Painful pressure on the nail cap of the big toe may be related to the following reasons: 1. There may be injuries in the nail groove and around the nail bed. This is most commonly caused by bunion or tight shoes, which leads to long-term extrusion and friction, thus causing injuries in the above areas. It is also common for the patient’s toenail to be inadvertently lifted by a foreign object, resulting in a certain degree of damage to the nail bed.2. It may be caused by infections around the toenail, such as serious fungal infections around the nails, that is, gray nails, which may cause damage to the toenail, and lead to pain. In addition, if there is trauma, it is very easy to secondary bacterial infection, and lead to severe pain. 3, this condition may also be caused by bleeding in the nail bed. Bleeding in this area is often caused by over-exertive activities or when the foot is stepped on by other people, which results in internal bleeding and pain. 4. It is also common to see lesions in the toe bone, such as toe bone fracture or osteomyelitis, which may also cause the above symptoms.