Answer
Feb 02, 2026 - 01:09 PM
Yes. KEYTRUDA (pembrolizumab) can cause serious lung problems. The most important one is immune-mediated pneumonitis, which is inflammation of the lungs and can resemble pneumonia. In clinical data, immune-mediated pneumonitis occurred in about 3.4% of patients receiving KEYTRUDA and, rarely, was fatal.
Pneumonia itself has also been reported as a serious adverse reaction in some KEYTRUDA clinical trials, although pneumonia is usually caused by an infection rather than the immune reaction responsible for pneumonitis.
Contact the oncology team promptly for new or worsening cough, shortness of breath, chest pain, or fever while taking KEYTRUDA. These symptoms need evaluation because pneumonitis, pneumonia, cancer-related lung problems, and other causes can look similar. Treatment for suspected KEYTRUDA-related pneumonitis may require holding KEYTRUDA and using corticosteroids depending on severity.
