1. When the blue bottles come in contact with humans, they react in exactly the same way as they would when faced with danger, and they sting us. Blue bottle jellyfish stings are known to be extremely painful. The sting can cause an extremely painful rash which doesn't subside for at least an hour after the sting. While the sting in itself does not cause any major effects in the human body, a sensitive individual who is prone to allergies can have an extreme reaction to the toxins in the blue bottle's venom. An allergic reaction can lead to fever, heart and lung failure and may even lead to death, even though it is extremely rare. Additionally, if a person has received multiple stings, he may be at risk of very severe pain and will require immediate medical attention. It is also important to remember that detaches tentacles of a blue bottle are also capable to delivering a sting for a few hours after detachment.<br />The riskiest of all these is the box jellyfish of the cubozoans class. Box jellyfish are mostly found in Australia and are known to have very dangerous venom that can cause an immediate collapse of the cardiovascular, respiratory, and neuromuscular causing paralysis and killing within minutes. It's therefore quiet true that a jellyfish sting can kill you. Once you get stung by the box jellyfish, you will need immediate administration of anti-venom which of course will undo the effects of the poison. Whether you're stuck by a killing sting or a non fatal sting, it's advisable to rid yourself off all tentacles on the skin using forceps or gloves. DO NOT use your bare hands as they might stick again on your hands and continue spreading the venom in your blood. Applying vinegar will also disable all stingers and make the symptoms less severe. If a jellyfish stings you on the mouth, face, eyes, genitalia, etc, or you become very ill after a jellyfish sting, i.e. experience difficulty in inhalation or swallowing, or even develop some very severe pain because of a jellyfish sting, it's highly advisable to seek emergency medical attention immediately. Remember this is venom entering your body and the more it stays in you the more it reacts with different body parts, which may eventually cause death<br />