Pemetrexed injection IP 500 mg is an antifolate drug used to treat certain types of lung cancer and mesothelioma. Pemetrexed injection IP 500 mg is approved by the U.S. Food and Drug Administration (FDA) for the treatment of malignant pleural mesothelioma and non-small cell lung cancer (NSCLC). Pemetrexed injection IP 500 mg may be used alone or in combination with other chemotherapy drugs, depending on the type and stage of cancer being treated. Common side effects of pemetrexed injection IP 500 mg may include fatigue, nausea, vomiting, mouth sores, loss of appetite, hair loss, and diarrhea.