The following quote is from Reef Keeping, online magazine and concerns the Lionfish.
The info can be accessed at the following website:
http://www.reefkeeping.com/issues/2002-11/fm/feature/index.php
Lionfish Sting... What To Do
“If a lionfish or scorpionfish ever stings you, the very first thing to do is immerse the wound site in hot, non-scalding water (110-113°F) for 20 to 30 minutes, or until the pain subsides. According to Michaels (1998), applying rapid heat using a hair dryer will also work. The key point is heat; lionfish venom contains many heat labile proteins, and heat will denature these venom proteins, preventing them from spreading in the bloodstream and decreasing the severity of their effects. Do not use boiling hot water; the burn resulting from boiling water will often be worse than the lionfish sting. The most frequent symptoms of a lionfish sting are pain and swelling. However, a few people may have an allergic reaction to lionfish venom and should be cautious if the pain and swelling get worse over a few hours. .”