For example, a suddenly enlarged, scary-looking big toe is probably gout. Gout is a form of arthritis (also called 'gouty arthritis') that's usually caused by too much uric acid, a natural substance. The built-up uric acid forms needlelike crystals, especially where there is low body temperatures. The coolest part of the body, farthest from the heart, happens to be the big toe. "Three-fourths of the time, you wake up with a red-hot swollen toe joint as the first presentation of gout," says Dr. Andersen.