A tattoo that isn't properly cared for can get infected. Infected skin will be red, warm, and painful. It may also leak pus. If the equipment or ink your artist used was contaminated, you could get a bloodborne infection, such as hepatitis B, hepatitis C, tetanus, or HIV.
A 2018 study that looked at the risk of infection with tattoos found that 6-10% of adults who had a tattoo experienced infectious complications. If a tattoo causes severe symptoms or pain that lasts for more than a few days, it can be a sign that there is an infection that needs medical attention.