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Jellyfish Stings: Allergic Reaction

British Columbia Specific Information

Jellyfish found in Canadian coastal waters are capable of stinging, resulting in a mild to moderate amount of pain. If you are stung by a jellyfish in Canadian coastal waters, do not use vinegar for the sting. This may make the sting worse. For information on what to do if you are stung in Canadian coastal waters, visit the British Columbia Drug and Poison Information Centre (Poison Control) website.

If you are concerned about a jellyfish sting or require further information about other marine stings and scrapes, call Poison Control at 1-800-567-8911 toll-free anywhere in British Columbia, or 604-682-5050 in Greater Vancouver.

Overview

The reaction that you have to a jellyfish or Portuguese man-of-war sting depends on many things. The potency of the venom changes with the type of jellyfish and also is stronger during some seasons than in others. Other things that affect the severity of your reaction include:

  • Your size, age, and general health.
  • The location and how much of your body (surface area) was stung.
  • The size or number of jellyfish or tentacles that stung you.

The pain from jellyfish and Portuguese man-of-war stings may be intense and may last for several hours. The skin at the site of the stings may look dusky or bluish purple. Blisters and deep sores (ulcers) may develop. Healing is generally a slow process that may take many weeks. Permanent scars may occur at the site of a sting.

Small children are at risk for stings in the mouth if they put a jellyfish or portion of a tentacle in their mouths. A sting to the mouth or throat can cause sudden and severe swelling, which can be life-threatening.

Problems from jellyfish or Portuguese man-of-war stings may develop right away or be delayed for several hours or days. A severe allergic reaction (anaphylaxis) may affect any body system and require emergency care. Symptoms can include any of the following:

  • Shock
  • Severe pain
  • Swelling of the lips, tongue, mouth, throat, neck, ears, eyelids, palms, or soles of the feet (angioedema). Swelling is most serious when it involves the airway and interferes with breathing.
  • Coughing, wheezing, difficulty breathing, or a feeling of fullness in the mouth, throat, or neck
  • Light-headedness, confusion, or agitation
  • Headache, dizziness, or vertigo
  • Nausea, vomiting, diarrhea, and stomach cramps
  • Fever and chills
  • Hives and flushing of the skin. These symptoms often occur with other symptoms of a severe reaction.
  • Muscle spasm, muscle cramps, joint pain, or generalized aching

Credits

Current as of: November 9, 2022

Author: Healthwise Staff
Medical Review:
William H. Blahd Jr. MD, FACEP - Emergency Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine