The most common side effects include vomiting, diarrhea, anorexia (loss of appetite), fluid retention, fatigue, headache, rash, hypocalcemia (low calcium level), and decreases in blood counts. Other possible side effects may include nausea, joint pain, muscle aches, generalized pain, abdominal pain, and fever. Rare side effects may include QTc prolongation (heart beat changes), pulmonary edema (fluid around the lungs), difficulty breathing, cough, hemorrhage, gastrointestinal bleeding, pneumonia, cardiac effusion (fluid in the sac surrounding the heart), and cardiac failure. Temodar has been well tolerated by both adults and children with the most common toxicity being mild myelosuppression. Other, less likely, potential toxicities include nausea and vomiting, constipation, headache, alopecia, rash, burning sensation of skin, esophagitis, pain, diarrhea, lethargy, hepatotoxicity, anorexia, fatigue and hyperglycemia. As in the case with many anti-cancer drugs, Temodar may be carcinogenic. Rats given Temodar have developed breast cancer.