Spiders are to be found everywhere and whilst most are poisonous only a few have mouths big enough to get you. Generally speaking, travelers only have to worry about finding dangerous spiders in the warm areas of the world. Again, get to a hospital as fast as you can for an anti venom. Bites should be treated as for snake bite.
Tarantulas can be found in southern Europe but these huge, hairy spiders are absolutely terrifying, their bites aren’t that bad.
The Fiddle back spider occurs in the USA and has a violin shape at the back of its head. Causes fever, chills, vomiting. Rarely fatal but can cause degeneration of the skin or lead to amputation if left untreated.
Black Widow Spiders are found in deserts across the world. Small and dark they have distinctive red, yellow or white markings on the abdomen. Their bites are very painful and can lay you out for a week with sweats and chills but are rarely fatal.
Funnel web spiders are large grey or brown spiders with chunky legs that you might find when traveling in Australia. They move around at night and these can kill. If you see webs in the shape of a funnel you’ll know to take care.