If getting a tattoo is still a sign of rebellion, then a lot of Americans are rebels: 29% of adults now have at least one tattoo, up from 21% in 2012 and 16% in 2003, a recent Harris Poll found. Millennials are especially tat-happy: 47% of people ages 18 to 35 are inked, according to the poll.
But that increase in popularity has occurred despite what some doctors say are underappreciated and understudied risks. Among those urging caution is the Food and Drug Administration: In an update for consumers posted this month, the agency says it has received increasing reports of infections, allergic reactions and other adverse reactions linked to tattoos. The agency says it also is concerned about the unknown risks from long-term exposure to pigments and other ingredients in tattoo ink.
“Any time someone is going to inject something into their body, there are consequences,” says Linda Katz, director of the FDA’s Office of Cosmetics and Colors.  Consumers should know, she says, that not all of those consequences are clear.
Here’s what is known about some of the risks:
• Infection.  One percent to 5% of tattoo recipients get an infection, according to a review published in the medical journal Lancet in January. The infections can be bacterial, viral or fungal, and they can come from unsterile needles or contaminated ink. The FDA has asked manufacturers to recall contaminated inks about half a dozen times since 2004, Katz says. But it has no power to police tattoo parlors, which are regulated by a patchwork of state and local laws.
• Allergic and other immune reactions. It’s not known how common these are, says Marie Leger, a dermatologist at New York University Langone Medical Center. Leger and colleagues surveyed 300 tattooed people in New York’s Central Park and found that 6% reported rashes, itching or swelling persisting at least four months after a tattoo. In some cases, she says, a reaction might occur after multiple tattoos. “One of my patients had a red tattoo on her arm about 10 years before, then had another tattoo on her foot” with red ink, Leger says. Both tattoos became inflamed, scaly and itchy. She suspects the patient developed an allergy to red ink.
• Masking or worsening of skin conditions. Tattoos can trigger psoriasis flare-ups and make skin cancer harder to detect, Leger says.
• Long-term toxic effects. Here, little is known. Research is complicated by the fact that tattoo inks come in many different formulations, the Lancet review said. One concern is that the inks can break down in the body over time or when tattoos are removed by lasers.
But these concerns are being raised at a time when getting a tattoo is safer than ever, says John Montgomery, vice president of the Alliance of Professional Tattooists. Montgomery runs a tattoo studio in Redlands, Calif., and owns a tattoo ink manufacturing company.
“These pigments have been refined and they are cleaner and manufactured in a better way” than in the past, he says.
While tattoo artists are governed by different rules in different states and locales, all have a stake in safety, he says. “We really want to make sure people are healthy and safe. If people are healthy and safe, our businesses are going to thrive.”
Montgomery says concerns about theoretical long-term toxicity seem overblown. People who get tattoos, he says, still tend to “have a free-spirit kind of personality,” and “if they want a tattoo, they are going to get a tattoo. They are not going to worry about what’s going to happen 60 years down the road.”
Still, some will come to regret their tattoos and will face one more risk: the cost of removal. “It usually costs over $1,000 to have tattoo removed” over multiple laser sessions, and it can cost much more for large tattoos, says Jared Jagdeo, an assistant professor of dermatology at the University of California-Davis.
Tattoos “can be beautiful and interesting,” Leger says, “but people need to understand there are risks involved.”
Here are some things consumers can do to reduce risks and respond to problems:
• Make sure your tattoo artist complies with state and local laws. The National Conference of State Legislatures maintains a list of state laws online. Check with your local or county health department for additional rules.
• Treat a new tattoo like any open wound to prevent infection and scarring. That means covering it with a bandage the first day and moisturizing and cleaning the area properly until full healing occurs, usually in two to four weeks. It’s also crucial to protect the tattoo from the sun.