What are jellyfish stings?

Stings from jellyfish (stingers) are common, and most of them don't need to be seen by a doctor.

But stings from some box jellyfish are dangerous and can cause a severe reaction or even death. It's important to know what to do if you are stung by a jellyfish.

What symptoms are related to jellyfish stings?

Your symptoms will depend on what type of jellyfish sting you have.

Bluebottle jellyfish

Stings from bluebottle jellyfish (also called Portuguese Man-of-War jellyfish) are very common. Bluebottles are commonly found along the eastern coastline of Australia — especially in Queensland and New South Wales. Their stings are painful, but they don't usually need medical treatment.

Stings can cause:

• intense pain lasting one or more hours
• a red line where your skin was in contact with the jellyfish tentacles, lasting one or more days

Other jellyfish

Other jellyfish that are found in Australian waters are:

• mauve stingers
• hair jellyfish
• jimble and other box jellyfish

These jellyfish may cause:

• pain lasting one or more hours
• a red line at the sting site, lasting one or more days

Major box jellyfish

Major box jellyfish are the most dangerous jellyfish in Australia. They are found in the far north of Australia. Their tentacles are very long and likely to touch more of your skin.

A sting from a major box jellyfish can cause severe pain and red, whip-like lines.

If you get a bad sting, your heart may stop, causing death. This can happen in 20 to 30 minutes.

Other box jellyfish

These types of jellyfish are small, and their sting may not be noticed at first. Irukandji syndrome symptoms can happen 20 to 30 minutes after the sting and include:

• severe pain in your back, abdomen (tummy), chest and muscles
• tachycardia (increased heart rate)
• hypertension (high blood pressure)
• anxiety and agitation
• nausea (feeling sick) and vomiting

In severe cases, it can damage your heart.

What causes jellyfish stings?

A jellyfish sting happens when their tentacles touch your skin. Stinging cells on the tentacle (called nematocysts) shoot poisonous venom into your skin.

How bad your sting is depends on the type of jellyfish and how much of their tentacles touched your skin.

How is the cause of jellyfish stings diagnosed?

Your doctor will ask about your symptoms and whether you saw what type of jellyfish stung you. They will examine the sting area and check your vital signs — your pulse, blood pressure, breathing and temperature.

When should I see a doctor?

See a doctor if you have been stung by a jellyfish and have severe pain that's not improving or other symptoms.

If you think you have Irukandji syndrome, go to hospital.

When to seek urgent care

It can be hard to know which species of jellyfish has stung you.

If you are in the north of Australia — north of Bundaberg in Queensland and Geraldton in Western Australia — and you don't know what type of jellyfish stung you, treat it as a box jellyfish sting.

Get help from a lifeguard if you can.

How are jellyfish stings treated?

Treatment will depend on the type of jellyfish sting you have. Many jellyfish stings can be treated with simple first-aid measures.

First aid for bluebottle jellyfish stings

If you've been stung by a bluebottle:

• wash the sting site with sea water (not fresh water)
• remove any tentacles by hand or wash them off with sea water
• put your affected limb in hot water (45ºC) for 20 minutes; make sure the hot water will not burn you

If you can't put your limb in hot water, try a hot shower or running hot water over the sting site. Hot water is better than ice packs at reducing the pain of bluebottle jellyfish stings.

Do not put vinegar on the sting. It may increase the pain of bluebottle jellyfish stings.

First aid for other jellyfish stings

First aid for other jellyfish stings

• wash the sting site with sea water (not fresh water)
• remove any tentacles by hand or wash them off with sea water
• consider putting your affected limb in hot water (45ºC) for 20 minutes — make sure the hot water will not burn you

Do not put vinegar on the sting. It may increase your pain.

First aid and treatment for major box jellyfish stings

If the person is unconscious, do cardiopulmonary resuscitation (CPR).

First aid for a major box jellyfish sting involves:

• removing any tentacles by hand or washing them off with sea water (not fresh water)
• once the tentacles are removed, putting vinegar on the sting site — vinegar deactivates the stinging cells
• using ice packs

Go to hospital, as you may need treatment with:

• antivenom
• strong pain-relief medicines
• heart monitoring

Treatment for other box jellyfish stings — Irukandji syndrome

If you think you have Irukandji syndrome, go to hospital.

In hospital, you may be given intravenous (IV) medicines to help with your pain. They will also check if your heart has been affected by the jellyfish sting.

Complications of jellyfish stings

Bad bluebottle jellyfish stings may cause blisters that need dressings.

Very rarely, after a bluebottle sting some people have:

• nausea
• vomiting
• abdominal (tummy) pain
• muscle pain
• problems breathing

This happens to less than 1 in 100 people who get stung.

Can jellyfish stings be prevented?

To help prevent jellyfish stings, stay out of the sea when there are warnings about jellyfish — especially during stinger season.

Stinger season is typically from late spring to early autumn. However, it can vary depending on where you are in Australia and the weather conditions.

Don't touch jellyfish in the water or on the beach.

If you go into the sea, wear clothing that covers your skin — a full-body wetsuit and waterproof footwear. You can also buy special stinger suits.

It's a good idea to swim only at patrolled beaches. This way, you are near a lifeguard who can give first aid or call an ambulance if needed.

Resources and support

For advice on jelly fish stings, contact the Poisons Information Hotline on 13 11 26.

The Australian Bites & Stings app contains first aid instructions on what to do if bitten or stung by a venomous creature, and is free to download.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.