Hives, also called welts or urticaria, can appear on a toddler's skin in various locations. Hives differ from other general rashes in that the red patches possess well-defined edges, pale centers and red borders and tend to itch. The most common reason hives develop relates to the presence of an allergen. The immune system sends out histamine to fight the allergen, which leads to side effects such as hives.
Nearly any common environmental allergen can cause hives to appear on a toddler's skin. Many are not even true allergens, like pollens or insect bites. Some toddlers have sensitive skin during their early years and develop hives from detergents, personal care products and fragrance products. It can be difficult to pinpoint the exact environmental agent that caused the hives, because the toddler's immune system is reacting unnecessarily. The source of persistent hives can be identified through allergy testing or elimination of potential triggers.
Various toddler food allergies can cause hives. Toddler hives are commonly caused by shellfish, nuts, berries and fish. Toddlers may also react negatively to certain medications or immunizations and develop hives. Sometimes, severe hives occur along with trouble breathing and other serious signs of allergic reaction. When hives occur from the use of medication, it can be difficult to discern if they are due to the illness or the drug.
Because a toddler's immune system is still maturing, it may erroneously treat certain agents like an allergen. When the immune system attempts to fight off the agent, it will send the same histamine into the blood stream, regardless of whether or not the agent needs to be attacked. Examples of when this occurs include sun exposure, heat exposure, cold and various illnesses.