Fever and infection
It's not fully understood why certain cancers cause fevers and others don't. It's thought that some cancers may produce things like toxins that cause fever.
Having cancer or treatment for cancer can weaken your immune system. This makes it more likely that you will pick up an infection and develop a fever.
Apart from your cancer treatment, there are a number of other reasons why you might get a fever when you have cancer.
Last reviewed: 07 Apr 2026
Next review due: 06 Apr 2029
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