The effectiveness of drugs known as immune checkpoint inhibitors in the treatment of cancer is increasingly well understood. The use of immunotherapy is associated with a number of unique side effects, since its mechanism of action is different from that of traditional cytotoxic chemotherapy. Immunotherapy causes a sterile pneumonitis picture similar to pneumonia as pulmonary system toxicity. Early recognition and rapid intervention of pulmonary symptoms are the main goals in the management of immunotherapy-induced pulmonary toxicity. In patients treated with immunotherapy, pulmonary toxicity should be considered in the complaints of dyspnea and cough, especially if it is new onset. If pneumonitis is suspected in a patient treated with immunotherapy, it is necessary to determine the severity first. Mild pneumonitis can be followed closely, and immunosuppression is usually required along with discontinuation of immunotherapy treatment in patients with moderate-to-severe pneumonitis. The mainstay of treatment for pneumonitis is corticosteroid. After recovery, corticosteroid should be tapered gradually over 4–6 weeks, and immunotherapy treatment delayed until the daily corticosteroid dose equals 10 mg oral prednisone or less. Empirical antibiotic therapy should also be considered. In cases that do not respond to steroids within 48–72 h, additional immunosuppressants should be initiated. There is a high risk of developing immune-related adverse effects with re-administration of immunotherapy, and these adverse effects can sometimes be fatal. In patients with pneumonitis rechallenged with immune checkpoint inhibitors especially, anti–PD-L1, half of the patients experienced recurrence or new immune-related adverse event. This decision should be taken on a patient basis by carefully evaluating the risk-benefit ratios.