How adrenaline works

Anaphylaxis is caused by the sudden release of substances from cells into blood and tissues. These substances, primarily histamine, have an effect on blood vessels and cause swelling in the mouth and throat. Blood pressure falls and abdominal pain can occur. Dizziness, fainting and shock may follow.

Adrenaline rapidly constricts blood vessels and relaxes smooth muscles in the lungs. This helps breathing, stimulates the heart and prevents continued swelling of the face and lips.

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