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.
Anaphylaxis is life-threatening, so call 911 right away. If you have an epinephrine auto-injector, use it and repeat after 5 to 15 minutes if your symptoms haven’t improved. You’ll still need medical care right after you give yourself the shots, even if your symptoms seem to stop, because a delayed reaction could still happen.