alcohol "thins the blood?"

Yesterday, a friend of mine said she was going to have another tattoo done. During the conversation she said “A tattoo artist won’t give you a tattoo if you’re drunk because alcohol thins the blood”. My thinking was that a tattoo artist won’t give you a tattoo while you’re drunk because a biker who under the influence asked you to put “I love Richard Simmons” on his arm might come back the next day and kick your butt if you comply with his request. When I said “How does alcohol ‘thin’ the blood?” she said “I don’t know but it makes the bleeding slower to stop”. I’m not a doctor but this didn’t sound very convincing to me.

I tried a search in old GQ threads but I didn’t see anything that seemed to answer this question. I read EB:
Encyclopaedia Britannica: alcohol consumption - Physiological and psychological effects of alcohol
But I don’t think the EB article answers the question either. So I turn to the SDMB denizens. What’s the straight dope?

It is conceivable that someone who has been drinking excessively, and for a long time, may have “thin blood”. Specifically, alcohol in excess can cause a lowering of the blood platelets (those ‘cells’ in the blood that help make a clot). This can happen because alcohol is toxic to the bone marrow where the platelets are made. The effect is readily reversible upon cessation of drinking.

In the long term, alcohol in excess can also lead to cirrhosis. Cirrhosis does tend to cause “thin blood”, but that’s not something that’s gonna be reversed by abstaining for a day or two. It’s basically irreversible.

It was only from a movie, but when I watched Suicide Kings they said something about it. They basically said that alcohol damages the liver which produces vitamin K which helps blood clotting.

Obviously, I have no medical qualifications either, so take this with a grain of salt.

Both alcohol and aspirin are mild anticoagulants (aspirin moreso than alcohol) - they dont physically “thin the blood” per se (IANAD), but they make bleeding harder to stop.

It’s also ethically … something that many tattoo artists don’t want to get involved with … for many reasons

Aspirin, yes. But alcohol? Reference please.

If tattoo artists really refused clients who were drunk, many of the world’s tattoos would not exist. The tattoo in “Margaritaville” is not an isolated example. I won’t weigh in on the blood-thinning question, but I know several folks whose tattoo decisions were made while sloshed.

No site, but I thought alcohol was a vasodialator (meaning that in increases the size of your blood vessels). That’s why it’s a bad idea to consume alcohol then go into cold temperatures - the alcohol dialates your blood vessels and increases heat loss.


It’s just something I’ve “known”, but a quick google search turns up


Another: Dawns Tattooing FAQ’s Safe Tattooing

Another source, albeit a bit anecdotal: my brother is a tatoo artist. I have seen him turn many people away because they were drinking. His explanantion is about the same as those above.

Im not sure about the alcohol, however the water in the drink sure can thin the blood.

I suppose that if you drink alcohol, you are also drinking along with it a lot of water which thins the blood. No one drinks pure alcohol, you know?

jrishaw: Thanks! Good reference.
You know, at the risk of sounding self-serving, I don’t think the acute anticoagulant effect of alcohol (like that cited in the Nature article) is very well known by docs. I honestly can’t recall it ever being mentioned during the, literally, scores of rounds and sessions I’ve attended regarding alcohol. These have involved hundreds of docs, students, etc. Thanks for pointing it out.

handy: By your logic, drinking pure distilled water is even more potent at thinning the blood than alcoholic beverages.

Ditto for me, KG. Don’t remember running across info on the acute effect of alcohol on platelets at all, even in the articles touting the cardiovascular benefits of one drink a day. Hmmm…must be a conspiracy of the aspirin manufacturers!

During Spring Break a few years back, the guy in the room next door went to get his nipple pieced (ouch!). The piercer was apparently able to tell he had been drinking heavily the night before (as opposed to moderately drinking) because he bled profusely when the pierce was made. And he kept leaking for the next couple days, but only after midnight when he’d been drinking for several hours already. Sure seemed to thin his blood, from my observations.

I would think that drinking alcohol would make the blood “thicker”. Since alcohol is a diuretic, the kidneys process and pass more water than is ingested[sup]1[/sup]. This would decrease the total volume of the blood, while retaining all the solids like blood cells, and the blood gets thicker.
[sup]1[/sup]Columbia University College of P & S Complete Home Medical Guide

Thank you all for your comments, and especially jrishaw for the citation from Nature.

Meephead, it’s true tattooing sites mention not to get tattooed when drunk, but I wasn’t sure if they were just repeating an “urban legend” that had no foundation.

Fear Itself, that was almost exactly the reasoning I used when I was trying to tell my friend that her theory of alcohol “thinning the blood” sounded wrong. Apparently, I was the one in error.

“By your logic, drinking pure distilled water is even more potent at thinning the blood than
alcoholic beverages.”

Water thins the blood period. How do you think your blood gets water in it? What do you think makes it thin enough in the first place? Yep, water. Therefore, too much water = too thin.

No. Actually, too much water = too much urine.

And even if your kidneys couldn’t pee out the excess water intake, your blood would still clot normally. In the context of this thread (and in general parlance), “thin blood” means blood that is less likely to clot.

Well as the mod said, a search of the web for ‘alcohol thins the blood’ has numberous web sites with info:
“BOOZE, Please give me a break, just because you’re father got
drunk for his tattoo in 1952 doesn’t mean it was a good idea. All
it does is give you booze balls, and if you need that to get
tattooed you shouldn’t be getting tattooed to begin with. When
you’re drunk you’re more likely to pass out, get sick, or make a
lousy choice of designs. It also causes you to lose all your
muscle tone which makes it harder to tattoo, it makes you bleed
more (Alcohol thins your blood) which makes it harder to tattoo,
and drunks STINK. If you think you’ll get an artists best work
when they have to hold their breath to tattoo you because of the
booze stench oozing for your pores you’re WRONG.” (

"14.While some use alcohol or aspirin to reduce pain, these can cause blood thinning and prolong bleeding if a follicle is
accidentally damaged during treatment. "

" Water
taken internally, cools the body, thins the blood, makes the kidney’s smile because their work load is actually decreased with
increased water intake."
Is it any wonder the mods say to search the net first?

Water doesn’t thin the blood in the sense of making the platelets less coagulating. A humongous amount of water may, for a very short time, increase the volume of blood so, proportionately, there are less platelets. However, the platelets clotting abilities are not affected. Moreover, the body tries to stay in homeostasis. It has mechanisms to maintain the proper ionic concentrations, etc. In less than hours, the excess water in the blood will be diverted to the kidneys; wherefrom, it will be, to used the technical term, pissed out.

Something similar happens to those athletes participating in long distance events encompassing several hours who drink only water. That may dilute the sodium content, a vital electrolyte, resulting in hyponatremia. People have died from that because before it could be reversed, the necessary neural activities were interrupted, as sodium is essential for neural transmission.

I should have noted, in my last post, that an athlete sweats out sodium, so it is not just a matter of having less sodium proportionately, but having less sodium period. Whereas the platelets are not diminished by drinking water, just diluted.