Urticaria affects about one in ten children. The most common cause of these sudden rashes is a viral infection, but there are other triggers for hives in children. 

Urticaria is the sudden occurrence of small red or pink pimples raised in patches, resembling nettle bites. It is itchy and most commonly appears on the arms, legs and trunk. Hives sometimes cause swelling or edema of the face and extremities. 

A distinction is made between acute urticaria and chronic urticaria. Acute or superficial urticaria is characterized by the sudden appearance of red papules that itch and then disappear in a few minutes or hours (a few days maximum) without leaving a scar. In chronic or deep urticaria, the rashes persist for more than 6 weeks.

Between 3,5 and 8% of children and 16 to 24% of adolescents are affected by urticaria.

In the infant

The most common cause of hives in infants is food allergies, especially cow’s milk protein allergy. 

In children

Viruses

In children, viral infections and taking certain medications are the main triggers of hives. 

The viruses most often responsible for urticaria in children are the influenza virus (responsible for influenza), adenovirus (respiratory tract infections), enterovirus (herpangina, aseptic meningitis, foot, hand and mouth disease), EBV (responsible for mononucleosis) and coronaviruses. To a lesser extent, the viruses responsible for hepatitis can cause urticaria (in a third of cases it is hepatitis B). 

Medication

The drugs that can trigger urticaria in children are certain antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol or codeine-based drugs. 

Food allergies

In urticaria caused by a food allergy, the responsible foods are often cow’s milk (before 6 months), eggs, peanuts and nuts, fish and shellfish, exotic fruits and additives food. 

Insect bites

Urticaria in children can also appear after an insect bite, including wasp, bee, ant, and hornet stings. More rarely, urticaria is of parasitic origin (in endemic areas). 

The temperatures

Finally, the cold and sensitive skin can lead to hives in some children.  

Diseases

Much more rarely, autoimmune, inflammatory or systemic diseases sometimes trigger hives in children.

Treatments for acute urticaria 

Acute urticaria is impressive but often mild. Allergic forms resolve spontaneously within a few hours to 24 hours. Those related to a viral infection can last several days, even several weeks for parasitic infections. If the hives last more than 24 hours, an antihistamine should be given to the child for about ten days (until the hives go away). Desloratadine and levocetirizine are the molecules most used in children. 

If the child has significant angioedema or anaphylaxis (an exacerbated allergic reaction with respiratory, digestive and swelling of the face), treatment consists of an emergency intramuscular injection of epinephrine. Note that children who have already experienced a first episode of anaphylactic shock must always carry a device with them allowing the self-injection of adrenaline in the event of a recurrence. Fortunately, two-thirds of children who have had an episode of hives will never have another episode. 

Treatments for chronic and / or recurrent urticaria

Chronic urticaria resolve spontaneously in most cases after an average duration of 16 months. Age (over 8 years old) and female sex are factors that improve chronic urticaria. 

Treatment is based on antihistamines. If the urticaria is still correlated with a viral infection or with taking medication, the antihistamine should be taken by the child in risky situations. If daily chronic urticaria has no known cause, the antihistamine should be taken over an extended period (several months, repeated if the urticaria persists). Antihistamines help stop itching.