Tattoo aficionados know they should only frequent parlors where things are clean and the artist uses sterile tools. But dangers may lurk elsewhere -- new studies show the ink itself could be contaminated.

Dozens of skin rashes and infections have been linked to some pre-mixed ink made with non-sterile water that may contain mycobacterium chelonae, a type of tuberculosis-related skin bacteria.

Symptoms typically surface within a week or two after being tattooed and include a possibly painful or itchy rash and tiny bumps that resemble an allergic reaction. Left untreated, the bacteria can lead to a variety of serious ailments, and in people with compromised immune systems, it can even be fatal.

What's worse, getting rid of it is no easy task -- it can often require at least six months of treatment.

The water-based bacteria typically poses no problems for healthy individuals, but when it's injected under the skin during the tattooing process, it bypasses many of body’s natural defenses and can grow.

Experts believe the current outbreaks were caused by gray ink that's made by diluting black ink with water and is often used to create smudgy, shaded effects around tattoos. And because inks don’t have to be tested by the FDA for safety or purity, the dangerous bacteria went undetected.

Doctors advise people to keep a close eye on new tattoos, and to see a doctor if a rash shows up within the first two weeks after being inked.

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