Radiotherapy can cause nausea, tiredness and diarrhoea. However, these are not severe and can be helped or prevented by drugs. Chemotherapy can cause loss of appetite, tiredness, ringing in the ears, shortness of breath, nausea, vomiting, mouth ulcers, infections, kidney problems and hair loss. The higher the dosage, the more severe the side effects. Patients on high-dose chemotherapy are monitored carefully by their doctors.