Numbing Cream and Tattooing: Why Your Prep Work Changes Everything
By the time an artist reapplies numbing cream during a tattoo, the skin has already been washed, shaved, degreased and punctured. The barrier that normally limits absorption has been altered at several points. That is the part I think gets overlooked when people focus only on the percentage printed on the tube.
Adding more anesthetic during the session means applying it under different conditions from the untouched skin it started on. Some artists also work over the product without cleaning it off first.
I formulate topical products, including liposomal numbing preparations. Some of the prep described here is my own practice, especially the shave gel. I've cited the research behind the absorption mechanisms and identified the healing observations that haven't been studied.
These are drugs, not cosmetics
The common topical anesthetics are lidocaine, prilocaine, benzocaine and tetracaine, usually just called "caines."
They are dangerous when misused. The FDA issued a public health advisory in 2009 after two women died using topical anesthetics before laser hair removal. Poison centres logged 579 lidocaine cases in 2023, of which 34 were severe and four were fatal.
Three lines from that FDA advisory are worth reading twice. Do not apply these products to irritated or broken skin. Do not wrap treated skin. And when skin temperature rises, the amount reaching the bloodstream becomes unpredictable.
In my experience, numbing products became much more common in tattooing over the last ten to fifteen years. I haven't found long-term outcome data covering repeated application during tattoo sessions. That limits what anyone can claim about a lifetime of use.
What each prep step does to the barrier
Your skin's barrier is the stratum corneum. It works because of lipids arranged in an ordered, tightly packed structure that most drugs cannot cross. Strip those lipids, disorder the packing, or remove the layer, and it stops being a barrier.
Here is the sequence I use. Washing and shaving are familiar shop practices; the shave gel and stencil technique are particular to how I work.
I start with green soap. Its surfactants lift oils, and the alcohol-containing concentrate is meant to be diluted. That first wash is already changing the surface, even though the applied alcohol concentration is lower than the bottle's.
For shaving, I use a gel I make with aloe, carbomer, TEA, propylene glycol and enough mentholatum to cool it. Most artists I've worked around shave with green soap instead.
The reason is razor burn. A dry or poorly lubricated shave drags the blade, and that irritation causes more tattoo problems than artists tend to credit. Rashes, bumps, and folliculitis, which is inflammation of the hair follicles that a blade can both provoke and seed. Tattooing over inflamed follicles is a bad starting point. A proper shave gel reduces drag and cuts that risk.
The trade-off is that two of those ingredients are textbook penetration enhancers.
Propylene glycol is one of the most widely used chemical penetration enhancers in transdermal drug delivery. It sits in the lipid headgroup region, occupies the lipid–water hydrogen bonding sites, and increases lipid tail disorder in a concentration-dependent way. It is in drug patches specifically because it opens the barrier.
Menthol does the same job differently. It is widely used clinically as a penetration enhancer, disrupting the ordered lipid packing of the stratum corneum. At low concentrations it relaxes and fluidises the layer; at around 5% it seriously damages the structure and destroys barrier function outright. Mine carries only enough to cool, far below that, but the direction of the effect is the same.
The menthol is part of my sequence. It shouldn't be attributed to an artist who shaves with green soap alone.
Shaving also removes some stratum corneum mechanically. Researchers use tape-stripping to study that kind of barrier disruption; a razor changes the surface too.
The alcohol wipe changes the barrier again. I use 91% alcohol in my sequence. Molecular dynamics research shows that ethanol perturbs the skin barrier by extracting lipids, including free fatty acids from the bilayer. Ethanol and isopropanol are both described as promoters of transepidermal transport through changes to the epidermal lipid matrix.
One nuance that works in our favour. Alcohol's enhancing effect is not linear with strength. Permeation studies found it peaking around 70% and falling off above that, because concentrated alcohol dehydrates the skin. So a 91% wipe is a thorough degreaser but probably a weaker penetration enhancer than a diluted one would be.
