Jellyfish Stings and Man of War Stings

Practical Chemistry to Treat Jellyfish and Man of War Stings

Some beaches offer vinegar to use on jellyfish stings.
Some beaches offer vinegar to use on jellyfish stings. FLPA/Gianpiero Ferrari / Getty Images

You can apply common household chemistry to treat jellyfish and Portuguese man of war stings. However, jellyfish and man of war are two different animals! Here's a look at how to tell them apart and how the chemistry of treating the stings differs depending on what stung you.

Don't Make the Sting Worse!

Do you know what to do if you or someone with you sees a jellyfish or is stung by one? You should know the answer to these questions before you go to the beach, since an encounter with a jellyfish can be a painful or possibly lethal experience.

As a matter of practical chemistry, your biggest risk from a jellyfish or man of war sting may come from improper first aid intended to deal with the venom, so pay attention...

What should you do if you see a jellyfish?

Best Answer: Leave it alone. If it's in the water, get away from it. If it's on the beach and you need to walk around it, walk above it (dune side) rather than below it (surf side), since it may be trailing tentacles. Keep in mind a jellyfish does not need to be alive in order to sting you. Detached tentacles are capable of stinging and releasing venom for several weeks.

My Actual Answer: It depends what kind of jellyfish it is. I realize if it looks like floating jelly, it's considered a 'jellyfish', but there are different types of jellyfish and also animals that look like jellyfish but are something else entirely. Not all jellyfish can hurt you. Some jellyfish are either nonvenomous or else their stinging cells can't penetrate your skin.

What do you do when you see one of these jellyfish? If you are a kid, you'll probably pick it up and throw it at another kid (unless it's alive, then be kind and let it be). Most parts of the world have non-venomous jellyfish. They tend to be easy-to-spot. It's the ones you don't see that present the biggest threat.

Many jellyfish are transparent. You probably won't see them in the water, so if you are stung you won't know exactly what got you. If you see a jellyfish and don't know what type it is, treat it like a venomous species and get away from it.

How do I treat a jellyfish sting?

Answer: If you know the victim is allergic to insect stings, seek medical attention immediately. People who are allergic to bees and wasps may experience a dangerous allergic reaction to a jellyfish sting. Otherwise, act quickly and calmly to remove the tentacles, stop the stinging, and deactivate any toxin.

Here is where people get confused, because the best steps to take depend on what type of animal caused the sting. Here's a good basic strategy, especially if you don't know what caused the sting:

  1. Get out of the water. It's easier to deal with the sting and it takes drowning out of the equation.
  2. Rinse the affected area with sea water. Do not use fresh water! Fresh water will cause any stinging cells that haven't fired (called nematocysts) to do so and release their venom, possibly worsening the situation. Do not rub sand on the area (same reason).
  3. If you see any tentacles, carefully lift them off the skin and remove them with a stick, shell, credit card, or towel (just not your bare hand). They will stick to swimwear, so use caution touching clothing.
  1. Keep an eye on the victim. If you see any signs of an allergic reaction, call 911 immediately. Symptoms could include difficulty breathing, nausea, or dizziness. Some redness and swelling is normal, but if it spreads outward from the sting or if you see hives on other parts of the body, that could indicate an allergic response. If you suspect a reaction, do not hesitate to seek medical attention!
  2. Now... if you are sure the sting is from a jellyfish and not a Portuguese Man of War (shown below, the Man of War is not a true jellyfish) or any other animal, you can use chemistry to your advantage to inactivate the toxin, which is a protein. (Technically the venom tends to be a mixture of polypeptides and proteins including catecholamines, histamine, hyaluronidase, fibrolysins, kinins, phospholipases, and assorted toxins). How do you inactivate proteins? You can change the temperature or acidity by applying heat or an acid or base, such as vinegar or baking soda or diluted ammonia, or even an enzyme, such as the papain found in papaya and meat tenderizer. However, chemicals may cause the stinging cells to fire, which is bad news for someone allergic to jellyfish toxin or anyone stung by a Portuguese Man of War. If you do not know what caused the sting or if you suspect it is from a Man of War, do not apply fresh water or any chemical. Your best course of action is to apply heat to the affected area, since it penetrates the skin and inactivates the toxin without causing more venom to be injected. Also, heat quickly helps alleviate the pain of the sting. Hot seawater is great, but if you don't have that handy, use any warmed object.
  1. Some people carry aloe vera gel, Benadryl cream, or hydrocortisone cream. I'm not sure how effective the aloe is, but Benadryl is an antihistamine, which may help limit an allergic response to the sting. Hydrocortisone can help reduce inflammation. If you seek medical attention and used Benadryl or hydrocortisone, be sure to alert the medical professionals. Acetaminophen, aspirin, or ibuprofen commonly are used to relieve pain.