I recently posted about another recall and withdrawal of tattoo inks from the market — in part due to excess benzisothiazolinone, but in some cases due to containing formaldehyde and lead too. (See the post on Facebook here.)
Reader Tammy asked whether a long-standing tattoo could suddenly cause new reactions, and I thought this was such a good question, it deserved a fuller answer than the one I gave her there.
I looked into it a little, and it seems the quick answer is … Yes, long-standing tattoos can cause allergic contact dermatitis or other inflammatory skin reactions months or even years on.
Here’s the more detailed answer …
Tattoo Reactions
Isothiazolinone preservatives should be limited to 10mg per 1kg in tattoo inks, but research suggests that many inks are non-compliant with this guideline. And although on this site we’re mostly interested in the isothiazolinones, other ingredients in tattoos can cause problems as well — other preservatives, azo dyes, and heavy metal-based pigments, for instance.
One interesting phenomenon I’ve come across in this Brazilian paper from 2024 and which accounts for many delayed reactions to tattoos is haptenization. As the paper says: “Haptenization occurs when UV light affects the pigments and alters their chemical composition, making them recognizable as foreign substances and triggering an immune response.” In simpler terms, sun exposure can break down tattoo ink chemicals in your skin into smaller chemical molecules over time, and you eventually become sensitised or react to these breakdown molecules. This appears to affect red inks and red-inked areas of skin the most.
According to another study from the Journal of Cosmetic Dermatology in 2021, the second most common tattoo complications after red-ink allergy are chronic inflammatory black tattoo reactions (CIBTR). The average time for onset of this particular condition is around 4 years, but one case study experienced onset of symptoms after 17.5 years. These reactions are often associated with the gathering of tiny black pigment particles in the skin layers, which the body can’t remove, causing a long-term immune response.
Metals in colours can cause reactions too — cadmium in yellow, cobalt in blue, chromium in green, and the most allergenic metal, nickel, when present in low quantities in inks as an impurity (it can also be introduced into the skin through the tattooing needle during the procedure — as can chromium). The immune system does not always react straight away when the tattoo is placed on the skin. Instead, the body can become gradually sensitized to the metal allergens or pigments over an extended period. Once sensitization happens, a reaction can appear to come out of nowhere years later, potentially triggered by sun exposure, local skin trauma, illness, or changes in the immune system function.
While it is obviously possible to be sensitised to the isothiazolinones through tattooing, the preservatives as organic molecules are highly unlikely to linger in the skin or in the system to sensitise or trigger reactions years later. Studies show that preservatives, being water soluble, are quickly absorbed by the system and excreted in urine.
If you were tattooed a long time ago, long before you developed sensitivity to the isothiazolinones, the culprit is likely to have been from an alternative source, possibly through cosmetics or household detergents or paint or an industrial exposure.
If you do find yourself reacting to a tattoo years after you had it placed on your skin, it’s likely to be due to haptenization, CIBTR or a delayed reaction triggered by lowered immunity / ill health, injury to the skin, or the effect of the sun — but not the dreaded isothiazolinones.
Stay well, people, and don’t forget your sunscreen!