Department of Disease Control Issues Warning: Beware of Blue Dragon Sea Slugs and Bluebottle Jellyfish — Follow Safety Signs for Safe Tourism
The Department of Disease Control (DDC) has issued a safety advisory for tourists to be cautious of Blue Dragon sea slugs and Bluebottle jellyfish. According to the Upper Andaman Sea Marine and Coastal Resources Research Center, reports from local network groups and lifeguards indicated that several Blue Dragons were found washed ashore at Karon Beach, Phuket. Upon inspection on August 12, 2025, the species was identified as Glaucilla sp., a type of blue sea slug.
The Department of Disease Control (DDC) has issued a safety advisory for tourists to be cautious of Blue Dragon sea slugs and Bluebottle jellyfish. According to the Upper Andaman Sea Marine and Coastal Resources Research Center, reports from local network groups and lifeguards indicated that several Blue Dragons were found washed ashore at Karon Beach, Phuket. Upon inspection on August 12, 2025, the species was identified as Glaucilla sp., a type of blue sea slug.
Blue Dragons are marine creatures that accumulate venom from their prey, which can cause burning pain, skin irritation, or red rashes upon contact. The severity of symptoms varies depending on an individual’s immunity. These small, invertebrate sea creatures are striking in appearance, with shimmering blue-silver bodies, and measure about 1–5 centimeters in length. They float near the water surface, sustained by seawater’s surface tension, and are carried along by ocean currents since they cannot swim independently.
On August 14, 2025, the DDC stated that Blue Dragon sea slugs feed on venomous jellyfish, particularly the Bluebottle jellyfish, and store the stinging cells within their bodies for defense. Contact with the creature can cause a painful sting similar to that of a jellyfish. Although no deaths have been reported in Thailand from Blue Dragon encounters, beachgoers experiencing burning pain after swimming should take the following steps:
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Exit the water immediately and seek help while calling the emergency hotline at 1669.
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Keep the injured person still and avoid rubbing the affected area, as movement can worsen venom exposure.
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Pour household vinegar (4–6% acidity) over the affected area continuously for at least 30 seconds. Do not rinse with fresh water, plain water, or alcohol, as this can worsen the sting.
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If symptoms do not improve, take the injured person to the nearest hospital without delay.
The DDC also advised the public and tourists to wear protective clothing while swimming, avoid swimming after rainfall, and look for vinegar stations along the beach. They should strictly follow posted warning signs and only swim in designated safe areas. If dead Blue Dragons or jellyfish are spotted along the shore, it is advised to avoid entering the water.
For more information, contact the Department of Disease Control hotline at 1422.
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