For medicinal purposes only

A reader writes:

Hey, I get cheese sweats too!

While we're on the subject, when I drink alcohol, especially spirits, it makes me feel warm, starting in the stomach and moving out. How "real" is this effect? I presume it's not actually changing my core body temperature, because that'd make a shot of Jack Daniels a life-threatening event. What's actually going on?


Alcohol indeed does not change your core temperature, but it genuinely can change the distribution of heat in your body. Ethanol is a vasodilator; it causes the smooth muscle around blood vessels to relax and let more blood through. If the ambient temperature is cool, your peripheral blood vessels will naturally be somewhat constricted, reducing blood flow to your extremities; when the vessels dilate, more warm blood flows through those outer vessels, the tissue there thus warms up, and you feel warmer. Because some parts of you genuinely are.

In extreme situations, this can be dangerous. The reason why the body constricts outer blood vessels when it's cold is specifically to avoid losing valuable heat via the extremities. Knock back some Scotch when you're hypothermic and it'll make you feel better (because of both the vasodilatory warming effect, and the psychoactive effects of the alcohol), but you'll also accelerate heat loss and actually make the situation worse.

(For this reason, although St. Bernards are used for alpine rescue, they've never had little barrels of brandy hanging around their necks. Oh, and the whole vasodilator thing also made the traditional use of alcohol as a snake-bite remedy actually a really bad idea.)

In non-life-threatening situations, like when you're cold but not dangerously so and come in to sit by the fire in the ski lodge, alcohol may help you warm up by increasing blood flow through the extremities that're now being warmed by the fire. More prosaically, an alcoholic nightcap can help with that vicious circle where you get into bed with cold feet and your feet stay cold, because cold feet don't have the blood flow to produce much heat for the bedclothes to retain.

Psycho Science is a regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

4 Responses to “For medicinal purposes only”

  1. michaelshewitt Says:

    Actually, I believe snake venom travels through the body via the lymph system; I have no idea if vasodilators have an effect upon it.

    • RichVR Says:

      No, it's blood borne.

      • Bern Says:

        Well, that's not what every senior first-aid instructor has told me for the past 20 years...

        The compression bandages they teach you (here in Australia, at least) to apply in case of snake bite are specifically intended to reduce flow in the lymphatic system, while *avoiding* blocking blood flow to avoid necrosis.
        Good ol' Wikipedia suggests that it may be effective (though there's little evidence either way) against venoms that contain neurotoxins, which covers just about all of the dangerous snakes here in Australia (family elapidae).
        The article also says that it's not appropriate treatment for a viper bite. But, you know, it appears that Australia is one of the few parts of the world that doesn't have any snakes of the family viperidae.

  2. yetanotherdan Says:

    I'm sure I have also heard that marijuana has an opposite effect, in that it causes an increased blood flow to the internal organs, making you feel colder externally. This was the explanation for the 'whitey' where someone who has drunk alcohol (and reduced internal blood flow) and then smoked gets a sudden rush of blood which causes them to look pale and often throw up due to rush of blood to the stomach

    The converse situation (smoking first, then drinking) can actually allow you to drink more as the increased blood flow helps you to process the alcohol faster (again, stoner hearsay - YMMV).

    That's why I've also always advocated Swiss St Bernards with a special-cigar holder rather than brandy barrel...

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