A Facebook warning claiming that a black line down the centre of your nail can indicate melanoma has gone viral.

The post, which you can see below, says that a client had this issue with one of her nails and when investigated, the woman in question received a melanoma diagnosis. According to the Facebook post, the customer asked for a colour dark enough to cover the stripe on her nails which she had previously been told was the result of a calcium deficiency and later, a blood blister. It is important to point out that this is often the case with changes in nails but at the same time, 'dark stripes' on nails are something to take very seriously, as in some cases, this can be a sign of subungual melanoma. Melanoma Ireland explains that "subungual melanoma is melanoma of the nail affecting the tissue beneath the nail base, also known as the nail matrix. It is the region from where the nail forms and grows". An excerpt from the Facebook warning reads:

"Please pay attention to abnormalities in your nail beds!! Odd changes in your nails can very likely be nothing to worry about! But sometimes it is an indication of a very serious disease. And please keep an eye on the nail beds---toes and fingers----of your elderly loved ones and your loved ones that aren't physically able to notice changes in the nail beds! Early diagnosis can make all the difference in the world!!! "Sometimes it is an indication of a very serious disease. And please keep an eye on the nail beds---toes and fingers----of your elderly loved ones and your loved ones that aren't physically able to notice changes in the nail beds! Early diagnosis can make all the difference in the world!!!".

It was shared by a woman named Lisa Harrison Williams but it's not clear if she's the technician who saw the woman's nail or if she just shared the information in an effort to spread awareness. It has gone massively viral nonetheless and has been shared by numerous publications across the world.