Limu - Stinging Seaweed

Limu - Stinging Seaweed
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Learn to avoid and treat stings from limu, the stinging seaweed.

• General: DIY / How-To • General: Educational • General: Guide

Guide Series: Hawaii Dangers
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Stinging Seaweed Disease, or Limu as it's often called is a skin irritation that comes from direct exposure to a poisonous algae known as Lyngbya Majuscula. This Limu or Lyngbya is a very fine, hairlike seaweed that is a dark brown color and found worldwide. That means it's also here in the Hawaiian Islands but the good news is that it only occurs at certain times of the year, often in the summer time, and only in some places.

How Do You Get Stung?

The most common way to get stung by this seaweed is from direct exposure as you swim or wade in waters where it grows. For some people it cause a painful rash and for others it does nothing at all. The seaweed tends to get under your bathing suit which gives it more time to cause the rash and irritation on your skin.

Areas that aren't covered by a swimsuit often don't get the rash, but there are plenty of exceptions. It really depends on each person as well as how long they were exposed. So going nude isn't the solution!

Is It Painful?

If your body is more sensitive to the Lyngbya sting then you may develope a red rash much like a burn. It may blister and lead to peeling along with itching and/or a burning feeling. As if that wasn't enough, the little devil adds insult to injury by often appearing in the genital and anal areas of your body. Men may even see a swelling of the scrotum. Limu, the gift that keeps on giving.

In some cases there have been reports of swollen eyes, nose and throat irritations, headaches, skin sores, and fatigue. Any of these symptoms can start right away or several hours after exposure. Most of these issues go away after 4 to 48 hours but in more serious cases it can last up to 12 days.

How To Avoid Stinging Seaweed

Stay out of the ocean, of course. Yes, we know, you're here in Hawaii and that's simply not an option. Abstinence rarely is! The next best option is to avoid swimming where Lyngbya has been reported and since it's not all over the place all the time this should be fairly easy so pay attention to any signage at the beach you're going to. Also, talk to lifeguards about current conditions and concerns before getting in the water.

Regardless of all of that, make sure to always shower off well after getting out of the ocean. Then, as soon as you get back to your bathroom shower again with plenty of soap and thoroughly wash swimsuits, towels, and swim gear to help clear off any algae that left the beach with you.

I Got Stung, Now What?

The first step is to remove any seaweed and foreign objects from your suit and body, ideally with a stick or towel rather than bare hands. You'll now want to wash your body and swimwear with soap.

Stinging seaweed pain can be treated much as you would a sunburn. Try putting some wet towels on the infected areas along with soothing creams (hydrocortisone-based ointments, etc). This should help deal with the pain and itching until it goes away. Benadryl or antihistamines may also help but always consult a doctor when in doubt.