Whether it is a summer visit to the ocean or the waters of the Chesapeake Bay, jellyfish stings are relatively common problems for swimmers,...

Whether it is a summer visit to the ocean or the waters of the Chesapeake Bay, jellyfish stings are relatively common problems for swimmers, waders, and divers in all types of seawaters.  The long tentacles trailing from the jellyfish body can inject victims with venom from thousands of microscopic barbed stingers.

While many types of jellyfish are relatively harmless to humans, some can cause severe pain and are more likely to cause a systemic reaction.  The most common types in our region, including the Bay and the Atlantic, are the sea nettle, the Moon Jelly, and the Lion’s mane jellyfish.  Fortunately, these species cause relatively mild local reactions.  Box jellyfish and the Portuguese man-of-war can cause more severe reactions and are mainly found in the much warmer waters of the tropics and subtropics.

Conditions that increase your risk of getting stung by jellyfish include swimming on a downwind shore,swimming at times when jellyfish appear in large numbers (a jellyfish bloom), swimming or diving in jellyfish areas without protective clothing, playing or sunbathing where jellyfish are washed up on the beach,and swimming in a place known to have many jellyfish.

Jellyfish tentacles contain microscopic barbed stingers. Each stinger has a tiny bulb that holds venom and a coiled, sharp-tipped tube. The jellyfish uses the venom to protect itself and kill prey.  When you brush against a tentacle, tiny triggers on its surface release the stingers. The tube penetrates the skin and releases venom. It affects the immediate area of contact and may enter the bloodstream.  Jellyfish that have washed up on a beach may still release venomous stingers if touched.

Signs and symptoms of jellyfish stings are burning, prickling or stinging pain; red or purplish tracks on the skin (“print” of the tentacles’ contact with your skin); itching; swelling; tingling and numbness and throbbing pain that radiates up a leg or an arm.

Severe jellyfish stings can affect multiple body systems. These reactions may appear rapidly or several hours after the stings. Signs and symptoms of severe stings can be nausea and vomiting; headache; muscle and joint problems; weakness and dizziness; fever; loss of consciousness; difficulty breathing and heart problems.  The severity of your reaction depends on the type and size of the jellyfish; your age, size and general health; how long you were exposed to the stingers and how much of your skin is affected.

Most jellyfish stings get better with simple treatment.  Remove any pieces of jellyfish tentacle and stingers in your skin by rinsing the wound with seawater.  You can also try gently scraping off the stingers with the edge of an ID card or a credit card.  Avoid getting sand on the wound.  Do not rinse with fresh water or rub the area with a towel, as these actions may activate more stingers.

Rinse the affected area with vinegar for about 30 seconds or apply a paste of baking soda and seawater.  Each method may deactivate the stingers of some types of jellyfish. Ice packs may help ease pain.  Over-the counter pain relievers and lotions may help to relieve itching and discomfort.

Remedies that are unhelpful or unproved include: human urine; meat tenderizer; pressure bandages and solvents, such as formalin, ethanol and gasoline.  Severe reactions require emergency medical care.  Seek emergency treatment if stings cover large areas of skin or you have severe symptoms or a serious allergic reaction.

The content in this column is for informational purposes only.  Consult your physician for appropriate individual treatment.  Dr. Reynolds practices Family Medicine in Chesterfield.