Acute Allergic Reaction (Urticaria): This is the most common cause of hives in children, often triggered by allergic reactions to foods, insect bites, or medications. The sudden onset of itchy, raised welts is characteristic.

Insect Bite or Sting: Reactions to insect bites or stings can cause hives, especially if the child has been outdoors.
Viral Exanthem: Many viral infections can cause rashes that resemble hives, such as enterovirus or respiratory viruses.
Food Allergy: Common food allergens like peanuts, tree nuts, fish, shellfish, milk, eggs, wheat, and soy can cause hives in allergic children.
Medication Allergy: Certain medications, particularly antibiotics like penicillin, can induce allergic reactions leading to hives.

Anaphylaxis: A severe, life-threatening allergic reaction that can cause hives, along with other symptoms like swelling, difficulty breathing, and a drop in blood pressure. Immediate recognition and treatment are crucial.
Mastocytosis: A condition characterized by an accumulation of mast cells in the skin, which can cause hives and other systemic symptoms.
Autoimmune Disorders (e.g., Lupus, Rheumatoid Arthritis): Though rare in children, these conditions can present with skin manifestations like hives.

Urticarial Vasculitis: An inflammation of the blood vessels that can cause hives, but it's more painful and leaves bruises.
Erythema Multiforme: A skin condition characterized by target-like lesions, which can sometimes resemble hives.
Hereditary Angioedema: A genetic disorder that causes recurrent episodes of severe swelling, which can sometimes be confused with hives.
Parasitic Infections: Certain parasites, like hookworms, can cause hives as part of their infection presentation.