One of the silliest topics that I’ve covered over the past 10+ years of writing for SBM, at least among the ones that I didn’t make up myself, was the claim that tattoos might boost the immune system and even make recipients healthier in general, but only if you get a bunch of ’em. Not that I have anything against tattoos, as long as appropriate safety measures are in place. Being tattooless, I have no skin in this game except for a desire for a better informed public.

In the innocent days of October of 2019, I first discussed the work of University of Alabama anthropologist Christopher Lynn on the potential relationship between getting some ink and “boosted” immune function that had been published in the American Journal of Biology in 2016 and again in 2019. This paper had resulted in some news articles that left a lot to be desired and I took them all to task. Lynn thanked me for the analysis on Twitter but accused me of sullying the good name of medical anthropology. In reality, I merely sullied the good name of Professor Lynn and called into question why an anthropologist was doing terrible medical research seemingly without any input from actual experts in immunology.

History, like Ka, is a wheel.

Lynn had initially set out to show that people who had received multiple tattoos over time have a more robust immune response to a new tattoo than people who are tattoo naive, a hypothesis based on pure conjecture that awkwardly compared getting a tattoo to going to the gym. The idea was that this repetitive stress could train the body to fight off infection more successfully. His initial 2016 study was small, with only 29 subjects, and involved measuring cortisol and secretory IgA (SIgA) in saliva both before and after participants got a tattoo. The decision to use these as surrogate markers of global immune function was based more on convenience rather than good science, however.

SIgA, as well as the small amount of serum IgA floating around in our bloodstream, is a component of our immune system’s response to microbial pathogens and does play a role in protecting us from some infections. SIgA coats the mucous membranes lining our respiratory, GI, and genitourinary tracts and works by attaching to antigens on the surface of microbial pathogens to help prevent penetration through these membranes where they could gain access to the bloodstream and other tissues. It’s also easy to measure because a blood draw isn’t necessary.

IgA isn’t that important, however, and it isn’t a helpful surrogate for general immune function. Millions of people have a selective IgA deficiency to varying degrees and it is by far the most common primary immunodeficiency. But most people who don’t have enough IgA are asymptomatic and diagnosed incidentally. Again, while some people do present with an unusual number of infections, most people with low or absent IgA do not get sick more often than people who are just lousy with the stuff.

As I explained back in 2019, relying on salivary SIgA levels isn’t helpful:

A lot of people are deficient in the stuff, but because there are many redundant immune functions the vast majority, around 90% in fact, don’t have more infections. And in the 10% of IgA-deficient patients who do develop more infections, they don’t tend to be more severe. And this is over a lifetime of having no IgA. So the notion that transient changes in SIgA levels in response to acute stress might alter your risk of catching a cold is not well supported.

Lynn’s initial study found that undergoing placement of a tattoo resulted in a decrease in salivary SIgA, but this response appeared to be more robust in subjects getting their first tattoo. Experienced subjects were still found to have lowered SIgA, just less so. But all the measured levels were within normal parameters for SIgA and, as I hope I’ve made clear, none of this matters anyway. There was, and still remains, no plausible scientific reason to think that these changes, even if the observed pattern wasn’t just random noise, would have any clinically relevance. These results don’t add anything to our understanding of the immune system or even the body’s response to tattoos.

The cortisol levels were obtained in order to show an association between stress and SIgA levels, with the assumption that acute stress (higher salivary cortisol) would be associated with decreased immune system function (lower SIgA). There is a nugget of plausibility to this as it is well recognized that stress, primarily chronic stress, absolutely does play a role in many negative health outcomes, decreased immune function definitely being one of them. Lynn’s overarching hypothesis, however, was that getting multiple tattoos, essentially brief stressors spread out over time rather than chronic constant stress, somehow trains the body to be more resistant to stress in general, which would result in a “primed” immune system better capable of responding to invasion by microbial pathogens.

And though they did appear to find an inverse relationship between cortisol and SIgA, it is almost certainly random noise, or lab error, because numerous studies in animals and human subjects have consistently found that acute stress transiently increases SIgA levels in saliva. Chronic stress is associated with lower levels, but chronic stress impairs immune function through mechanisms more varied and significant than specifically just a reduction in SIgA. Again, SIgA levels have never been accepted as a marker of overall immune function but have been used as a marker of stress.

The bottom line is that the results of Lynn’s study were almost certainly spurious and couldn’t have answered his question anyway. It was, to put it bluntly, garbage. His approach needed to change.

Narrator: “His approach would not change.”

