Allergic Rhinitis

Allergic Rhinitis (Hay Fever)

Allergic rhinitis is a common allergic condition in which the immune system reacts to airborne allergens such as pollen, dust mites, or pet dander. This triggers inflammation in the nasal passages and leads to symptoms like sneezing, congestion, and itching. It is closely associated with asthma, eczema, and other atopic conditions.

On blood tests, allergic rhinitis is most often reflected by elevated eosinophils, one of the key white blood cell types involved in allergic responses. This can also contribute to an increased MXD% on a CBC, since eosinophils are part of the mixed cell group.

Why This Matters for Your Blood Test Results

• Allergic rhinitis commonly raises eosinophil levels

• Elevated eosinophils are the most frequent cause of a high MXD%

• Total IgE is often elevated in allergic individuals

• Changes are usually mild and not dangerous

• Levels may fluctuate with allergen exposure (e.g., pollen season)

If your results show mildly elevated eosinophils or MXD and you have allergy symptoms, allergic rhinitis is one of the most likely explanations.

Types of Allergic Rhinitis

Seasonal (Hay Fever)
Triggered by outdoor allergens:

• Tree pollen (spring)

• Grass pollen (early summer)

• Weed pollen (autumn)

Symptoms occur at specific times of year and often follow predictable patterns.

Perennial
Driven by indoor allergens:

• House dust mites

• Mould

• Pet dander

Symptoms persist year-round and can be harder to link to a specific trigger.

Symptoms

• Frequent sneezing (often in bursts)

• Runny nose with clear, watery discharge

• Nasal congestion and blockage

• Itching of the nose, eyes, or throat

• Red, watery, or swollen eyes (allergic conjunctivitis)

• Postnasal drip and throat clearing

• Fatigue, often due to disrupted sleep

Symptoms typically worsen during periods of high allergen exposure.

Causes and Triggers

Allergic rhinitis is caused by an IgE-mediated immune response to allergens. When exposed, the immune system releases histamine and other inflammatory chemicals, leading to symptoms and eosinophil activation.

Common triggers

• Outdoor: Tree, grass, and weed pollens

• Indoor: House dust mites, mould, pet dander

• Occupational: Flour dust, latex, animal allergens

Risk factors

• Personal or family history of asthma, eczema, or food allergy

• Early exposure to tobacco smoke or air pollution

Diagnosis

Allergic rhinitis is primarily diagnosed based on symptoms and exposure patterns. Testing can confirm sensitisation and identify triggers:

• Skin prick testing — first-line test to detect allergen-specific IgE

• Specific IgE blood testing (ImmunoCAP) — useful when skin testing isn’t possible

• CBC with differential — may show elevated eosinophils or MXD%, supporting an allergic cause

Treatment

Intranasal corticosteroids
(fluticasone, mometasone, budesonide)
→ Most effective first-line treatment; reduce inflammation and congestion

Antihistamines
(cetirizine, loratadine, fexofenadine)
→ Help relieve sneezing, itching, and runny nose

Allergen avoidance
→ Reduce exposure (e.g., pollen control, dust mite measures, limiting pet exposure)

Allergen immunotherapy
→ Long-term treatment (3–5 years) that can reduce sensitivity and improve symptoms
→ Consider for moderate-to-severe cases not controlled with medication

FAQ

Can allergic rhinitis cause abnormal blood test results?
Yes. It commonly leads to elevated eosinophils and may also increase MXD%. Total IgE is often elevated as well.

Is allergic rhinitis serious?
It is not life-threatening, but it can significantly affect sleep, concentration, and daily functioning. It is also closely linked to asthma.

Is allergic rhinitis the same as a cold?
No. Allergic rhinitis causes itching, sneezing, and clear discharge without fever. Colds are caused by viruses and usually resolve within 7–10 days.

Related Biomarkers

• Eosinophils — most directly elevated in allergic conditions

• MXD% (Mixed Cells) — increases when eosinophils rise

• Total IgE— often elevated in atopic individuals

• Specific IgE — identifies sensitivity to individual allergens

Tracking these markers over time in HealthMatters can help identify patterns of allergic response and monitor treatment effectiveness.

Bottom Line

Allergic rhinitis is one of the most common causes of mild abnormalities in blood tests related to the immune system — especially elevated eosinophils and MXD%. In most cases, these changes are benign and reflect a normal allergic response, particularly when symptoms align with allergen exposure.