People have been getting tattooed for so long — at least 5000 years — that we can reasonably conclude that tattoos fulfill a primal human need, fused with the skin to indicate status, belonging, self-expression, or even as good luck charms to invite healing. More recently associated primarily with the shady domains of criminals and sailors, there's nonetheless a powerful secret history of tattoos among the highest echelons of society, including British royals and members of parliament. And still, tattoos induce stigma, which is incidentally the actual Latin word for them.
If you're inked or thinking about getting a tattoo, you probably won't be able to escape the impression some members of society have of the art as "dirty". Perhaps because I'm interested in tattoos, YouTube has thrown up some interesting videos about the supposed medical risks of tattoos, including one particularly disturbing one made by a Christian who considers tattoos sinful that shows how they supposedly cause tumors to grow all over your skin in a matter of years.
Are Tattoos Carcinogenic?
Despite recent scare stories all over the news triggered by European Union proposals to ban certain substances in tattoo inks  any clear link between cancer and tattoos is currently unproven . Though the proposed ban can only serve the health and safety of the tattooed population, ethical tattoo artists have been aware of the risks of certain inks for a long time, and purchase tattoo pigments with their clients' safety in mind.
Does he think, as a tattoo artist and tattooed person, that tattoos cause cancer? "Stress causes cancer," he believes. "And it's true that our body endures physical stress when we get tattooed." On the other hand, those writing alarmist articles about the dangers of tattoos are probably doing so via the internet. Many of them are glued to their smart phones 24/7, the radiation of which may contribute to health problems including cancer, while eating genetically modified foods which may be unsafe too, Voja adds. "We all lead stressful lives today, and as long as your artist isn't using truly poisonous inks — which exist — and you don't get tattooed every day, nothing will happen to you." (The scientific jury is still out, meanwhile, on whether stress truly contributes to your odds of developing cancer. )
Allergies To Tattoo Pigment
"Red ink used to be particularly well known for its ability to induce skin reactions and allergies," Voja recognizes and science confirms , though newer formulations have reduced that risk. "That has all changed now," he says, "thanks to a booming market that offers you the choice of many, many different inks".
It is clear that certain "metals, colorants and preservatives", some of which are known to be "extreme allergens" are present in some tattoo inks, a Danish paper concludes, adding that known allergens should be prohibited while further research needs to be conducted into other possible triggers. Meanwhile, the true number of people who experience allergic reactions or other immune responses to tattoo pigments are unknown, and if you do have a reaction, you may assume it to be permanent though it may well clear itself up over time. 
Having Blood Drawn As A Heavily Tattooed Person
Tattoos do not affect the process of having blood drawn in any way except that it can make finding a vein harder — something that can present a challenge for a more inexperienced phlebotomist but not one who really knows what they are doing. As a heavily tattooed person, this may mean that you end up with the best phlebotomist on the block, something that can never be a bad thing.
Does Having Tattoos Affect MRI Scans?
Certain tattoo inks, especially those contain iron oxide, can indeed create an electromagnetic reaction that leads to burn-like skin reactions, studies confirm. Large tattoos and designs that "display loops, large circular objects, or multiple adjacent points" are especially likely to cause issues, and if this is you, you should be offered cold compress treatment pre-emptively before undergoing an MRI scan. You should also, however, rest assured that such a reaction, if it does occur, is temporary. 
Which Medical Conditions Mean You Shouldn't Get Tattooed?
Though the CDC acknowledges that it is possible to contract HIV from tattooing, it adds that "there are no known cases in the United States of anyone getting HIV this way".  Reputable tattoo artists should essentially treat any client as though they may be HIV positive or carriers of other blood-borne diseases, and HIV isn't in itself a reason not to get tattooed. If you are HIV positive, you should still always be transparent about your status and choose a studio that is comfortable tattooing you — of which there are plenty. Like at the dentist, they may, however, ask that you book the last appointment of the day.
Patients with congenital heart disease may be at an increased risk of infective endocarditis if they are tattooed , and should carefully weigh the pros and cons of body art with their doctors before even considering a tattoo. Diabetes may likewise pose a risk, if it is not well-controlled, since it can delay healing and increase the risk of infection in the process. Diabetes does not, however, automatically mean you shouldn't be tattooed, and people with medical conditions including diabetes can indeed consider a tattoo as a permanent medical alert "bracelet". 
Tattoos — like so many other things that are part of modern life — indeed come with the minor potential of more serious complications. Is that a risk you are willing to take on? This is a question everyone will have to answer for themselves. Those who decide to get inked should know, however, that many of the potential medical risks of being tattooed can be mitigated by choosing a reputable tattoo studio that has modern health and safety measures in place, as well as using pigments that have your health and safety in mind. As the customer, you, too, play an important role in preventing complications, by closely following tattoo aftercare instructions provided by your artist.