Hives, wheezing, shortness of breath and weakness are the general symptoms associated with anaphylaxis, therefore call 911 right away if you notice any such symptoms. Other systemic reactions to spider bites include leg cramps, leg numbness, headaches, pulse changes, exhaustion and more, they are all serious enough to determine one to call the doctor right away. There are several other varieties related to the black widow spider; they live in South Africa and Australia, and the major difference from the North American black one is of color: they are red and brown. Even in North America there are three different types of the black widow spider and their classification is made according to the geographical area where they live: there is the northern black widow, the southern black widow and the western black widow; thus the species is widely spread from the south of Canada to Mexico. A cold cloth pressed on the wound will reduced the swelling and the redness associated with spider bites in general. The immediate drug treatment of risky spider bites usually includes the administration of an anti-venom based on corticosteroids. The administration of specific medication can only be done by authorized medical personal and when the circumstances indicate a toxic venom exposure. Fortunately, the latter are far more numerous than the former, as poisonous spiders are spread only in certain globe areas, and sometimes they have warning features that sets them apart. In North America for instance, poisonous spider identification is a thumb rule for anyone living close to such creatures; there are not too many species of the kind, hence, once you learn how to set them apart you can relax and feel a lot safer. Nevertheless, it is worth mentioning that necrosis is very rare and almost accidental, since it appears in very special cases when the immune system of the victim is already impaired. Otherwise, the reactions to the hobo spider venom are pretty mild and temporary: pain, itching, redness and even swelling may appear, but these symptoms give in to local treatment. The only time when hobo spiders are really dangerous is when they are laying their eggs, particularly if they see you as a threat to their future siblings. It is also good to know that these creatures seldom inject any venom when they bite, which is why there is little health risk and discomfort. Even if hobo spiders live both on the American and the European continents, there is no difference in terms of physical specificity or venom composition.