Symptoms of jellyfish stings include: 
Burning, prickling, stinging pain
Welts or tracks on the skin — a "print" of the tentacles' contact with the skin
Itchiness (pruritus)
Swelling
Throbbing pain that radiates up a leg or an arm
 Severe jellyfish stings can affect multiple body systems. These reactions may appear rapidly or several hours after the stings. Symptoms of severe jellyfish stings include: 
Stomach pain, nausea and vomiting
Headache
Muscle pain or spasms
Faintness, dizziness or confusion
Difficulty breathing
Heart problems
 The severity of a reaction depends on: 
The type and size of the jellyfish
The age, size and health of the person affected, with severe reactions more likely in children
How long the person was exposed to the stingers
How much of the skin is affected
