bubble_chart Overview

Allergic rhinitis is a disease caused by inhaling external allergic antigens, characterized by symptoms such as nasal itching, sneezing, and clear nasal discharge. Due to the seasonal increase or decrease or persistent presence of allergens, the onset of this disease can be seasonal (commonly known as hay fever) or perennial. Like patients with inhalant asthma, they often have a clear genetic allergic constitution (atopy). During disease episodes, itching may also occur in the conjunctiva, palate, and external ear canal.

bubble_chart Etiology

This disease arises from two fundamental factors: ① a hereditary allergic constitution; ② repeated exposure to and inhalation of external allergens.

Most patients with allergic rhinitis possess an allergic constitution, meaning they tend to produce more IgE in response to external antigens compared to normal individuals. This constitution has a certain degree of heredity and familial tendency, making it more likely for these patients to concurrently or sequentially suffer from eczema, dermatitis, drug allergies, and bronchial asthma. Such allergic diseases are also more prevalent within the families of these patients.

The inhaled antigens that trigger this disease include dust mites, house dust, animal dander, and wind-pollinated particles from various trees and grasses, such as Mongolian snakegourd root. Most of these antigen particles are relatively large (5–25 μm), allowing them to be trapped in the nasal cavity, where they induce a type I hypersensitivity reaction. This leads to a series of symptoms, including nasal mucosal congestion, edema, and increased secretions. The immunological process involved is similar to that of inhaled bronchial asthma.

bubble_chart Pathological Changes

During the onset of the disease, the nasal mucosa is significantly swollen with extremely active mucus secretion. Microscopic examination reveals a marked increase in the number of goblet cells, obvious edema of the epithelium and basement membrane, and extensive infiltration of eosinophils. Some patients may exhibit similar pathological changes in the conjunctiva, posterior pharyngeal wall, and other areas. These pathological alterations significantly diminish or even disappear during the remission stage.

bubble_chart Clinical Manifestations

During the onset of the disease, nasal itching, continuous sneezing, and a profuse watery nasal discharge are the clinical features, sometimes accompanied by intense itching in the conjunctiva, the palate, and even the external auditory canal. Due to swelling of the nasal mucosa, patients often experience stuffy nose and hyposmia. Symptoms typically worsen in the morning and evening but improve during the day and after physical activity. Patients usually show no obvious systemic symptoms, but complications such as sinusitis may lead to fever, facial distending pain, lack of strength, and poor appetite.

Most patients develop the disease in childhood, with a distinct seasonal pattern, and the onset period is closely related to the fluctuation of specific allergens in the surrounding environment. In most temperate regions, the disease is most likely to occur in spring and autumn.

After contracting the disease, patients often develop a hypersensitive state of the nasal mucosa. During the onset season, any strong odors, polluted air, or even changes in climate and temperature can trigger symptom recurrence. In the late stage [third stage], patients may develop allergies to multiple antigens and stimuli, leading to a year-round tendency toward stuffy nose and nasal discharge.

During the stage of attack, patients often exhibit a characteristic open-mouth breathing appearance (especially noticeable in children). Frequent rubbing of the nose due to itching may result in transverse creases on the nasal bridge and hypertrophy of the nasal wings. Those with allergic conjunctivitis may also show grade I conjunctival congestion and edema. Rhinoscopy reveals pale, edematous nasal mucosa with copious watery secretions, and microscopic examination often shows a high number of eosinophils.

In laboratory tests, patients often exhibit a positive immediate-type reaction to corresponding antigen skin tests (the reaction usually occurs within 10–15 minutes). In vitro tests such as the radioallergosorbent test (RAST) or enzyme-linked immunosorbent assay (ELISA) can also detect the presence of specific IgE in the patient's serum.

Only 30–40% of patients show elevated total IgE levels, and eosinophil counts in the blood may be slightly elevated or remain normal.

bubble_chart Diagnosis

The diagnosis of this disease should include: ① whether it is allergic rhinitis; ② what the possible allergens are.

Stuffy nose and runny nose are extremely common clinical symptoms, so the following conditions must be excluded in the differential diagnosis:

(1) Deviated nasal septum or turbinate hypertrophy — The patient's stuffy nose often persists year-round, is mostly unilateral, and lacks nasal itching or obvious seasonal发作 tendencies. Nasal endoscopy can confirm the diagnosis.

(2) Drug-induced rhinitis (rhinitis medicamentosa) — Common medications that can cause stuffy nose and increased secretions include rifampin and its various preparations, ganglion blockers, oral contraceptives, etc. In recent years, due to excessive use of vasoconstrictors (e.g., naphazoline) or overly strong effects for stuffy nose, drug-induced rhinitis can also frequently occur due to the rebound vasodilation effect, requiring careful differentiation.