And a correction to a belief I used to hold. The ice-cold feeling is evaporative cooling, not a readout of lipid removal. I use it as a timing cue because it reliably means I have been at it long enough. It is not a measurement, and wiping harder to chase a colder feeling just strips more barrier for nothing.
Ethyl or isopropyl, if you want to be particular about it
I prefer ethyl alcohol over isopropyl, and there are two reasons.
The first is sourcing. Isopropyl alcohol is a petrochemical product, made industrially by hydrating propylene, which comes from cracking fossil fuel feedstocks. Ethanol for most commercial uses is fermented from grain or sugar. If you would rather not wipe a petroleum derivative across broken skin all day, that is a reasonable position to hold.
The second reason is better, and it comes out of the same comparative study cited above. When several alcohols were tested as vehicles for skin permeation, isopropanol was found to be the best enhancer of the group. Best at pushing things through the skin.
For my prep wipe, that makes ethanol worth considering. The comparison concerns its behavior on skin. The source of an alcohol alone doesn't establish how safe or suitable the finished product is.
Stencil adhesive adds another formulation to the shaved, degreased skin. Many products contain propylene glycol, so a penetration enhancer can be present before the first needle puncture.
In my stencil technique, I lay the paper while the gel is tacky. I lightly dampen a paper towel with alcohol and wipe over the paper until the purple begins showing through, then fan it until the paper is white and dry. I peel slowly because it can grip hard enough to tear. That describes my method, rather than instructions that override a product manufacturer's directions.
That multiplies adhesion on any generic stencil gel. It works because you briefly resolvate the dye and carrier so they move into the skin instead of sitting on it. No wait afterwards; it is already in.
Then the needles puncture that prepared skin, and cleaning continues for the rest of the session.
Now add numbing cream
Compare the skin before step one with the skin by the time it is sore enough that someone reaches for a numbing agent.
Lipids lifted by surfactant, then extracted by alcohol. Stratum corneum shaved. Barrier chemically disordered by a penetration enhancer in the stencil product, and in my case a second one in the shave gel. The layer then perforated outright and washed repeatedly for the rest of the session.
The FDA's 4% limit for over-the-counter lidocaine assumes normal, intact skin.
None of this is normal, intact skin.
And enhancers are not selective. They work by disordering the barrier, so they increase permeability to whatever is sitting on it, not only to the active you intended. One review of the field notes plainly that enhanced skin penetration is not always a desirable outcome.
Nobody has measured what this sequence does to systemic absorption during a tattoo. The honest position is that the dose reaching the bloodstream is unknown and very likely higher than the product label contemplates.
The concentration trap
Look at what the FDA has had to act on. Warning letters went to companies selling 40% lidocaine gel and 29.9% cream against an over-the-counter limit of 4%. Ten times the legal concentration, marketed openly to artists and clients.
Increasing the drug concentration adds to the amount available for absorption. It doesn't solve the uncertainty about what gets through prepared or broken skin.
Delivery matters as well as concentration. A liposomal formulation can change how an anesthetic is delivered, but a lower percentage alone doesn't establish safety during tattooing. The actual formulation, amount used and condition of the skin still need evaluating.
Why stacking caines is restricted
Health departments restrict combining numbing agents, and the reason is better than most artists have been told.
Methemoglobinemia. Benzocaine, prilocaine and tetracaine oxidise haemoglobin into a form that cannot carry oxygen. Benzocaine is the strongest oxidiser of the group with a documented dose-response, and combining agents raises the risk further. The FDA estimated over 400 cases from benzocaine between February 2009 and October 2017.
The presentation is what makes it dangerous in a shop. The client goes grey-blue, not red or swollen. Cyanosis does not improve with oxygen, the blood runs chocolate brown, and a fingertip pulse oximeter reads low while arterial oxygen is actually normal. The monitor lies.
Small exposures are enough. One published case describes a previously healthy 33-year-old man admitted with fever, respiratory distress, cyanosis and acute haemolysis after self-medicating with tetracaine throat lozenges for a sore throat. Lozenges.
