Is it safe for a patient doing chemo get a tattoo?

The reason that doctors often warn against getting a tattoo -- or doing anything else that's an infection risk-- while undergoing chemotherapy is that chemo drugs lower cancer patients' white blood cell count, and white blood cells are the ones that fight infection. It's not that the tattoo is going to interfere with cancer treatment exactly, but an infection can be very dangerous when the body is immune compromised.

Most tattoo artists take precautions to make the procedure safe and infection-free, but when it comes to needles piercing the skin, there is going to be an infection risk.

If your family member really wants to get a tattoo, and can't wait until chemotherapy's completed, it would be best if they discussed it with the oncologist.