Your immune system makes histamines to help get allergens out of your body.
Hives are patches, red bumps, or welts that can appear anywhere on your skin without much warning. Pinpoint possible triggers of this reaction and learn what you can do while you wait for swelling to disappear.
It's what happens when your immune system reacts to something that’s usually harmless. Those triggers, which doctors call "allergens," can include pollen, mold, and animal dander, certain foods, or things that irritate your skin.
Allergies are very common. At least 1 in 5 Americans has one.
