Causes and Diagnosis of Allergic Rhinitis in Pediatrics

While a nasal allergy is something that adults and adolescents commonly experience, you don't typically see it in very young children.

This is because of an allergy, by definition, is related to a previous immune response, one in which an immune cell—called an antibody—is produced to defend against a perceived threat. Once an antibody is produced, it remains in the body ready to respond if the threat returns. When it does, the ​immune system can sometimes overreact, triggering a cascade of symptoms we commonly associate with an allergy. 

Because babies and toddlers don't yet have a fully developed immune system, conditions like allergic rhinitis are not all that common. But they do happen, more often in children over four but sometimes in those under two.

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Allergic Rhinitis in Babies

Allergic rhinitis is a type of allergy that affects the nasal passages, causing congestion, runny nose, sneezing, and watery eyes. Doctors tend only to see the condition as a child reaches school age. Before then, allergies are mostly constrained to eczema (atopic dermatitis) or food-related allergies.

But that doesn't mean that allergic rhinitis can't affect young children; it does. In fact, if a child has been exposed to extremely high levels of indoor allergens (such as pet dander, dust mites, cockroaches, or mold), allergic antibodies can develop quickly and lead to the same symptoms seen in adults.

By contrast, outdoor allergens are less commonly associated rhinitis in babies simply because they haven't been around long enough to have experienced the pollen exposure needed to develop a seasonal allergy.

Confirming the Diagnosis

To differentiate between an allergy and other possible causes, the pediatrician would look at the accompanying symptoms. In most cases, a baby with allergic rhinitis would also have eczema, asthma, or symptoms of an adverse reaction to food, medication, or an insect bite. A cold or flu would typically exclude a diagnosis since nasal symptoms are common in both.

If an allergy suspected, the doctor can order an allergy test to confirm the diagnosis. The skin test can either be performed by pricking the top layer of the skin with a diluted allergen (such as mold or pet dander) or by using a thin needle to inject the diluted allergen into the skin.

All told, it takes around 15 minutes for a positive result to be received. The tests, while accurate, should never be used on infants under 6 months.

Other Possible Causes

While an allergy may be suspected, there are numerous other conditions that can mimic the symptoms of rhinitis, including an upper respiratory infection. Although a fever would typically accompany this, it can often be low-grade and hardly noticed.

Additionally, teething can cause an infant to have a runny nose, resulting in the accumulation of mucus and the development of congestion. Adenoid hypertrophy (enlarged adenoids) is also a common cause of chronic congestion in younger children.

If nasal symptoms persist or worsen after treating a cold, flu, or infection, speak with your doctor and ask for a referral to an allergist, ideally one specializing in pediatric allergies.

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  3. Merck Manuals. Adenoid Disorders. Sept 2019.

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