The epinephrine question
Mixing a caine with epinephrine is restricted separately, and the usual explanation for why is wrong.
Epinephrine is added to injected local anesthetics specifically to slow systemic absorption. Vasoconstriction keeps the drug local and extends the block. So the hazard is not that epinephrine drives caine toxicity.
The concerns I want to separate are epinephrine's own systemic effects and what prolonged vasoconstriction might mean for skin being tattooed.
Epinephrine toxicity in its own right. A case report documents a 33-year-old woman who developed systemic epinephrine toxicity, presenting as NSTEMI and lactic acidosis, after using a topical anesthetic gel containing lidocaine and epinephrine before a tattoo. The authors call it the first documented case of its kind and warn that it presents in the opposite direction from lidocaine toxicity, hyperadrenergic rather than hypotensive, so it gets misdiagnosed.
Duration of ischaemia. This part is my own reasoning, and I want it read that way. Restricting blood flow is not inherently harmful. Restricting it for hours while causing thousands of puncture wounds is a different matter. The skin goes pale and takes on a texture like cold turkey skin. Prolonged ischaemia alongside ongoing trauma is a reasonable mechanism for accelerated cell death, and what I associate with it is more plasma afterwards, longer healing, and sometimes a scarring pattern that looks almost marbleised, as though small chunks are missing.
I haven't found that pattern studied. It is an observation from watching tattoos heal, rather than a diagnosed cause or a research finding.
The numbing hangover. Also mine. Once the agent wears off, pain is often worse than an equivalent untreated tattoo and healing can be rougher. My reasoning is that dead tissue feeds bacteria and the body ends up handling both at once. Reactive hyperaemia after a vasoconstrictor wears off is established pharmacology; the rest is my inference.
What I think should happen
I would rather work with a medical director who reviews formulations, approves them for a compounding team, and holds the oversight. That is harder to arrange than it used to be, and the difficulty is appropriate. These are invasive products and the regulatory hurdles exist for a reason. A bactine-type product is one thing. Anything designed to cross the barrier is another.
I would want evidence that a formulation delivers the intended effect with an appropriate dose, alongside oversight of how it is used. Calling it safer needs more than a stronger numbing effect.
Clients should know what is being applied to their skin. Medical conditions and previous reactions can make that information especially important.
Practical notes
Check the actual concentration and the product's instructions before discussing its use with a client. Take shaving irritation seriously, and remember that reapplying onto broken skin changes the exposure. Wrapping the area or heating it can increase absorption. Clean off residual product before working over it.
Grey-blue skin, breathlessness or a concerning low oxygen reading can be signs of methemoglobinemia and require emergency help. Dizziness, ringing in the ears, a metallic taste and tingling around the mouth can be early signs of lidocaine toxicity. Those symptoms are reasons to stop and seek help, rather than push through the session.
Sources
A multiscale study of the penetration-enhancing mechanism of menthol (2019)
Percutaneous permeation enhancement by terpenes: mechanistic view (open access)
Penetration enhancement of topical formulations, Pharmaceutics (open access)
Lidocaine toxicity, StatPearls, NCBI Bookshelf
Benzocaine and lidocaine induced methemoglobinemia after bronchoscopy: a case report (open access)
FDA public health advisory (2009): improper use of skin numbing products can be deadly
FDA warning letters on over-the-counter topical pain relievers exceeding lidocaine limits (2024)
EMLA Cream prescribing information, US FDA
This article combines published research with my own working practice. The prep sequence, the shave gel and the two clinical impressions above are mine and are labelled as such. Nothing here is medical advice, and nothing here authorises anyone to compound or supply a drug product.
For how pigments behave once they are in skin, see do tattoo ink ingredients interact? For what is in stencil products specifically, see what's actually in stencil gel and transfer paper.
For tattoo work in Arlington, Texas, visit the booking page.
