: Dull, aching pressure over the cheeks, forehead, or between the eyes, typically exacerbated by bending forward. The pain is less acute than in acute bacterial sinusitis but more persistent.
5. Sleep Disturbance and Fatigue: Nasal obstruction forces mouth breathing during sleep, contributing to snoring, frequent awakenings, and poor sleep quality. Chronic fatigue is a common but under-recognised symptom.
6. Reduced Quality of Life: Studies consistently demonstrate that CRSwNP patients experience quality-of-life impairment comparable to or exceeding that of COPD, diabetes, or congestive heart failure. The SNOT-22 questionnaire captures this multidimensional impact across physical, functional, and emotional domains.

The CRSwNP–Asthma Connection: Unified Airway Disease

One of the most clinically important features of CRSwNP is its strong association with asthma. Approximately 60% of CRSwNP patients have comorbid asthma (PMC 2023: 59.63%), a rate far exceeding what would be expected by chance. This relationship reflects the concept of unified airway disease, in which the upper and lower airways share a common inflammatory pathology — when one is inflamed, the other frequently follows.

The CRSwNP–asthma connection is further amplified in patients with aspirin-exacerbated respiratory disease (AERD), also known as Samter’s triad, which combines:

1. Chronic sinusitis with nasal polyps
2. Asthma
3. Respiratory reactions to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs)

AERD affects approximately 7-15% of adult asthma patients and up to 30-40% of CRSwNP patients. These individuals typically have more severe, recalcitrant disease with higher polyp recurrence rates and greater dependence on systemic corticosteroids. Comprehensive management of CRSwNP therefore requires assessment and coordinated treatment of comorbid lower airway disease.

Causes and Risk Factors for CRSwNP

The precise aetiology of CRSwNP remains incompletely understood, but evidence supports a multifactorial model involving the following contributors:

1. Type 2 Inflammatory Predisposition: The strongest identified risk factor. Genetic and environmental influences drive a predisposition toward eosinophilic, Type 2-skewed immune responses.
2. Epithelial Barrier Dysfunction: Defects in the sinonasal epithelial barrier — whether genetic (as in cystic fibrosis) or acquired (through chronic inflammation or environmental damage) — allow allergens, microbes, and irritants to penetrate the mucosa and trigger sustained immune activation.
3. Allergic Rhinitis: While not all CRSwNP patients are atopic, uncontrolled allergic rhinitis can perpetuate mucosal inflammation and contribute to polyp growth.
4. Asthma and AERD: As discussed, these conditions share immunopathogenic mechanisms with CRSwNP and amplify disease severity.
5. Microbial Colonisation and Biofilm: Staphylococcus aureus colonisation and biofilm formation are common in CRSwNP. Bacterial biofilms — structured communities encased in a protective extracellular matrix — resist antibiotic penetration and host immune clearance, contributing to persistent inflammation.
6. Anatomical Factors: Structural variations such as septal deviation, concha bullosa, or a narrow ostiomeatal complex can impair sinus ventilation and drainage, creating conditions favourable for polyp formation.
7. Environmental Exposures: Tobacco smoke, occupational dusts, and air pollution can damage the respiratory epithelium and trigger or exacerbate inflammation.

How Is CRSwNP Diagnosed?

Accurate diagnosis integrates clinical assessment, nasal endoscopy, and imaging.

Clinical History: Documentation of symptom duration (≥12 weeks), character, severity, impact on quality of life, prior treatments, and comorbid conditions — particularly asthma and aspirin sensitivity.

Nasal Endoscopy: The gold standard for diagnosis. Direct visualisation of the nasal cavity using a rigid or flexible endoscope allows identification of polyps — typically appearing as pale, glistening, grape-like masses originating from the middle meatus — as well as assessment of mucosal oedema, discharge character, and anatomical abnormalities. Bilateral polyp visualisation confirms CRSwNP. Unilateral polyps require biopsy to exclude neoplasia.

Computed Tomography (CT): CT of the paranasal sinuses provides detailed assessment of disease extent, sinus opacification, ostiomeatal complex patency, and anatomical variants. The Lund-Mackay scoring system (0-24) objectively quantifies disease severity. CT is indicated when medical therapy fails, when surgery is being considered, or when complications are suspected. The diagnostic sensitivity of CT exceeds 90%.

Additional Testing: Allergy testing (skin prick or specific IgE), assessment of olfactory function, and in selected cases, evaluation for cystic fibrosis, primary ciliary dyskinesia, or immunodeficiency.

CRSwNP Treatment: A Stepwise Approach

Treatment of CRSwNP follows a stepwise algorithm guided by disease severity, treatment response, and the presence of comorbid conditions. The EPOS2020 and EUFOREA guidelines provide evidence-based frameworks for therapeutic escalation.

Step 1: Intranasal Corticosteroids (INCS)

Intranasal corticosteroids are the foundation of CRSwNP treatment. Regular, long-term use reduces polyp size, improves nasal airflow, restores olfactory function, and decreases the frequency of acute exacerbations. The effect is local — systemic absorption is minimal. Clinical response should be assessed after 8-12 weeks of consistent use.

