Sea urchins belong to a group of about 950 living species of spiny sea animals that are related to starfish and sand dollars. They often have calcium in their spines and may be mistaken for shells or rocks because of their appearance. Their spines are their defense mechanism. Their stings can be extremely painful and can cause extensive damage to the skin, tissue, and even bone. Removal of these spines from our body parts can be distressing similar to removing a large splinter. Sea urchin stings can occur when they are touched or accidentally stepped on.

Most sea urchin stings do not kill you. However, they can result in serious complications if left untreated. Some people may develop an allergic reaction, especially if they are allergic to other stings or bites. Allergic reactions are potentially fatal and require immediate medical attention. Some sea urchins are more dangerous than others because they have venomous spines. These venomous sea urchins are common in the Indian and Pacific oceans. Unlike a sting, a bite does not leave spines behind. Hence, it is best to avoid touching sea urchins.

What are the signs and symptoms of sea urchin sting?

Sea urchin stings cause immediate pain. Their spines cause puncture wounds on the skin, which appear blue-back like a bruise. The puncture wounds can become infected if not treated immediately. The affected area may become tender, red, and swollen.

Multiple deep puncture wounds require immediate medical attention because they can be life-threatening, resulting in respiratory failure and death. The symptoms of sea urchin sting are:

How are sea urchin stings treated?

It is advised to seek medical attention following a sting or bite. However, some first aid measures can help manage the wound and pain. They are:

  • Treatment for a sea urchin sting is its immediate removal. Vinegar dissolves most superficial spines. Therefore, soaking the wound in vinegar solution three or four times a day or applying a wet vinegar compress may help.
  • Hot soaks in a tub of water may help relieve pain.
  • Rarely, a small cut may be required to extract the spine.
  • A spine that has embedded into deeper tissues may need surgical removal by a doctor.
  • Even after the removal of the spine, the pain may continue for days. It is important to note that the pain that lasts beyond 5-7 days indicates an infection or a retained foreign body.
  • G pedicellariae urchin stings are treated by washing the area and applying a mentholated balm.
  • Tetanus prophylaxis should always be given after a sting or bite.
  • Nonsteroidal anti-inflammatory drugs, such as Ibuprofen, can help reduce pain. An antihistamine can help reduce itching.
  • The wound should be kept clean, and an antibiotic ointment can be applied. Antibiotic ointment with hydrocortisone (steroid) helps reduce swelling, redness, and itching.

When to seek medical attention

An allergic reaction following a venomous sea urchin sting or bite can be life-threatening. The following signs and symptoms require immediate medical attention:

  • Difficulty breathing
  • Loss of consciousness
  • Giddiness
  • Mental confusion
  • Mood or behavior changes
  • A rash on a different area of the body from the sting
  • Extensive swelling at the sting
  • Changes in heart rate
  • Loss of consciousness
  • Nausea
  • Vomiting
  • Difficulty breathing
  • A trapped spine under the skin or even after a spine is successfully removed can result in wound infection. Signs of infection include redness, an increase in pain, warmth and tenderness, severe swelling, or fever.


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Medically Reviewed on 3/23/2021
Burke WA, Steinbaugh JR, O'Keefe EJ. Delayed Hypersensitivity Reaction Following a Sea Urchin Sting. Online Wiley Library. Published online May 31, 2007. doi: 10.1111/j.1365-4362.1986.tb04528.x

Barish RA, Arnold T. Sea Urchin Stings. Merck & Co.