Allergic rhinitis (hay fever)
An allergic reaction in the nose to airborne triggers such as pollen, dust mites or pet dander, causing sneezing, a runny or blocked nose and itchy eyes. Extremely common, it is usually diagnosed from the story rather than blood tests.
What it is
Allergic rhinitis is inflammation of the lining of the nose caused by an allergic (IgE-mediated) reaction to inhaled allergens. When a sensitised person breathes in the trigger, the immune system releases histamine and other chemicals, producing sneezing, itching, a runny or blocked nose, and often itchy, watery eyes (allergic conjunctivitis). It is called hay fever when triggered seasonally by pollens (grass, tree, weed), and is perennial (year-round) when driven by indoor allergens such as house dust mite, pet dander or mould. It is one of the most common conditions worldwide, often runs in families, and clusters with asthma and eczema (the 'atopic' triad). While generally not dangerous, it can significantly affect sleep, concentration and quality of life, and poorly controlled rhinitis can worsen asthma. The diagnosis is usually clinical; testing identifies the specific trigger when that will change management.
Key lab markers
- Diagnosis is mainly clinical — from the pattern of symptoms and triggers; blood tests are not usually needed.
- Eosinophils — may be mildly raised in the blood, reflecting allergic inflammation.
- Specific IgE blood tests (or skin-prick testing) — identify the exact allergen(s) when knowing the trigger will guide avoidance or immunotherapy.
- Total IgE — often raised in atopic people but non-specific. Routine bloods are frequently normal; testing is targeted, not automatic.
Symptoms
- Sneezing, often in bouts
- A runny nose with clear discharge, or a blocked, congested nose
- Itchy nose, throat, roof of the mouth
- Itchy, red, watery eyes
- Postnasal drip, throat clearing, cough
- Reduced sense of smell
- Tiredness and poor sleep from nasal blockage
- Seasonal pattern (pollen) or year-round (dust mite, pets)
Related symptoms
Related lab panels
When to discuss with a doctor
Allergic rhinitis is usually managed on the symptoms without tests, starting with allergen avoidance where possible and treatments such as antihistamines and steroid nasal sprays, which are very effective. See a doctor if symptoms are not controlled by these measures, are affecting sleep, work or school, or come with wheezing or breathlessness (which may indicate asthma). Allergy testing (specific IgE or skin-prick) is worthwhile when identifying the exact trigger will change management — for example to guide avoidance or to consider immunotherapy (desensitisation). Sudden swelling of the lips, tongue or throat with breathing difficulty is a different, emergency reaction (anaphylaxis). Mediora.AI can note a raised eosinophil count consistent with allergy; the diagnosis and any allergy testing belong with your doctor.