Tattoo ink doesn’t just sit inertly in the skin. New research shows it moves rapidly into the lymphatic system, where it can persist for months, kill immune cells, and even disrupt how the body responds to vaccines.
Scientists in Switzerland used a mouse model to trace what happens after tattooing. Pigments drained into nearby lymph nodes within minutes and continued to accumulate for two months, triggering immune-cell death and sustained inflammation.
The ink also weakened the antibody response to Pfizer Inc. and BioNTech SE’s Covid vaccine when the shot was administered in tattooed skin. In contrast, the same inflammation appeared to boost responses to an inactivated flu vaccine.
The findings, published this week in the Proceedings of the National Academy of Sciences, sharpen a public-health question as tattooing becomes mainstream. A 2023 Pew Research survey estimated that 32% of U.S. adults have at least one tattoo, and 22% have multiple.
With billions spent on tattoos each year, the authors at Università della Svizzera italiana in Bellinzona say the results point to a need for tougher toxicology testing and stricter oversight of tattoo-ink ingredients, which face far looser regulation than medical products.
“This work represents the most extensive study to date regarding the effect of tattoo ink on the immune response and raises serious health concerns associated with the tattooing practice,” the researchers said. “Our work underscores the need for further research to inform public health policies and regulatory frameworks regarding the safety of tattoo inks.”
The study doesn’t show whether similar immune effects occur in people — that hasn’t been tested. But it flags clear risks. Pigments have long been documented in human lymph nodes, and the mouse findings mirror what’s been observed in both humans and primates.
A 2024 Swedish study of almost 12,000 people found tattooed individuals had a 21% higher risk of malignant lymphoma than those without ink, with the strongest associations appearing in the first two years after getting a tattoo and again more than a decade later. The elevated risk spanned major lymphoma types, both aggressive forms such as diffuse large B-cell lymphoma and slower-growing ones like follicular lymphoma.
A Danish twin study published in January reported similar patterns. Tattooed participants had higher risks of skin cancers — including melanoma and squamous cell carcinoma — as well as lymphoma, with hazards rising further for tattoos larger than a palm. In one arm of the study, large tattoos were linked to a 2.7-fold higher hazard of lymphoma and more than double the risk of skin cancer.
Researchers in both countries say the accumulating evidence merits deeper investigation, especially as pigments such as carbon black, polycyclic aromatic hydrocarbons and azo dyes are known to migrate to lymph nodes and remain there for years.
Gale writes for Bloomberg.
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