1.Avoid applying vinegar to the affected sting. There are conflicting reports about the effectiveness of vinegar. Some sources say to apply vinegar to any jellyfish wound. Other sources say only to apply vinegar to stings from the box jellyfish. (If you're stung by a box jelly, however, remember to seek immediate treatment instead of trying to treat the sting yourself.) But new findings are suggesting that vinegar may actually make matters worse