Hyperventilation syndrome or hypocalcemia is the most common cause of hand stiffness when crying. People will unconsciously breathe faster, gasp more frequently, and change their breath a lot after being overly emotional, angry, or crying, resulting in a large amount of carbon dioxide exhalation in the body, which lowers the partial pressure of carbon dioxide in the plasma and increases the pH value, leading to respiratory alkalosis. Hyperventilation syndrome often manifests as labored breathing, chest tightness, pressure, choking, tachycardia, numbness at the ends of the limbs and face, twitching of the hands and feet in the shape of chicken claws, and even dizziness, headache, and impaired consciousness. Once this happens, the patient needs to be calmed down by reassuring the patient, instructed to breathe slowly, assisted breathing is recommended to reduce excessive carbon dioxide exhalation by slowing down the breathing rate, or a mask can be given to restrict ventilation so that the patient can breathe in his own exhaled carbon dioxide to correct hypocapnia, or a paper tube can be chosen for the patient to breathe inside the tube without special handling. The patient will slowly resolve. If the above measures are not effective beyond the ability to handle the patient on the spot, seek medical attention.