Pemetrexed Injection is a chemotherapy drug used to treat certain types of cancer, such as lung, mesothelioma, and ovarian cancers. It works by blocking enzymes that cancer cells need to grow and divide. It is usually given by injection into a vein. It is usually given in combination with other chemotherapy drugs. Side effects may include nausea, vomiting, hair loss, fatigue, and an increased risk of infection.