Step 2: Nasal Irrigation

High-volume (>200 mL) saline irrigation — isotonic or slightly hypertonic — mechanically clears mucus, allergens, and inflammatory mediators from the sinonasal cavity. When used in conjunction with INCS, irrigation enhances drug delivery to the sinus mucosa. EPOS2020 assigns saline irrigation a Level 1a evidence grade.

Step 3: Systemic Corticosteroids

For patients with moderate-to-severe polyposis who do not respond adequately to topical therapy, a short course of oral corticosteroids (typically prednisolone 0.5-1 mg/kg/day for 5-10 days) can rapidly reduce polyp size and improve symptoms. However, the effect is temporary, and repeated courses carry cumulative risks including adrenal suppression, bone density loss, hyperglycaemia, and weight gain. Systemic corticosteroids should be used sparingly and as a bridge to more definitive therapy.

Step 4: Antibiotics (Selected Cases)

Antibiotics are reserved for acute bacterial exacerbations superimposed on CRSwNP — characterised by purulent discharge, increased facial pain, and fever. Doxycycline, in addition to its antimicrobial activity, has demonstrated anti-inflammatory effects in CRSwNP. However, routine or prolonged antibiotic use is not recommended due to limited efficacy against biofilm-embedded bacteria and concerns about antimicrobial resistance.

Step 5: Biologic Therapy

For patients with severe, uncontrolled Type 2 CRSwNP who have failed medical and surgical therapy, biologic agents represent a transformative advance. Dupilumab (Dupixent®), a monoclonal antibody targeting the IL-4 receptor alpha subunit (IL-4Rα), blocks both IL-4 and IL-13 signalling — the central drivers of Type 2 inflammation. Clinical trials have demonstrated significant reductions in polyp size, improvements in nasal airflow and smell, and decreased need for systemic corticosteroids and revision surgery.

Other biologics under investigation or in clinical use for CRSwNP include omalizumab (anti-IgE), mepolizumab (anti-IL-5), and benralizumab (anti-IL-5Rα). Biologic therapy requires careful patient selection, typically reserved for those with bilateral polyps who have undergone prior sinus surgery and remain symptomatic despite maximum medical therapy.

Step 6: Endoscopic Sinus Surgery (FESS)

Functional Endoscopic Sinus Surgery (FESS) is indicated when maximal medical therapy — including adequate trials of INCS, irrigation, and systemic corticosteroids — fails to control symptoms. FESS aims to restore sinus ventilation and drainage by removing polyps, opening obstructed sinus ostia, and preserving as much healthy mucosa as possible.

FESS produces significant symptomatic improvement in the majority of appropriately selected patients. However, CRSwNP has a tendency toward polyp recurrence — rates of revision surgery range from 15-20% within 5 years, and patients with Type 2 inflammation, asthma, or AERD have higher recurrence rates. Meticulous postoperative care — including continued INCS use and regular saline irrigation — is essential for maintaining surgical outcomes.

Natural Treatment Options: Nasodren® for CRSwNP

Nasodren® is a Class IIA medical device (CE 0051) formulated from the lyophilised extract of fresh Cyclamen europaeum tubers. It is a 100% natural nasal spray, free from excipients and preservatives, indicated to relieve symptoms of both acute and chronic rhinosinusitis.

The mechanism of action is distinct from pharmacological treatments. Upon application, the saponins in cyclamen extract stimulate trigeminal nerve endings in the nasal mucosa, triggering a secretomotor reflex that produces profuse serous secretion from the sinus cavities. This reflexive fluid mobilisation clears retained mucus, reduces mucosal oedema, and restores natural sinus drainage — without systemic absorption or rebound congestion.

Clinical Evidence: Cyclamen europaeum extract received a Level A recommendation in EPOS 2012 (evidence level Ib) — the highest grade assigned in the most authoritative international guideline for rhinosinusitis management. Nasodren® has been evaluated in over 30 published clinical studies across multiple countries, with results published in leading peer-reviewed journals including Rhinology (the official journal of the European Rhinologic Society) and The Laryngoscope (the official journal of the American Rhinologic Society). Clinical data demonstrate that in 90% of cases, normal nasal and sinus function is restored by day 7 of treatment.

It should be noted that a Cochrane systematic review (Chong et al., 2018) assessed the evidence for cyclamen extract as insufficient to confirm efficacy, highlighting the need for further research whilst acknowledging its inclusion in EPOS guidelines.

Safety in CRSwNP: Nasodren® is safe for use in patients with nasal polyps. Its non-pharmacological, physiologic mechanism carries no systemic side effects and no drug interactions, making it a valuable addition alongside intranasal corticosteroids and as part of post-surgical maintenance. It is administered once daily and works within minutes of application. The product is not absorbed systemically and does not reach the bloodstream.

