How to Treat a Jellyfish Sting


First Things First: Be Careful and Watch for Allergic Reaction

The problem with jellyfish is that they sneak up on you. Swimmers are cruising along in the ocean one minute, and feeling the sting of the jellyfish the next.

Jellyfish tentacles can still sting even after they've been ripped from the body of the jellyfish. Jellyfish tentacles (and their nematocysts) that are still on the patient's skin are capable of stinging you if your bare skin comes in contact with them so keep that in mind.

Take These Steps

There are three steps to treat a jellyfish sting:

  1. The Rinse Step
  2. The Pluck-Those-Stupid-Tentacles-Off-Me-Now Step
  3. The Hot Bath Step

For best results, follow them in order. Ibuprofen (Advil, Motrin) and acetaminophen (Tylenol) will help relieve pain. Ice or heat may also help. Mild itching may be helped with diphenhydramine (Benadryl), but watch for anaphylaxis, a deadly allergic reaction that can result in:

Anaphylaxis can also cause a drop in blood pressure known as anaphylactic shock.

If the species is known to be box jellyfish (Chironex fleckeri) or Irukandji (Carukia barnesi), get emergency medical help immediately.

What Is a Jellyfish Sting?

Jellyfish stings come from cells called nematocysts found the long tentacles that trail the bell-shaped jellyfish and in some species on the bell itself. These cells inject a protein-based venom. The most dangerous reaction to most jellyfish stings is the possibility of severe allergic reactions. However, some species of jellyfish have venom strong enough to kill even if you're not allergic.


The Rinse Step

Rinse away the tentacles using hot water if possible (see the Hot Bath Step for how hot). If heated water isn't available, use salt water rather than fresh. Fresh water may worsen the stinging pain.

Plain white distilled vinegar (acetic acid)—like you would find in your kitchen—has long been the standard first aid treatment for jellyfish stings. Its use has become controversial in the last few years and several studies leave us questioning whether vinegar really works. Vinegar is still recommended for use on box jellyfish stings. If it's available I'd give it a try, but don't stop rinsing with seawater while somebody is fetching the vinegar.

One home remedy suggests peeing on the sting. Urine will probably not work on a jellyfish sting. Some patients have reported pain relief, but urine does not always have enough acid to neutralize the venom.

The examples of urine working to reduce pain probably would have had the same or better response from rinsing with sea water or hot water. Use hot water whenever possible.


The Pluck-Those-Stupid-Tentacles-Off-Me-Now Step

Peel off  any remaining tentacles with a gloved hand, stick, shell or tweezers. Be careful not to get the tentacles on yourself or on your clothing. If you use bare hands to pluck tentacles off, you'll most likely get stung on the fingers.

That's also why it's so important to remove them. If you don't, the patient will keep getting stung until all the nematocysts are used up.


The Hot Bath Step

Immerse the stung area in hot water. How hot is hot? There isn't much evidence that water under 102 degrees is going to help and a lot of evidence that water over 122 degrees is extremely effective.

The general rule is to have the patient either shower or immerse the sting in the hottest water he or she can stand. Work up to the heat and be careful not to scald (burn) the patient.

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