Lionfish have venomous glands at the base of the fins. The spines can inflict intensely painful, burning and throbbing pain. Swelling can also occur at the site. Even after this type of fish dies, it can retain active venom for up to 48. This can be dangerous to handlers.
Soaking the area of the sting in hot water is recommended. Heat treatment in non-scalding hot water (up to 114° F/45° C) is widely recommended as effective initial treatment for lionfish, echinoderms, stingrays and other venomous spine injuries. This should be done after the visible spines are removed. Immersion is continued until the agonizing pain is relieved, usually a minimum of 30 minutes, and often up to 60-90 minutes. There is no anti-venom for lionfish stings. A local or regional anesthesia can also relieve pain.