(CNN) -- An estimated 25% of people in the United States have a permanent tattoo, making it one of the most popular forms of body art. But those colorful etchings of birds and symbols can sometimes cause ugly and painful skin problems. A new study suggests that 10% of people who get inked experience infections, itching and other adverse reactions, sometimes lasting more than four months.
Researchers at New York University asked people in Central Park whether they had a tattoo, and if so, whether they had any reactions after getting tattooed that they thought were out of the ordinary, such as redness and scarring.
Out of the 300 people the researchers surveyed, 31 (10.3%) said they developed abnormal reactions. In 4% of these cases, the reactions, including pain, itching and infection, went away within four months. Some required antibiotics. The other 6% had itching, scaly skin and swelling around the tattoo site that lasted for more than four months.
"I was totally surprised by these numbers," said Dr. Marie C. Leger, assistant professor of dermatology at NYU Langone Medical Center and lead author of the study, which was published Thursday in the journal Contact Dermatitis. "I see patients with complaints about their tattoos, but I didn't have any idea how common it was," Leger added.
However, as Leger pointed out, it is not clear if the numbers in her study are representative of this large subset of the population. Researchers need to study bigger groups of people, and follow up with physical exams and biopsies to confirm and diagnose their conditions, she said.
Leger got motivated to study tattoo complications after treating a patient who developed itching and raised, scaly skin around only the red parts of a tattoo on her arm. She had the first tattoo for years but the symptoms started after getting a more recent tattoo on her foot. In addition to the problems at the tattoo site, she developed a rash over her whole body. "It was like her body decided after being exposed to red dye more than once, that it just didn't like it," Leger said.
There are many questions over what is causing these undesirable side effects. Leger said she suspects that allergic reactions to the dyes, especially red dye, are responsible for some of the chronic reactions lasting more than four months.
In Leger's small survey, chronic reactions were more likely in people who had more variety of colors, and red seemed to be particular problematic. Other small studies have also reported lesions associated with red tattoos.
If chronic problems do arise, it is possible to remove the tattoo, Leger said. However in the case of the patient who inspired the current study, the tattoos covered too much of her body to easily excise.
Many of the problems that the survey captured, both the acute and chronic reactions, "don't have anything to do with the tattoo parlor or the artist," Leger stressed. "It's not anybody's fault, it's body meets ink and what happens," she said.
Nevertheless, some of the acute problems that occur in the days and weeks after body and ink meet can be avoided. For example, people should make sure to clean the tattoo site to reduce infection risk, and follow other instructions from the tattoo artist, Leger said. The study found that acute problems were more likely among people who had many tattoos and tattoos that covered a large part of their body.
If any signs of an infection develop, such as warmth, swelling and drainage at the tattoo, people should go to an urgent care clinic or get some other medical help immediately, Leger said.
Although the numbers in the New York survey seem high, they may underestimate the complications linked with getting tatted. "Some of the skin reactions may be very subtle and require a dermatologist to diagnose exactly what it is," said Dr. Jared Jagdeo, assistant professor of dermatology at UC Davis, who was not involved in the current research. Problems with tattoos on the back or other out-of-sight areas may go unnoticed, too, he added.
Studies in Europe have found similar, and in some cases higher, rates of tattoo complications.
"The findings [of the current study] highlight the importance of educating the general public prior to tattooing," Jagdeo said. "Anytime you introduce a foreign substance into the body, in this case the skin, there is the potential for adverse events [such as] infection or something more serious like an allergic reaction," he said.
However, tattooing is a lot safer now that many states and cities inspect tattoo parlors to make sure they are using safe practices and equipment such as single-use needles, Jagdeo said.
There are no federal regulations on tattoo ink. "I think the composition of dyes is an area that will be looked at in the future at the state and potentially federal level," Jagdeo said. "This study is very important to bring attention to this important topic," he said.
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