Patients undergoing chemotherapy for cancer are prone to life-threatening infections. Prompt antibiotic use saves lives, but the best way to manage fevers during infection is not known. Paracetamol is often used to lower fever and improve patient comfort, but might delay recovery from infection. We wish to determine whether paracetamol should be used during infections after chemotherapy. Patients will be randomly assigned to receive paracetamol or a placebo. We will measure response to antibiotics, quality of life and length of hospital stay. Before the full trial, a feasibility study is needed to ensure paracetamol reduces temperature, to see if placebo treatment is acceptable, to decide if a sensitive measure of bloodstream bacteria is a useful marker of infection, and to ensure we can recruit sufficient patients. If this feasibility study is successful the main trial will show whether paracetamol is effective and safe during infections after chemotherapy.