That was 2016. In 2019, when I wrote my original post, Lynn had published a follow-up study in an attempt to replicate his meaningless findings. This time, 25 subjects were recruited and pre and post tattoo saliva samples were collected for measuring SIgA, cortisol, and an inflammatory marker. As I wrote in my previous post, the results did not shed much light on the situation:

So in this small study, they found that some of the subjects had higher levels of SIgA after getting a tattoo. Remember, in the previous study they all had decreased levels. This supports the notion that it’s all just random noise rather than that the immune system was somehow boosted. The claim that elevated SIgA levels, even if directly caused by the tattoo, would play a role in non-mucosal surface healing or general health goes against the basic scientific understanding of what these antibodies actually do in our bodies.

Lynn would claim that the new study bolstered his belief that tattoos have immune system benefits and even added improved wound healing and general health to the list. His language in an article he wrote at the time came very close to comparing tattoos to vaccinations:

Tattooing seems to exert a priming effect: That’s what biologists call it when naive immune cells are exposed to their specific antigen and differentiate into antibodies that remain in the bloodstream for many years. Each tattoo prepares the body to respond to the next.

In that 2019 article, Lynn hinted at the future by mentioning an ongoing study involving 50 subjects. Nothing of much importance happened in the world for a while after that except for Taylor Swift becoming the embodiment of Satan. Fast forward to 2024 when, last week, I randomly had an unprovoked memory of this topic and decided to see what had become of Professor Lynn and his research into the health benefits of tattoos.

I found that in April of 2023, Parade Magazine had published an article on the subject for no apparent reason that I could find, as it only mentions the 2016 and 2019 studies I’ve already discussed. It is apparent, however, that Lynn had continued to expand on his belief system despite the lack of scientific plausibility or any new supporting research, and more clearly compared tattoos with vaccines:

The dermal injury of getting the tattoo and the pigment left in the skin—in both cases, we are purposefully injuring ourselves, but in a way that is analogous to exercise,” Dr. Lynn says. “We are tearing muscles to build muscles. We are stimulating the immune system to have a more robust reaction.”

Dr. Lynn says the research also draws comparisons between tattoos and vaccinations. “[With vaccines], we introduce a challenge, cause our immune system to turn on, and when the immune system turns back off, it remains somewhat vigilant,” Dr. Lynn says. “It creates new antibodies in circulation at a higher rate. Our immune system is adaptive. It interacts with our appraisal of stress.”

“What we see with novel or first tattoos is that cortisol, a stress hormone, goes up, while immunoglobulin A goes down,” says Dr. Lynn. “For people with relatively more tattoo experience [these reactions vary].”

(Clay here. Again, many studies have previously and since found that acute stress raises SIgA levels. The varied reactions that he found were likely due to lab error or random noise in the data and do not represent any actual trends in human physiology.)

In a way, you can think of tattoos as “training” the immune system. “One of the things that training the immune system is useful for is dealing with the topsy-turvy up and down of life,” says Dr. Lynn. “Even if the tattoo lasts a long time and is putting stress on the body, the immune response is happening immediately and throughout the experience. That suggests there is a priming effect [between tattoos and the immune system].”

Thankfully Lynn doesn’t actually go so far as to claim that getting a tattoo is truly equivalent to a vaccine when it comes to preventing disease:

“I would never say anything like that,” Dr. Lynn says. “What we are saying is that there is an effect. Is it clinically significant? Not by itself. It is an extra influence on our health and well-being. What I usually say is, ‘If you want to be healthy, there are a hundred ways under the sun to be healthy. Tattooing is part of the lifestyle…here are additional benefits.'”

But even this milquetoast support of potential medical benefits from tattooing isn’t reasonable. Later in the article, and to his credit, Lynn clearly states that tattoos are not something he recommends to people with autoimmune disease to “strengthen the immune system” and mentions that his wife has lupus. We don’t generally think of these conditions as being caused by a weakened immune system, but rather one that is confused and causing damage from friendly fire, though treatment of these ailments often does consists of medications that do suppress the immune system. This adds to my concern that Lynn is way out of his depth here and should be relying on actual experts for help, which brings us to the unfortunate involvement of an actual expert. Sigh.

In the Parade Magazine article, there are several quotes from Dr. Sharon Nachman, who is the Chief of the Division of Pediatric Infectious Disease at Stony Brook Children’s Hospital, Vice Dean for Research at the Renaissance School of Medicine at Stony Brook, and she directs their Office of Clinical Trials. So she is an actual expert and should have no problem seeing just how bad these two studies are. She should be highly skeptical of the entire premise that tattoos improve immune function.

