Tattoo Ink Side Effects Linked to Inflammation, Immune-Cell Death: Study

Researchers warn that tattoo ink can also enhance or decrease the effects of certain vaccines, including those for the prevention of COVID-19 and the flu.

Data from a new study suggests ink from tattoos can migrate into the lymph nodes and disrupt the body’s immune system.

Tattoos have become increasingly popular in the U.S., with about 32% of Americans now having at least one and 22% having multiple. During the process, the skin is repeatedly punctured so the ink can settle beneath the surface. While generally considered safe, tattoo ink can still cause side effects, including infections and changes in the lymph nodes.

According to new findings published in the journal PNAS on November 25, researchers have also found that tattoo ink can settle into the lymph nodes for months, kill immune cells, cause chronic inflammation, and alter how the body responds to vaccines.

The data appears to reinforce a separate Swedish study published last year that concluded tattoo ink causes inflammation in the lymph nodes, increasing a person’s risk of developing lymphoma. Prior research has also warned tattoo ink side effects may include cancers and bacterial infections.

A 2018 study found nearly 50% of all tattoo inks on the U.S. market contain harmful bacteria. As a result, several tattoo ink recalls have been announced in recent years due to bacterial contamination. The issue became so prevalent the U.S. Food and Drug Administration (FDA) issued new guidance for manufacturers and distributors in October 2024.

For the new study, researchers from the University della Svizzera Italiana in Switzerland investigated the relationship between tattoo ink and the immune system.

Led by Dr. Arianna Capucetti, the team’s data analysis showed tattoo ink pigments can settle into the lymph nodes within minutes of application, and may remain there for months. Researchers said that for some, the ink could potentially stay in the lymph nodes for the rest of their lives.

Mouse studies showed that tattoo ink caused immune-cell death and chronic inflammation, which Capucetti noted would be expected to produce a long-term inflammatory response in humans as well.

Tattoo Ink Vaccine Impacts

The team also found that injecting a COVID-19 mRNA vaccine into tattooed skin produced a much weaker antibody response compared to injections in non-tattooed skin.

Researchers then injected an inactive flu vaccine into tattooed skin and found the body produced a stronger immune response. Researchers said this may be because the inflammation caused by the tattoo ink amplified the effects of the vaccine.

Since the study was conducted in mice, the researchers cautioned that the same effects may not occur in humans. However, they said the findings are important for shaping tattoo ink policy, which is far less regulated than medical products, and for helping the public better understand the potential health risks associated with tattoos.

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