Hi, BCG given for bladder cancer has its own side effect. About 1 in 2 people have flu like symptoms for 24 to 48 hours after each treatment. You should tell about this to his treating doctor in your next appointment. There is also a very small chance that some of the TB could get into his system and give him TB symptoms such as fever, joint pain, vomiting cough, skin rashes.These effects only happens to fewer than 1 person in every 100 who has this treatment.It is important that you tell your doctor straight away if he has any of these symptoms or have a high temperature for more than 48 hours. He may need treatment with anti TB drugs and should not wait until his next appointment to let his doctor know. Do consider a positive feedback as a credit to my work. Let me know if you have any further questions.