CRSwNP vs CRSsNP: Key Differences

Complications of Untreated CRSwNP

When CRSwNP remains inadequately treated, progressive polyp growth and chronic inflammation can lead to:

1. Complete Anosmia: Permanent loss of smell with associated safety risks and reduced quality of life.
2. Recurrent Acute Exacerbations: Superimposed bacterial infections requiring repeated antibiotic courses.
3. Orbital Complications: Infection extending through the lamina papyracea into the orbit, causing preseptal or orbital cellulitis.
4. Asthma Deterioration: Uncontrolled upper airway inflammation destabilising lower airway disease.
5. Obstructive Sleep Apnoea: Chronic nasal obstruction contributing to sleep-disordered breathing.
6. Musculoskeletal Effects of Repeated Steroid Use: Osteoporosis, myopathy, and adrenal insufficiency from recurrent oral corticosteroid courses.
7. Intracranial Extension (Rare): Meningitis, epidural abscess, or brain abscess — medical emergencies requiring immediate intervention.

Quality of Life Impact

The burden of CRSwNP extends far beyond sinonasal symptoms. SNOT-22 scores in CRSwNP patients consistently demonstrate impairment across all domains:

• Physical: Constant nasal obstruction, facial pressure, sleep disruption, and fatigue.
• Functional: Reduced work productivity, difficulty with physical activity, and limitation of daily activities.
• Emotional: Embarrassment, frustration, depression, and anxiety related to chronic symptoms and visible effects of the disease.

Successful treatment — whether medical, surgical, or combined — should aim not only to reduce polyp size and improve endoscopic scores but to measurably improve quality of life as assessed by validated patient-reported outcome measures.

Long-Term Management Strategy

CRSwNP is a chronic condition requiring sustained, long-term management. The goal is not cure but control — maintaining symptom relief, preserving olfactory function, preventing exacerbations, and minimising disease progression and the need for repeated interventions.

An effective long-term strategy includes:

1. Daily INCS — the cornerstone of maintenance therapy, continued indefinitely.
2. Regular Saline Irrigation — to maintain mucociliary clearance and reduce inflammatory load.
3. Allergen and Trigger Avoidance — for patients with identified allergic or environmental triggers.
4. Nasodren® as maintenance or rescue therapy to promote sinus drainage and prevent mucus stasis.
5. Regular Specialist Follow-Up — endoscopic monitoring to detect early polyp recurrence.
6. Prompt Treatment of Exacerbations — to prevent acute episodes from accelerating disease progression.

With consistent application of these principles, the majority of CRSwNP patients can achieve sustained symptom control and maintain a good quality of life.

Frequently Asked Questions About Chronic Sinusitis With Nasal Polyps

What is the difference between CRSwNP and ordinary chronic sinusitis?

CRSwNP involves the presence of bilateral nasal polyps — benign growths arising from inflamed sinus mucosa. The condition is driven predominantly by Type 2 inflammation, produces more severe smell loss, has higher asthma comorbidity (~60%), and is more likely to require surgery than chronic sinusitis without polyps (CRSsNP).

Can nasal polyps become cancerous?

Nasal polyps are benign and carry no risk of malignant transformation. However, unilateral polyps — those appearing on only one side — warrant thorough investigation including biopsy to exclude inverted papilloma or malignancy. Bilateral polyps characteristic of CRSwNP are not precancerous.

How effective is FESS surgery for CRSwNP?

FESS produces significant symptomatic improvement in the majority of appropriately selected patients who have not responded to maximal medical therapy. However, polyp recurrence is common, with approximately 15-20% of patients requiring revision surgery within five years. Postoperative INCS and saline irrigation are essential for prolonging surgical benefit.

What role do biologics play in CRSwNP treatment?

Biologics such as dupilumab target the specific immune pathways driving Type 2 inflammation in CRSwNP. They are reserved for patients with severe, uncontrolled disease who have failed both medical therapy and surgery. Biologics can significantly reduce polyp size, improve symptoms, and decrease the need for systemic corticosteroids and revision surgery.

Is Nasodren® safe for patients with nasal polyps?

Yes. Nasodren® is a Class IIA medical device (CE 0051) made from 100% natural Cyclamen europaeum extract. It is safe for use in patients with nasal polyps and can be used alongside intranasal corticosteroids. It works through a non-pharmacological mechanism — stimulating natural sinus drainage — without systemic absorption or drug interactions.

Can CRSwNP be cured permanently?

CRSwNP is a chronic inflammatory condition. While it cannot be permanently cured in most cases, it can be effectively controlled through consistent medical therapy (INCS, irrigation), appropriate surgical intervention when indicated, and long-term maintenance strategies. The goal of treatment is sustained symptom control and preservation of quality of life.

What is aspirin-exacerbated respiratory disease (AERD)?

AERD, also known as Samter’s triad, is a condition combining CRSwNP, asthma, and respiratory reactions to aspirin or NSAIDs. It affects up to 30-40% of CRSwNP patients and is associated with more severe, treatment-resistant disease and higher polyp recurrence rates. These patients should avoid aspirin and NSAIDs unless under specialist supervision.

How often should CRSwNP patients be followed up?

After diagnosis and initiation of treatment, follow-up is typically at 3-6 month intervals. Endoscopic examination allows assessment of treatment response and early detection of polyp recurrence. Patients on biologic therapy or those with severe disease may require more frequent monitoring.