A toddler with a persistently runny nose, frequent sneezing, or eczema that never fully clears may have a household allergy. Unlike pollen allergy, which produces symptoms in spring and summer, household allergen sensitisation causes symptoms throughout the year, and the home – the place children spend the most time – is often the primary source of exposure.
Healthbooq covers children's health and allergy management in the early years.
The Main Household Allergens
House dust mite (HDM). The most common indoor allergen worldwide. House dust mites are microscopic arachnids that live in bedding, carpets, soft furnishings, and soft toys. They feed on shed skin cells and thrive in warm, humid conditions. The allergen is not the mite itself but its faecal particles, which become airborne when disturbed and are inhaled or deposited on skin. Professor Adnan Custovic at Imperial College London has been central to UK research on dust mite sensitisation patterns in children.
Pet dander. The proteins responsible for cat and dog allergies are found in animal saliva, skin flakes (dander), and urine, not solely in the fur. For this reason, "hypoallergenic" breeds are not genuinely allergen-free. The primary cat allergen (Fel d 1) is lightweight and becomes widely distributed in any home where a cat lives – including homes where the cat has since been rehomed, as allergen levels can remain elevated for months.
Mould spores. Indoor damp and condensation create conditions for mould growth (primarily Cladosporium, Alternaria, and Aspergillus species). Mould allergy can cause rhinitis and exacerbate asthma, and is particularly associated with properties with visible damp or poor ventilation.
Cockroach allergens. In urban environments and social housing, cockroach allergens in dust are a significant contributor to perennial rhinitis and asthma. This is less commonly discussed than mite or pet allergy but is clinically important in affected households.
Recognising Household Allergy in a Toddler
Household allergy should be suspected when symptoms are perennial (year-round) rather than seasonal; when symptoms improve when the child is away from home (holidays, visits to relatives with different home environments) and worsen on return; or when symptoms are clearly worse in specific rooms or environments (a child who sneezes more in their bedroom than elsewhere may have a dust mite allergy centred on the bedding).
Symptoms include: persistent clear nasal discharge; frequent sneezing; nasal blockage; itchy nose, eyes, and throat; and in some children, exacerbation of asthma or eczema.
Diagnosis
Allergy testing for environmental allergens uses two main methods. Skin prick testing introduces small amounts of standardised allergen extracts into the skin via a lancet and measures the wheal (raised area) response after 15 minutes. A wheal of 3mm or more than the negative control is considered a positive result. Specific IgE (sIgE) blood testing measures allergen-specific antibody levels in the blood and produces quantitative results.
Testing is appropriate where the history is suggestive and treatment decisions will be guided by the result. For straightforward mild rhinitis managed with antihistamines, formal testing may not change management. For moderate-to-severe symptoms, identifying the specific allergen guides avoidance measures.
Management
Allergen avoidance. The evidence base for dust mite avoidance measures is mixed. Studies using impermeable mattress covers show benefit when used consistently with pillowcase and duvet covers. Weekly washing of bedding at 60°C or above kills mites; drying toys in a freezer overnight then washing at cold temperatures can reduce mite burden in soft toys. Air purifiers with HEPA filters reduce airborne allergen levels in rooms.
For pet allergy, the most effective measure is rehoming the pet, but this is rarely an option families choose. Regular vacuuming with HEPA-filtered vacuums, washing the pet regularly, and keeping pets out of the child's bedroom reduce allergen load without eliminating it.
Medical treatment. Non-sedating antihistamines (cetirizine or loratadine at age-appropriate doses) reduce rhinitis symptoms. Intranasal corticosteroid sprays (fluticasone, mometasone) are effective for persistent rhinitis in children and are now available over the counter in some formulations. Allergen immunotherapy (SCIT or SLIT) is available for house dust mite allergy in children over 5 in specialist settings.
Key Takeaways
Household allergies – also called perennial or environmental allergies – are caused by allergens present year-round in the home environment, primarily house dust mites, pet dander, and mould spores. They are among the most common causes of persistent rhinitis and eczema in toddlers and young children. Diagnosis involves a history of symptoms that persist year-round (in contrast to seasonal pollen allergy), worsening in specific environments, and is confirmed by skin prick testing or specific IgE blood tests. Management involves both allergen avoidance measures (particularly for dust mite allergy) and appropriate treatment of symptoms (antihistamines, nasal sprays, topical treatments for eczema).
