Bottom line: Why do vampires need to suck blood? Is it their major source of nourishment? Is it a mystical or magic thing where the life force keeps them alive? Is it just a compulsion that they can't control, without the blood doing anything for them?

Just what is this whole "blood sucking" thing about?

I know you can't cover every mythos in depth, but I'm sure there's a lot in common from one to the next. While some may have more in depth explanations, I would also think a lot would be simple, like saying, "It's life force and they need it to keep functioning," or something like that. I'm not asking for a huge answer for every mythos, but since this is one of the points central to the entire vampire mythos, that certainly makes it a legitimate question, since it's really just accepted in almost any mythos, but rarely (if ever) explained.

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    Sorry, there's way too many vampire canons/mythos to be able to answer this conclusively. ALL of the possibilities you listed are present in some. You need to either ask for a full encyclopedic answer listing ALL needs from all canons, or restrict to specific canons Jan 12 '12 at 18:02
  • Or you can break it down and talk about one or two of the bigger mythos involved, or give big answers about the major ones (like classical ones) and very short comments about smaller ones. Or address only a major trend or two. There's lots of ways to cover this and I'm not expecting anyone to cover every single mythos.
    – Tango
    Jan 12 '12 at 18:06
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    If you're aiming at the canon of the mythological creature as a whole (as in, the written history regarding vampires), that's arguably not covered by the site (not really 'fiction' per se, but I'm not sure we've officially discussed what place mythology has). Jan 12 '12 at 18:12
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    Good grief! It's not an essay question on your SATs and I'm not sitting here grading it on some scale. I just want to know: Why do vampires suck blood? Is that not possible to answer?
    – Tango
    Jan 12 '12 at 18:14
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    @Tango - based on my admittedly limited knowledge of vampire related stuff, IMHO it is indeed impossible to answer fully, though I'll take a stab. Too many options. If you provide specific canon/mythos, that would be possible Jan 12 '12 at 18:18

The reason vampires are associated with blood drinking is that "vampire" means "blood sucker" and porphyria was a common illness. Porphyria is a disease that causes irrational behavior, a phobia of light, paleness, and a desire to ingest blood. A common cure in the 1800s was a cup of cow's blood from a butcher to avoid attacking people. The folklore of vampires coming from the grave to drink blood derives from when a corpse is exhumed, and due to gasses built up in the body pushes blood out of the orifices, usually the nose and mouth. With an outbreak of a disease that causes erratic behavior, and corpses with blood around the mouth people, came to the assumption that the dead had risen to feed. Vampires and werewolves

Porphyria has been suggested as an explanation for the origin of vampire and werewolf legends, based upon certain perceived similarities between the condition and the folklore. In January 1964, L. Illis' 1963 paper, "On Porphyria and the Aetiology of Werwolves", was published in Proceedings of the Royal Society of Medicine. Later, Nancy Garden argued for a connection between porphyria and the vampire belief in her 1973 book, Vampires. In 1985, biochemist David Dolphin's paper for the American Association for the Advancement of Science, "Porphyria, Vampires, and Werewolves: The Aetiology of European Metamorphosis Legends", gained widespread media coverage, thus popularizing the idea. http://en.m.wikipedia.org/wiki/Porphyria

Origins of Belief While the majority of vampire scholars focus on the cultural roots of vampire lore, some historians have looked to physical origins. There is no scientific evidence of actual vampires, but there are a number of real medical conditions that might result in vampiric behavior or appearance. One of the most interesting "vampire diseases" is porphyria. Porphyria is a rare disease characterized by irregularities in production of heme, an iron-rich pigment in blood. People with the more severe forms of porphyria are highly sensitive to sunlight, experience severe abdominal pain and may suffer from acute delirium. One possible treatment for porphyria in the past might have been to drink blood, to correct the imbalance in the body (though there's no clear evidence of this). Some porphyria sufferers do have reddish mouths and teeth, due to irregular production of the heme pigment. Porphyria is hereditary, so there may have been concentrations of sufferers in certain areas throughout history. http://science.howstuffworks.com/science-vs-myth/strange-creatures/vampire5.htm

  • I'm actually changing my designation of the answer to this one because you provide some good background here. Is there any chance you can add to it with a few links to back it up or that would provide more detail?
    – Tango
    Mar 25 '14 at 3:54

From the Wikipedia article:

Vampires are mythological or folkloric beings who subsist by feeding on the life essence (generally in the form of blood) of living creatures, regardless of whether they are undead or a living person

They are drinking blood because they are stealing "life" from another creature. Since they are generally not considered alive themselves anymore.

Additionally from the same article:

However, it is Bram Stoker's 1897 novel Dracula that is remembered as the quintessential vampire novel and which provided the basis of modern vampire fiction.

Modern day vampires for the most part will loosely establish the pattern created by Bram Stoker. Some have expanded the mythology to say that vampires can survive on any blood, such as from other animals. Examples are Anne Rice in the Vampire Chronicles, the Blade movies, and Underworld. Others have made it so vampires lack certain traits (such as hemoglobin) which they can only acquire by consuming the blood of others (I, Vampire).

In short:

Vampires have to drink blood because that is the prevailing cultural association with vampires.

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    Indeed. And Terry Pratchett even makes it explicit: vampires drink blood out of habit/expectation, and they can give it up if they try. Jan 12 '12 at 19:48
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    @DanielRoseman I'm not addicted. It's just a crutch I've come to depend on to get me through day to day life. Jan 12 '12 at 20:31
  • Thank you for giving a good answer, instead of just saying it couldn't be done!
    – Tango
    Jan 13 '12 at 21:59

I'll take a stab at possible explanations, but my answer will necessarily be very incomplete as the universe if full of different kind of vampire canons.

  • Replenishment of blood as biological liquid (specifically, oxygen carrier); or alternately just for extra hemoglobin.

  • Blood as nutrient (more easily digestible, or the ONLY digestible by Vampire)

  • Evolutionary enhancement to assist in propagation of the species, since blood sucking enables infecting the victim with Vampire virus/genetic material/magic. Basically, the same reason humans have sex for recreation (assuming that 100% of the feeding doesn't result in Vampire conversion in a given canon in the first place).

  • Blood carries some sort of life force/bioenergy/chi/etc... that is what the real nutrient is. Blood is merely the vessel.

  • Blood is merely symbolic, and bioenergy/chi/emotions/etc... is what really is being consumed (IIRC, Force Vampires from SW canon fall under that).

  • Blood provide rejuvenation effects.

  • Sexual overtones. IIRC, in modern police psychiatry, any damage to the neck from bites is likely to be interpreted as such.

  • Good answer -- thanks. I picked the other, though, because he had some background to show where it came from -- but yours was a help. (I did upvote it, if that matters!)
    – Tango
    Jan 13 '12 at 21:59

As said in the Blade movies vampires can't produce sufficient amounts of hemoglobin so they have to feed on human blood.


In the The Vampire Chronicles, they do it because the life essence from the blood is the only way the spirit that animates them can replenish the energy it's using. However the ancient ones don't need it. It refreshes them and increases their physical and psychic strength, but they don't need it.

  • Can you list a specific book and page number? Maybe a quote?
    – miltonaut
    Dec 9 '16 at 6:13
  • Any book after The Vampire Lestat where the POV is one of the ancient ones.
    – Harlemme
    Dec 9 '16 at 20:27

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