Treatment for a jellyfish sting includes rinsing the area with seawater or a solution of salt water. With some types of stings, soaking the affected area in vinegar mixed with an equal amount of water helps to relieve the pain. Scraping the remaining tentacles with a credit card is also useful. Avoid rinsing the sting with fresh water, recommends KidsHealth.
In some people, jellyfish stings cause severe reactions, including anaphylactic shock. Such individuals need immediate emergency care, including an ephedrine injection. If there are signs of a serious reaction, it is essential to call emergency services. According to Mayo Clinic, the individual could require cardiopulmonary resuscitation due to the sting. Stings from the box jellyfish often require antivenin and pain medication.
According to MedlinePlus, the prognosis for an individual suffering a jellyfish sting depends on the type of jellyfish. Portuguese man-of-war stings are rarely deadly, even though they are painful. Sea wasp stings sometimes cause death within minutes. Box jellyfish cause death in as many as 20 percent of their victims, depending on locale.
KidsHealth advises swimming in guarded beaches to reduce the chances of a sting. It recommends watching for flyers, signs or a purple flag, which indicates dangerous marine life in the area. When swimming in an area where jellyfish are sometimes present, families can prepare by carrying a container of vinegar to the beach.