Pain on the side of the chest near the armpit may be due to pleurisy, trauma, intercostal neuralgia and other conditions. 1. Pleurisy: The pleura of the dirty layer and the pleura of the wall layer will rub against each other along with respiration, thus producing pain. The pain is more pronounced due to the high mobility of the lung tissue on the chest side of the axilla. Tuberculous pleurisy can also be accompanied by low-grade fever, night sweats and other systemic symptoms. 2. Trauma: local soft tissue injury or rib fracture caused by collision or extrusion, which is manifested as local pain, aggravated by coughing or changing position, and localized skin lesions or bruises. 3. Intercostal neuralgia: mostly manifested as pain distributed along the intercostal nerves, which is semi-annular, stabbing or burning pain. Axillary chest pain can also be seen in other diseases, it is recommended that patients seek medical attention in time, so as not to miss the condition.