Surgery can make you more likely to get an infection because it makes a break in the body’s natural defences, such as the skin or membranes (layers of tissue, like the lining of your mouth). If you have surgery to remove your spleen then you’ll have a permanently reduced immune system and will have to take antibiotics regularly to protect yourself from infection.
Radiotherapy can have a mild, temporary effect on your immune system but it probably won’t affect you immunity too much, unless you’ve had total body irradiation (TBI). TBI is only given to people who are about to have a bone marrow transplant. During TBI all the bone marrow in the body gets a dose of radiation which lowers the production of white blood cells and means you’ll be at risk of infection for a while.
Chemotherapy can have a big effect on your immune system and might reduce your body’s defence against infection for some months (both during and after treatment). This is because chemo lowers the production of white blood cells by the bone marrow. People on chemo are particularly at risk of picking up infections from about 7–10 days after the start of chemo. It lasts for about a week, maybe longer. This is the time when you have to take even more care of yourself to try and protect yourself from infections.
