2 dermatologists told us why you should never, ever tattoo over your moles

• Changes in moles can be the first clue of melanoma and other forms of skin cancer.
• Two dermatologists say they don't recommend tattooing over moles, especially with blue or black ink.

When it comes to diagnosing skin cancer, looking for changes in moles and performing self-examinations are some of the best ways to stay safe.

But the early signs aren't always easy to spot — especially if you have tattoos.

"I'd say 80-90% of our patients have tattoos and at least 30% have more than one," said Dr. Alexander Witkowski, an assistant professor of dermatology at the OHSU School of Medicine, who recently diagnosed the world's smallest skin cancer.

Witkowski and his wife Dr. Joanna Ludzik, who collaborated with him on the discovery and is also an assistant professor of dermatology at OHSU, spoke to Insider about how to get inked safely.

Check to see if you have any concerning areas first

In general, Dr. Ludzik recommends patients perform self-skin examinations every 3-4 months, but especially over the places they plan to get tattooed.

She also suggested visiting a dermatologist right before getting tattooed to make sure any potential problem areas — like areas with a large number of moles or other skin conditions — are in the clear for getting inked.

Get tattoos around your moles

If you really want a tattoo in an area where you have moles or beauty marks, Witkowski highly recommended getting tattoos around the moles, and keeping about a 1-millimeter distance between the ink and the spot.

That way, if the mole grows or changes shape, you'll be able to notice a difference because the tattoo itself will look different.

If you already have tattoos over moles, skin checkups can take longer

Because color changes are one of the signs of melanoma, ink — particularly blue or black ink — can make it difficult to tell if the colors are part of the tattoo or a sign of developing skin cancer.

As a result, Witkowski said he sometimes needs to biopsy ultimately benign lesions out of precaution.

It also means that he and Ludzik take longer to perform skin checkups on tattooed patients. "We're just extra thorough with patients who have large surface area tattoos," he said.