Español+ Flipbook textHives are red, itchy raised welts or patches on the skin.The medical term for hives is urticaria.What is chronic spontaneous urticaria? Chronic = Lasts for longer than 6 weeks Spontaneous = Happens on its own, without an obvious trigger Urticaria = Hives Why do hives happen? Cells in your body store histamine, a chemical released by the immune system when it recognizes a threat.Histamine affects blood vesselsHistamine released by your body opens up your blood vessels to allow for more blood flow. This can lead to skin symptoms like: Swelling Redn...