The most common Casodex side effects are back pain, breast tenderness, constipation, diarrhea, dizziness, headache, hot flashes, impotence, insomnia, nausea, and etc. If you are experiencing any severe side effects such as chest pain, easy bruising or bleeding, jaundice, muscle weakness, numbness, signs of infections, stomach pain, tiredness, urination problem, vision changes, and serious symptoms of any allergic reaction (e.g., difficult breathing; hives; itching; rash; swelling), please inform your doctor immediately.