Treatment for Sea Urchin Spines in the Foot

Updated March 23, 2017

The sea urchin is a small marine animal that gathers in large colonies in shallow waters. People swimming or surfing close to shore may accidentally step on these creatures and have their feet punctured by sharp spines that protrude from the sea urchin's body. The sea urchin also has small venomous folds of skin known as pedicellaria, which can attach themselves to the intruder's body. The result is a painful injury that needs swift treatment.


Spines and the venom released by pedicellaria can create pain, irritation, redness and swelling of the skin. The pain level can be intense if multiple spines and pedicellaria come into contact with the skin. If the injury goes untreated, it can cause shock, breathing problems, paralysis and a dangerous infection.

Immediate Treatment

The injured foot should be soaked in a very hot, antiseptic hydrogen peroxide solution for at least an hour. Suba instructor Bill Chambers recommends vinegar as a treatment. The hot water helps dissolve the toxins, while the soaking softens the wound area and helps the removal of foreign bodies. The spines, which are thin and fragile, can be pulled carefully straight out of the wound a pair of tweezers. The pedicellaria can be removed by applying soap or ointment to the affected area and scraping them away with a safety razor.

Wound Cleansing

After the foreign bodies are removed, the wound should be thoroughly cleaned with soap and warm water and flushed. The foot should be elevated and the wound should remain open for faster healing and lessening of skin irritation. Do not bandage the wound or cover it with tape or gauze. Continue soaking the injury in hot water mixed with Epsom salts or hydrogen peroxide; this will help prevent infection.

Antiobiotic Treatment

Topical antibiotics should be applied to the wound area. If an infection begins, indicated by swelling and redness, you should seek professional medical help. A doctor will surgically remove any deep-seated spines that remain and prescribe oral antibiotics to fight the infection. If pain and skin irritation persists, take over-the-counter pain medication such as Motrin or Tylenol. If the spines enter the ankle joint, tenosynovitis or an inflammation of joint tissue may result, requiring surgical treatment.


Some discolouration of the skin is a normal result of the released venom and will gradually disappear. Spine fragments are made of calcium carbonate, the same basic material of human bones, and if left in the skin will gradually dissolve or drop out of the wound.

To protect yourself, remember that it's always best to wear rubber-soled, waterproof sandals or flip-flops when wading in shallow waters.

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About the Author

Founder/president of the innovative reference publisher The Archive LLC, Tom Streissguth has been a self-employed business owner, independent bookseller and freelance author in the school/library market. Holding a bachelor's degree from Yale, Streissguth has published more than 100 works of history, biography, current affairs and geography for young readers.