Sea lice are not true lice but rather the microscopic, stinging larvae of certain marine cnidarians, such as thimble jellyfish and sea anemones. These tiny larvae are nearly transparent, making them difficult to see in the water. Exposure typically occurs when swimmers enter waters where these larvae are present, particularly during warmer months when their numbers are higher. The larvae become trapped against the skin, often in areas covered by swimwear, leading to irritation.
How Long Sea Lice Symptoms Last
The duration of sea lice symptoms, known as seabather’s eruption, typically ranges from a few days to a week. However, the rash can persist for up to two weeks, and in some instances, severe reactions might last for a month or even up to two months.
Several factors can influence how long symptoms endure, including the number of stings received and an individual’s sensitivity to the toxins. Prompt removal of affected clothing and rinsing the skin immediately after exiting the water can help minimize the reaction and potentially shorten its duration. Children may experience more severe symptoms and a longer recovery period. If symptoms persist beyond two weeks, worsen, or are accompanied by fever, nausea, or signs of infection, medical consultation is appropriate.
Identifying Sea Lice Rash
A sea lice rash typically manifests as small, red, and intensely itchy bumps or blisters on the skin. These lesions are often concentrated in areas covered by swimwear, where the larvae become trapped and release their stinging cells. Common areas include the groin, buttocks, chest, abdomen, and sometimes areas with body hair like the neck.
Swimmers might first notice a prickly or stinging sensation while in the water or immediately upon exiting. The rash usually develops within minutes to several hours after exposure, often appearing within 24 hours. This pattern of eruption, particularly under swimwear, helps differentiate it from other skin irritations or insect bites, such as swimmer’s itch, which tends to appear on exposed skin and is caused by freshwater parasites.
Alleviating Discomfort
Managing the discomfort of a sea lice rash involves immediate and at-home care. Rinsing the affected skin with fresh water soon after leaving the ocean is a helpful initial step, ensuring to remove swimwear first. Applying a diluted vinegar solution or rubbing alcohol to the stung areas can help neutralize any remaining toxins.
Over-the-counter hydrocortisone cream (1%) applied two to three times daily can reduce itching and inflammation. Oral antihistamines, such as fexofenadine, diphenhydramine, or cetirizine, can also provide relief by addressing the allergic reaction. Cool compresses or ice packs applied for up to 15 minutes at a time, may help ease inflammation and itching. Avoid scratching the rash, as this can lead to skin breakdown and secondary bacterial infections. If the rash is severe, spreads, shows signs of infection (like pus, increased warmth, or fever), or if general symptoms such as nausea or chills occur, seeking medical attention is advisable.
Preventing Future Exposure
Minimizing the risk of future sea lice encounters involves several practical strategies. Checking local beach advisories or warning flags before swimming can indicate the presence of marine stingers. Avoiding swimming during peak sea lice season, typically from May through August, can also reduce exposure.
Wearing protective swimwear, such as rash guards or full-body “stinger suits,” can create a physical barrier against the larvae. These garments are designed to cover more skin and are often made of tightly woven fabrics. Immediately after swimming, remove swimwear and rinse off thoroughly with fresh water. Washing swimwear in hot water and drying it in a machine can help eliminate lingering larvae and their stinging cells. Some sunscreens or lotions may offer limited protection by creating a barrier on the skin.