Box jellyfish stings are extremely painful. Some symptoms can arise hours to weeks after a sting, but the most deadly appear immediately. They include:
- Red whip-shaped lesions on the skin called “wheals”
- Blistering and burning at the site of the sting
- Severe abdominal pain
- Chest pain
- Shock
- Fever or chills
- Muscle spasms
- Sweating
- Nausea or vomiting
When a sting is fatal, death is usually due to cardiac arrest. Experts think the poison affects the heart directly.