(3) Symptomatic stuffy nose — Apart from the clinically common common cold, easily overlooked conditions include premenstrual stuffy nose in women, stuffy nose during pregnancy, and stuffy nose due to hypothyroidism.

(4) Vasomotor rhinitis — This is a type of "episodic" rhinitis of unknown cause. The patient's nasal symptoms often occur suddenly due to temperature changes, consumption of spicy food, or inhalation of irritating odors, making it easily confused with this disease. The key distinguishing features are the absence of sneezing, nasal itching, or sore throat symptoms, and the ineffectiveness of antihistamines and desensitization therapy.

(5) Chronic rhinitis — Also known as eosinophilic perennial nonallergic rhinitis, its nasal secretions also contain large numbers of eosinophils, with symptoms often persisting year-round. However, allergens are often undetectable, so the disease cause remains unclear. Such rhinitis patients are prone to accompanying nasal polyps, and some may also have infection-type asthma (thus forming the "aspirin allergy-asthma-rhinitis nasal polyp triad"). The differences from allergic rhinitis are obvious nasal congestion and turbinate swelling, mucus-like secretions, poor response to antihistamines, and ineffectiveness of sodium cromoglycate and desensitization therapy.

Through careful history-taking, possible types of allergens in patients with this condition may be identified. Then, skin tests can be performed using extracts of these suspected antigens. If all results are negative, the disease can be ruled out. However, positive results do not necessarily confirm the diagnosis. A concentrated antigen solution is instilled into one nostril, while physiological saline is instilled into the other as a control. If symptoms such as nasal itching, runny nose, or sneezing occur within 15 minutes after instilling the antigen, it indicates a positive reaction, suggesting that the instilled antigen may be the patient's specific allergen.

bubble_chart Treatment Measures

The treatment principles for this disease are: ① Avoid inhaling allergens that can trigger reactions; ② Use appropriate medications; ③ Undergo drug or antigen desensitization therapy.

(1) Avoid inhalation of antigens. For example, those allergic to Mongolian snakegourd root should avoid gardens or wilderness during the onset season; those allergic to house dust should wear masks when sweeping; those allergic to dust mites should use a vacuum cleaner for bed cleaning. Families with the means can use air purifiers in bedrooms during the onset season and keep windows and doors closed.

(2) Symptomatic drug treatment. Patients in the stage of attack should take oral antihistamine H₁ receptor drugs, commonly including Atarax, promethazine, and chlorpheniramine. These also have certain sedative and anticholinergic effects. To reduce nasal mucosal swelling and blockage during an attack, sympathomimetic α-receptor agonists are often applied locally to constrict blood vessels. The most commonly used are 1% ephedrine or 0.5% furacilin ephedrine, administered 1–4 times daily, 2–4 drops each time.

(3) Desensitization measures. Since the essence of this disease is a type I hypersensitivity reaction manifested in the nose, the following desensitization measures for type I reactions can be considered as appropriate:

1. Disodium cromoglycate. It protects mast cells on the nasal mucosal surface from degranulation, achieving preventive and therapeutic effects. A freshly prepared 4% solution can be used as nasal drops, 4 times daily, 5–10 drops each time.

2. Ketotifen (Zaditen). It has antihistamine H₁ receptor effects and antiallergic properties. Taken orally twice daily, 1 mg each time. Children over 6 years old can use the adult dose. The antihistamine effect appears quickly, but the antiallergic effect often becomes noticeable only after 2–3 weeks of use. Therefore, it is advisable to start taking it before the stage of attack or continue for at least one month for better results. In recent years, many European and American scholars have increasingly questioned the above effects of ketotifen.

3. Corticosteroids. Oral prednisone at 10–20 mg daily can control most symptoms, but due to its side effects, it is only suitable for a few severe cases. Locally applied beclomethasone aerosol, 3–4 times daily, 150 μg per inhalation (3 sprays), is often effective for most patients without systemic hormonal side effects. Before applying topical steroids or disodium cromoglycate, if the patient has severe stuffy nose, it is advisable to first use 1% ephedrine nasal drops to constrict blood vessels, ensuring the medication reaches deep into the nasal cavity.

4. Chinese medicinals. "Qing Gan Bao Nao Wan" can be taken orally three times daily, 10 g each time. Alternatively, small centipeda herb (Centipeda minima L.) can be ground into fine powder and mixed with Vaseline to form a 10% ointment for nasal application, 2–3 times daily, which also has preventive effects.

5. Antigen desensitization therapy. Similar to inhalant asthma, this therapy can be tried for patients with identified inhalant allergens or those who also have asthma.