Tattoos are more popular than ever, especially among younger generations. But as the trend grows, scientists warn there may be more happening beneath the skin than most people realize. A new study from Switzerland’s Institute for Research in Biomedicine, published on November 25, suggests tattoo ink can alter how the immune system responds to disease.
Researchers focused on the three most common colors—black, red, and green—and found that pigment doesn’t just stay on the skin. Instead, it travels through the body and can accumulate in lymph nodes for years. Because immune cells struggle to break down the ink, inflammation may occur, potentially weakening defenses against certain illnesses.
Tests in mice showed a reduced immune response to COVID-19 vaccines after tattooing—though reactions to another type of flu vaccine appeared stronger. Scientists caution that the findings need to be confirmed through human studies and different vaccines. Meanwhile, global health experts are also investigating possible long-term risks, including links to lymphomas and other cancers.
Today, tattoos are largely aesthetic—a way to mark memories, identity, or simply decorate the body. And with up to 40% of adults under 40 in Europe and the US already inked, the safety conversation is only becoming more relevant. So, which countries have the most tattoos among their population? Click on to find out.