The pain behind the big toe can be seen in the 1st metatarsophalangeal arthritis or bunion deformity accompanied by bunionitis, which can be analyzed as follows:1. The 1st metatarsophalangeal arthritis is related to the high mobility and the damage of the joint, which will be accompanied by localized pressure pain, which will be alleviated by resting, and aggravated by activities. The joint space can be narrowed, the joint surface hardened, and osteomalacia can be seen on radiographs.2. Bunion pain is caused by bunion deformity, which leads to repeated friction between the medial side of the 1st metatarsal bone and the shoe, resulting in localized aseptic inflammation, which can cause pain in the bone, localized redness of the skin, and in severe cases, an increase in the temperature of the skin. It can be improved by reducing activities and applying topical medication, such as Xue Shan Jin Luo Han Pain Relief Coating and Diclofenac Diethylamine Gel.