Ask a Maui Doctor: What Should I Do If I Step on Wana?

Doctors at Minit Medical answer some of the questions submitted by readers.

Active sea urchin at Night at the Aquarium. Photo by Kiaora Bohlool.

Each week, a doctor from Minit Medical Kahului or Lahaina will answer questions that have been submitted by readers. Submit your own medical related questions to our doctors at [email protected].

Questions submitted will be considered for inclusion in the “Ask a Maui Doctor” column.

Q: What should I do if I step on Wana?

A: Wana (pronounced Vah-nah), or sea urchins, are marine creatures with pointy, black needles-like spines found in coastal waters. They are found in coastal areas throughout the world including Hawai‘i. They are also known as sea hedgehogs because of the sharp needle-like spines emanating from their spherical body.

While they feed on algae and move very slowly, they commonly cause injuries when people inadvertently step on or kick them while in shallow ocean waters. They are a common injury at Minit Medical Urgent Care.

Luckily sea urchins found in Hawai‘i do not contain poison that could be deadly to humans and most sea urchin spines do not need surgical removal.

The needle sharp wana spines are also fragile and brittle and brake away from the sea urchin easily, usually leaving the spines embedded in a person’s skin. The initial puncture will cause pain and a small amount of toxin is also released causing additional stinging and pain. You may notice a purplish-black discoloration in the skin around the punctured area because of this. The pain usually subsides over 3-7 days depending on size and number of spines.

If you get “stung” by a sea urchin while in the water, you should remain calm and exit the water so that you can clean and inspect the wound. Any large spines that you can grasp should be carefully pulled out of the skin if possible. The spines are very brittle and have microscopic barbs that make it very difficult to remove the spines. They often splinter apart when trying to remove them. Any spines that may have entered a joint or punctured down to a tendon (especially in the hand) need medical evaluation to see if surgical removal is required.

If spines are less than 1 mm diameter and not involving a joint or tendon, they can usually be soaked in white vinegar three times daily to ease the pain and help dissolve remaining spines. Spines 1 mm diameter or larger may need surgically removed so that they do not cause a granuloma or infection, so you should have them checked out by a doctor.

It is important that your tetanus vaccination has been updated within the past 10 years. You should monitor the wounds for any signs of infection such as redness or worsening pain that may need an antibiotic. Sometimes problems do not arise until 2-4 weeks after the initial injury. If you develop pain or swelling to the area of a former wana puncture, you should see your doctor to make sure you have not developed a granuloma that may need to be surgically removed. If you have any concerns or questions about your wana injury, stop by Minit Medical Urgent Care to have it looked at.

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If you think you may have a medical emergency, call your doctor or 911 immediately. Reliance on any information provided by in this article is solely at your own risk.