Sea lice refers to the microscopic larvae of certain jellyfish or sea anemones. These tiny marine creatures are nearly invisible to the naked eye as they float in ocean waters. When these larvae become trapped against a swimmer’s skin, often under swimwear, they release stinging cells known as nematocysts. This discharge results in an irritating rash, which can affect anyone exposed to these larvae in warm ocean waters.
Identifying Sea Lice Reactions
The characteristic rash caused by sea lice larvae is medically known as “seabather’s eruption.” While some individuals may experience a prickly or stinging sensation while still in the water, the rash typically appears anywhere from a few minutes to several hours after exiting the ocean. This reaction often manifests as small, itchy, red bumps or blisters, sometimes clustering together to form larger irritated areas. The rash commonly develops in areas covered by swimwear, hair, or other clothing, as these materials trap the larvae against the skin.
Beyond the skin irritation, some people, particularly children, may experience additional symptoms such as headaches, nausea, fatigue, or a low-grade fever. Seabather’s eruption is distinct from swimmer’s itch, which is caused by parasites found primarily in freshwater and affects exposed skin.
Treating Sea Lice Stings
Treating sea lice stings involves immediate steps to manage symptoms. Remove swimwear immediately after leaving the water. Avoid showering with freshwater while still wearing contaminated swimwear, as freshwater can trigger remaining larvae to discharge more stinging cells. Instead, rinse the body with saltwater or apply diluted vinegar to neutralize toxins on the skin, then thoroughly wash affected areas with soap and fresh water.
Over-the-counter treatments can provide significant relief for itching and inflammation. Apply a 1% hydrocortisone cream to the rash several times a day to reduce redness and itchiness. Oral antihistamines, such as diphenhydramine or cetirizine, can also calm the allergic reaction and reduce itching. For pain, NSAIDs like ibuprofen (avoid aspirin in children) and soothing remedies such as cool compresses or oatmeal baths can ease burning and itching. Resist scratching the rash, as this can break the skin and lead to secondary bacterial infections.
Preventing Sea Lice Exposure
Proactive measures can reduce the likelihood of encountering sea lice and developing a rash. Check local beach reports and warnings for advisories about stinging marine organisms before swimming. Outbreaks of sea lice larvae are most common in warm ocean waters, typically from March through August, with peak occurrences between April and July in regions like the Gulf of Mexico and the Caribbean Sea. If sea lice are known to be present, avoid swimming in those areas during peak season.
Immediately after swimming, remove swimwear promptly and shower thoroughly. This helps dislodge larvae before they become trapped and triggered. Wearing tight-fitting swimwear or rash guards may reduce the area where larvae can become trapped against the skin. After use, wash swimwear thoroughly in hot water with detergent and dry using heat to kill any remaining larvae and prevent re-exposure.
When to Seek Medical Attention
While most sea lice reactions are mild and resolve with home care, there are instances when medical attention becomes necessary. If symptoms persist or worsen despite home treatments, or if the rash shows signs of infection such as increased pain, tenderness, warmth, swelling, pus, or red streaks, a doctor should be consulted. Seek immediate medical care for severe systemic reactions, including a high fever, chills, persistent nausea, vomiting, abdominal cramps, or difficulty breathing.