The causes of left foot big toe pain are as follows: first, bunion: bunion, the distal end of the first metatarsal bone, that is, the head of the toe bone will be protruding, often rubbing against the inside of the upper surface of the shoe, and over time there will be a bunion, which is manifested in the first metatarsophalangeal joint pain. Second, gouty arthritis: long-term high-purine diet, such as seafood intake or a large number of alcohol consumption, easy to cause uric acid crystals in the first metatarsophalangeal joint accumulation, often appear in the big toe acute pain, accompanied by redness and swelling of the situation. Third, acute metatarsophalangeal arthritis attack: mostly seen in middle-aged and old people, there is often joint degeneration, cartilage loss, in the case of cold invasion, easy to cause arthritis attack, manifested in the metatarsophalangeal joints of the red, swollen, accompanied by obvious pain.