Allergic Rhinitis: Causes, Diagnosis, Treatment and Prevention
Allergic rhinitis is IgE-mediated inflammation of the nasal mucosa after exposure to an allergen. It commonly causes sneezing, nasal itching, watery rhinorrhoea and obstruction, and may occur with allergic conjunctivitis, asthma or eczema.
Itching + sneezing + clear rhinorrhoea + variable nasal obstruction strongly suggests allergic rhinitis, especially when symptoms follow a recognisable exposure.
Learning objectives
- Classify allergic rhinitis by pattern and severity.
- Explain the immediate and late allergic responses.
- Recognise typical symptoms, signs and important alternatives.
- Outline allergen avoidance, drug treatment and referral indications.
Common allergens and risk factors
Grass, tree and weed pollens often produce seasonal symptoms.
Persistent exposure occurs in bedding, mattresses and soft furnishings.
Proteins from skin, saliva and urine may trigger symptoms.
Fungal spores, flour, wood dust and laboratory animals are examples.
Atopy, family history of allergic disease and coexisting asthma or eczema increase susceptibility. Tobacco smoke, pollution, strong odours and temperature changes may aggravate symptoms without being the primary allergen.
Pathophysiology
- Initial exposure promotes allergen-specific IgE production.
- IgE binds mast cells in the nasal mucosa.
- Re-exposure cross-links IgE and releases histamine and other mediators.
- The immediate response produces itching, sneezing and watery secretion.
- A late inflammatory response involving eosinophils causes persistent congestion and hyper-reactivity.
Understanding the anatomy of the nose helps explain how mucosal swelling obstructs airflow and sinus drainage.
Classification
| Dimension | Definition |
|---|---|
| Intermittent | Symptoms occur on fewer than 4 days per week or for fewer than 4 consecutive weeks. |
| Persistent | Symptoms occur on at least 4 days per week and for at least 4 consecutive weeks. |
| Mild | No troublesome symptoms, sleep disturbance or impairment of daily activities. |
| Moderate–severe | Sleep, school, work or daily activities are affected, or symptoms are troublesome. |
Clinical features
- Paroxysmal sneezing and nasal itching.
- Clear, watery rhinorrhoea and post-nasal drip.
- Alternating or bilateral nasal obstruction.
- Itchy, red or watery eyes.
- Reduced smell, cough, throat clearing, fatigue or poor sleep.
Examination
The mucosa may be pale, oedematous and bluish with clear secretions. Look for mouth breathing, an allergic salute, a transverse nasal crease, conjunctivitis, eczema, wheeze, sinus tenderness and nasal polyps. A unilateral mass, blood-stained discharge or persistent unilateral obstruction is not a typical simple allergy presentation.
Diagnosis and investigations
Diagnosis is usually clinical: establish the symptom pattern, triggers, home and occupational exposures, medicine use, effect on sleep and presence of asthma. Apply a structured ENT physical examination.
- Skin-prick testing or serum allergen-specific IgE can confirm sensitisation when the result will change management.
- A positive allergy test must match the clinical history; sensitisation alone does not prove that an allergen causes symptoms.
- Nasal endoscopy may be indicated for severe, unilateral, atypical or treatment-resistant disease.
- CT is not routine for uncomplicated allergic rhinitis; consider it when chronic sinus disease or another structural problem is suspected.
Review allergen testing in ENT and ENT investigations.
Differential diagnosis
| Condition | Clues |
|---|---|
| Viral rhinitis | Short duration, malaise, sore throat and thicker discharge. |
| Non-allergic rhinitis | Congestion and rhinorrhoea without itching, sensitisation or clear allergen pattern. |
| Rhinitis medicamentosa | Rebound obstruction after prolonged topical decongestant use. |
| Sinusitis | Facial pain or pressure, purulent discharge and reduced smell. |
| Foreign body | Unilateral offensive discharge, especially in a child. |
| Mass or tumour | Progressive unilateral obstruction, epistaxis, facial swelling or cranial signs. |
Management
Education and exposure reduction
- Identify clinically relevant triggers and reduce exposure where practical.
- Use saline nasal irrigation with safe water and clean equipment.
- Avoid tobacco smoke and irritants that worsen symptoms.
- Teach correct spray direction: away from the septum, toward the lateral wall, with gentle inspiration.
Medicines
| Option | Best use and cautions |
|---|---|
| Intranasal corticosteroid | Most effective single treatment for regular moderate–severe symptoms, especially obstruction. Benefit depends on daily use and correct technique. |
| Second-generation antihistamine | Useful for itching, sneezing and rhinorrhoea; non-sedating agents are preferred when available. |
| Intranasal antihistamine | Rapid relief; may be used alone or combined with an intranasal steroid. |
| Eye drops | Antihistamine or mast-cell stabiliser drops may help ocular symptoms. |
| Decongestant | Topical agents should be short term only because prolonged use causes rebound congestion; consider cardiovascular cautions. |
| Leukotriene antagonist | Not usually first-line; may be considered in selected patients with coexisting asthma after risks and benefits are reviewed. |
Allergen immunotherapy may be offered by specialists for proven, clinically important allergy that remains troublesome despite appropriate measures. Check asthma control because rhinitis treatment can improve overall airway health.
Referral and red flags
Refer urgently for unilateral bleeding or mass, visual symptoms, facial swelling, severe headache, neurological signs or suspected anaphylaxis. Routine specialist review is appropriate when diagnosis is uncertain, symptoms remain severe despite adherence, occupational disease is suspected, or immunotherapy is being considered.
Key examination points
- Allergic rhinitis is an IgE-mediated inflammatory disease, not simply “a cold.”
- Itching, sneezing and clear rhinorrhoea are characteristic.
- Diagnosis is usually clinical; allergy tests confirm sensitisation only when interpreted with the history.
- Intranasal corticosteroids are the strongest single therapy for persistent or obstructive symptoms.
- Technique, adherence, trigger reduction and asthma assessment are essential.
References and further reading
- NHS: Allergic rhinitis.
- NHS: Antihistamines.
- MSD Manual Professional: Nasal congestion and rhinorrhoea.
For education only. Apply findings together with current Uganda Clinical Guidelines, local protocols and specialist advice.
