Sea Urchin Spines: Removal, Aftercare, and When to See a Doctor

Sea urchins are the small, dark, spiny creatures that cling to rocks and reef. Their spines are designed to break off when something disturbs them — meaning they break off when something disturbs you, too. Most people step on them while walking over reef at low tide, or get them in the hands when they grab at rocks during a wipeout.

The spines are calcium carbonate, brittle, and tipped with a mild irritant. Some species have toxic spines that cause more severe pain, but the urchins in Sri Lankan waters are usually the less dangerous kind.

What it feels like

A sharp burning pain at the moment of contact, followed by a deep ache that lasts hours. The puncture marks are tiny but the spines themselves can go deep — sometimes a centimetre or more into the foot. If you bring the foot up and look, you’ll usually see one or more dark spots where spines are embedded.

Removing the spines

This is where most people go wrong. Sea urchin spines are brittle. They break easily when you try to grab them with tweezers. A spine that breaks halfway out is harder to remove than the original spine.

The right approach depends on how many spines are in, how deep, and where:

• Visible, sticking-out spines: gently use clean tweezers to remove them, pulling straight along the angle they went in. Don’t twist.
• Spines that are flush with the skin or just below: do not dig. This causes more damage and usually fragments the spine. Come in and we’ll remove them properly under magnification, often using a small incision.
• Many spines, or spines in the sole of the foot, hands, or near joints: come in. Removal in these locations is finicky and infection-prone, and we can numb the area first.

What about vinegar?

A popular folk remedy is to soak the area in vinegar for thirty minutes, on the theory that vinegar dissolves the calcium carbonate. There is some truth to this — vinegar will slowly soften and dissolve very small fragments — but it doesn’t work fast enough or thoroughly enough to be the main treatment for visible spines. You can soak in vinegar as a first step while you decide whether to remove the larger spines yourself or come to us.

Aftercare

Once the spines are out:

• Wash thoroughly with soap and fresh water
• Apply antiseptic (povidone-iodine or chlorhexidine)
• Cover with a clean dressing
• Take paracetamol for pain
• Stay out of the water until the puncture wounds have closed (usually two to four days)

Watch for signs of infection over the next week: spreading redness, increasing pain, pus, warmth, fever, or red streaks. Spines that were completely removed almost never cause problems. Fragments left behind can cause persistent infection, a small nodule, or what’s called a granuloma — a chronic lump that can take weeks or months to clear up.

When to come in straight away

• Multiple spines, especially in the sole of the foot
• Spines in the hands, near joints, or near the eyes
• Spines that broke off below the skin
• Severe pain that isn’t responding to paracetamol
• Signs of an allergic reaction (swelling beyond the local area, breathing difficulty, dizziness)
• The wound is more than a few hours old and you haven’t been able to remove all the spines

Removal is quick and painless once we’ve numbed the area. We’ll also check whether you need a tetanus booster, and prescribe antibiotics if the wound is high-risk.

This article is general health information and not a substitute for medical advice.