That isn’t what happened, and I am honestly baffled. She says the following in regards to the 2019 study:

“It’s a great paper,” said Dr. Sharon Nachman, MD, the chief of the division of pediatric infectious diseases at Stony Brook Children’s Hospital. “It looks at patients with a long history of tattoos. It looks at those who got tattoos versus those who didn’t. Did they have lower infections or rates of common illness? The answer is yes…as part of immune functioning, they were better able to handle infections.”

None of that happened. Neither the 2016 or 2019 study, and these two studies represented the totality of the literature on the subject of immune boosting tattoos at the time, did anything of the sort as I’ve explained in painful detail. So she either didn’t read the study, and perhaps regurgitated the take presented to her by the articles writer, or she was horribly misquoted. I truly hope that it was the latter, but frankly both are terrible.

In regards to people with autoimmune conditions getting tattoos in the hopes of seeing a benefit, she appropriately states that we don’t know if the risk outweighs the benefit, which seems to imply that there might be some benefit. She calls it an important scientific question and calls for more research. I disagree and I’m still confused as to how we got here. She does at least point out that tattoos should be done in a safe and hygienic fashion.

I was disappointed to learn that Lynn’s claims continues to be given an undeserved patina of academic legitimacy when I came across a September 2023 study. Sadly it is essentially just a rehash of the same flawed approach used in the first two experiments and used saliva samples left over from the 2019 study and a 2022 study that I believe is the one Lynn had referenced as ongoing back in 2019. 40 samples from subjects with with varying degrees of tattoo experience taken both before and after getting some fresh ink were included, only this time they focused on something called a bacteria killing activity (BKA) assay as a marker of overall immune function instead of SIgA.

Their results, as expected, were a mess. First off, the BKA assay is something that the 2nd author of the paper developed and is not a validated marker of general immune function. And there were problems with sample contamination that they just ignored. They also lost or didn’t have enough remaining saliva to perform the assay in a number of subjects. And what they found completely contradicted the earlier two (really 3 according to the discussion but I can’t access the 2022 study to see for myself) studies using SIgA, so they threw them under the bus and claimed that the BKA assay just works better. Convenient.

In fact, their failure to replicated the supposed immune suppression seen in tattoo naive subjects in this study completely undermines the entire hypothesis this was all based on. Acute stress is supposed to cause a transient insult that, with repeated exposures over time, teaches the body to be stronger like when Daniel-San learned karate by waxing Mr. Miyagi’s car. They also failed to find, using their unproven saliva assay, that subjects with more tattoo experience have a more robust immune system prior to getting the new tattoo. But they just forged ahead, cherry picking and nudging the goalposts a bit so that they could claim some degree of success:

We found that dermal stress of tattooing results in increased innate immune activity that is influenced by previous tattoo experience, supporting the model of tattooing as a phenotypic gambit. Tattooing may therefore enhance evolutionary fitness signals.

Garbage all the way down.

Of note, there was a March 2023 article in The Atlantic entitled “Tattoos Do Odd Things to the Immune System”. Unfortunately, I was unable to access it to see if this topic was covered with more appropriate skepticism, but I’m not hopeful considering the title. If anyone can get a hold of it, please let me know in the comments.



  • Clay Jones, M.D. is a pediatrician and has been a regular contributor to the Science-Based Medicine blog since 2012. He primarily cares for healthy newborns and hospitalized children, and devotes his full time to educating pediatric residents and medical students. Dr. Jones first became aware of and interested in pseudoscience in medicine while completing his pediatric residency at Vanderbilt Children’s Hospital twenty years ago and has since focused his efforts on teaching the application of critical thinking and scientific skepticism. Dr. Jones has no conflicts of interest to disclose and no ties to the pharmaceutical industry. He can be found on Twitter as @SBMPediatrics.

Posted by Clay Jones

Clay Jones, M.D. is a pediatrician and has been a regular contributor to the Science-Based Medicine blog since 2012. He primarily cares for healthy newborns and hospitalized children, and devotes his full time to educating pediatric residents and medical students. Dr. Jones first became aware of and interested in pseudoscience in medicine while completing his pediatric residency at Vanderbilt Children’s Hospital twenty years ago and has since focused his efforts on teaching the application of critical thinking and scientific skepticism. Dr. Jones has no conflicts of interest to disclose and no ties to the pharmaceutical industry. He can be found on Twitter as @SBMPediatrics.