If you know someone who's likely to get a tattoo, tell him (or her) the US Centers for Disease Control and Prevention says to make sure it's done by a professional and not just a friend.
In a recent meta-analysis, CDC researchers found that tattoos from non-professionals - friends, family members, prison cell-mates - carried a risk of hepatitis C infection.
On the other hand, there was no evidence that tattoos done by professionals carried a hepatitis C risk.
In the US, there are roughly 18 000 new hepatitis C infections each year, most of which occur when people share tainted needles or syringes.
But in almost 20% of acute hepatitis C infections, the person has no known risk factor, said Dr Rania A. Tohme, a medical epidemiologist at the CDC who led the new study.
Given that – and the popularity of tattoos – there have been concerns that the body art could be a risk factor for hepatitis C.
Tattoos a risk for hepatitis C
Based on the new findings, it's the tattoos from non-pros that consumers should beware, according to Dr Tohme.
The data, published online in Clinical Infectious Diseases, are from several dozen studies published since 1994. In general, people who had tattoos done by non-professionals faced a hepatitis C risk that was two to four times higher than average.
Prison tattoos are a particular concern, Dr Tohme's team writes, because tattooing is so common, and many prisoners have other risk factors for hepatitis C. Outbreaks of the infection have been linked to tattooing among prisoners.
But no US outbreaks have been tied to professional tattoo parlours. "To this date, there has been no evidence that tattoos and piercing performed in professional parlours in the United States have been implicated in transmission of hepatitis C virus," Dr Tohme said.
(Amy Norton, Reuters Health, February)
Piercing and tattoos