The use of meat tenderizer has earned mention in the medical literature.
One should not rub the area briskly or wash the area with freshwater.
Both of these can stimulate further discharge of the jellyfishes
nematocyts and worsening of the condition.  If you must wash the area off,
use sea water.  Vinegar (5% acetic acid) is felt by some to be the
treatment of choice.  It too will inactive the proteins in the toxin.  It
needs to be applied for at least 30 minutes.
  There are some jellyfish evenomations that may defy "home remedies".
The box jellyfish, Chironex fleckeri, comes to mind.  It may rank as one
of the most toxic animals on the planet, and a small sting may lead to
death. Possibly some of our members in Australia, where this creature
hails from, may be able to provide additional deatils regarding Chironex.

Charlie
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Charlie Sturm, Jr
Research Associate - Section of Invertebrate Zoology
                     Carnegie Museum of Natural History, Pittsburgh, PA
Assistant Professor - Family Medicine

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