Biting living people isn't easy and can be quite a pain for the one who bites. Human jaws are not made to bite stuff while it's still alive.

An easier way to infect other people and turn them into zombies would be projectile vomiting.

But I'm running into a problem, how many times would a zombie be able to use this method before it is forced to refill? Like how many times can it spit vomit before it has to fill its stomach again?

  • 3
    $\begingroup$ Sorry to everyone for putting strange fetishes, apocalypse clichés and vomit in the same question. $\endgroup$
    – user81643
    Commented Jan 8, 2021 at 23:08
  • 6
    $\begingroup$ Why bite, when you can lick? Have all the flavor of the skin and keep your teeth intact. In the manga "Ranger Doll", zombies do that instead of the crunchy, bloody bite ^^. It's still nasty, though. $\endgroup$ Commented Jan 8, 2021 at 23:27
  • $\begingroup$ i heard when our body die our stomach acid eat our body though. $\endgroup$
    – Li Jun
    Commented Jan 8, 2021 at 23:49
  • $\begingroup$ your skin is pretty good protection from infection, the point of a bite is to pierce skin. Also a human bite is still very powerful an human can easily bite the fingers off a hand or tear off a decent chunk of flesh, weaker than other animals is not the same as too weak to do significant damage. $\endgroup$
    – John
    Commented Jan 9, 2021 at 22:54
  • 1
    $\begingroup$ Not an answer so it goes as a comment: Spit instead of vomit. Have "bacteria" build up in the mouth and throat. Spit to blind victim. Victim flees, blinded and in pain. Z follows after. Z dips it fingers in its mouth and reaches and scratches at vitctim. The Z could vomit up some stomach fluid, like a cow when it rumnates, and then spit. I then rapidly continue thinking that the stomach would be highly poisonous and a Z cut in the stomach tract should be handled with care. Exposed to air or sun the poison would rapidly deteriorate so a Z must be both deheaded and degutted. FWIW $\endgroup$
    – LosManos
    Commented Jan 10, 2021 at 10:35

4 Answers 4


abestrange assumed 30 spits per day, I'll see what I can come up with.

Maximum liquid contents for human stomach: On average, the human stomach holds about 1 liter of fluid. However, the human stomach can stretch to hold about a gallon (slightly over, but not by much). So, it's safe to assume we have a gallon to work with.

As abestrange pointed out, zombies likely have an increased rate of Gastric Acid Regeneration (GAR). Also pointing in their favor is the fact that traditional "puker" or "spitter" zombies have distended stomachs, a clear indicator of increased stomach capacity.

Assuming two cup's worth of vomit for each attack, a gallon's worth gives us eight vomits or spits. This would be for a regular zombie that lacks an overgrown stomach, which I assume would hold a lot more fluid; let's say sixteen gallons. That's 128 spits.

If we go for a liter (4.25 cups per liter is a good estimate, it's really 4.22675, or rounded up, 4.23 cups) instead, that's 3 vomits for a regular zombie and 48 spits for a "bloated spitter."

On a final note, what's wrong with biting or scratching? Biting and scratching can do a surprising amount of damage (not speaking from experience here, but I have a pretty good idea of how damaging those are), and besides that, after your zombies run out of fluid, they're going to need another defense/attack/infection method. Not only would fangs and claws help a lot in making your zombies deadly, but any sane person can and should be freaked out when people are biting and scratching. It's just not natural.

  • $\begingroup$ Biting people is already dangerous for the living, one can crush bones with molars but can't pierce skin with incisors, at least not to the point of reaching muscle or veins or even fat. More force would either damage the front teeth or cramp maybe dislocate the mandible muscles, muscles which are small, really small. Zombies would hurt themselves even more. A person biting another person, is like pushing a metal knife onto another metal sheet... Both get damaged, but the knife breaks first. $\endgroup$
    – user81643
    Commented Jan 11, 2021 at 21:32
  • $\begingroup$ Suggestion: use either metric or imperial units (or both side by side), not alternating between them. $\endgroup$
    – KeizerHarm
    Commented Jan 11, 2021 at 22:13

Vomiting in non-undead humans is a reflex that's designed to empty the entire stomach. Basically, it happens when your body thinks you've eaten something that would be harmful to digest like poisonous berries. This means, that without "refills", your zombies could basically only projectile vomit once before they're limited to only hucking up dregs. They would need to eat/drink between attack vomits and the people who become zombified would need to have eaten recently to make sure they've got a full stomach.

It would be far more effective to have the zombies cough, sneeze, or simply exhale contagion if you want to give them a breath-attack. Airborne diseases are even more nasty than contact-transmission ones and having the zombies constantly exhaling zombie-disease would also add some potentially interesting worldbuilding:

  • Areas with high zombie populations become "death zones" because the disease in the air is replenished faster than it is dispersed
  • People need to make sure they don't camp downwind from large wandering hordes
  • Gas masks and air filters become just as critical to survival as food and water
  • 5
    $\begingroup$ I have to disagree with your vomit turns limitation. Sometimes I get sick and happen to vomit two to three times before drinking water or eating. Physiological changes to the undead body can even enhance vomiting capability (as pointed out by @abestrange). Their acid could be even stronger, capable of damaging the outer layers of skin thus opening the path for the zombie vector. $\endgroup$
    – Pedro
    Commented Jan 9, 2021 at 7:59
  • $\begingroup$ @Pedro human stomach acid is already some of the most acidic on the planet PH of 1.5, not matter what yo do human stomach acid is not eating through skin. also big difference between vomiting and projectile vomiting. $\endgroup$
    – John
    Commented Jan 9, 2021 at 23:02

The issues you're going to run into with trying to move to a projectile based infection vector is that your exposed target surface area is MUCH smaller. Almost anyone has a strong enough jaw to break skin almost anywhere on another human, even through most clothing.

Spitting at a target is going to require hitting their face, and a large number of commercially available products can stop whatever fluid you are spitting from being effective.

Furthermore, spitting range is only going to be a few feet at best. If your zombies have already closed that distance to their target, why have them stop, take aim, and spit when they could just continue running/ shambling and bite and scratch them?

Humans produce around 1.5 Liters of Gastric Acid daily though, your zombies could double that. Assume each spit is 100mL and you've got 30 spits per day.

Voiding the entire stomach in a single go would probably be wasteful and ineffective, but spitting a solid mouthful a time might be a good balance between volume, range, and accuracy.

  • $\begingroup$ I might just have really thick skin then $\endgroup$
    – user81643
    Commented Jan 8, 2021 at 23:16
  • $\begingroup$ Spitting acid/ venom at your enemies eyes is a great way to temporarily distract them though. The Spitting Cobras use that as a defense mechanism. Adding it to the arsenal wouldn't hurt, but wouldn't be as reliable as just plain ol' bitey-scratchy. $\endgroup$
    – abestrange
    Commented Jan 8, 2021 at 23:25
  • $\begingroup$ 30 spits per day is a lot of fluid. If you ran a human through a blender you only get about 42 liters of fluid. $\endgroup$
    – John
    Commented Jan 9, 2021 at 22:58
  • $\begingroup$ I also said only 100mL per spit, which is only about 3 oz at a time. You are much better to have multiple smaller "spits" than a single large one, especially since you need precision to hit vulnerable areas of your target. $\endgroup$
    – abestrange
    Commented Jan 11, 2021 at 18:37

Your zombies will vomit once or twice before needing to fill up again, and if there's a second time it won't go that far. You could make them intelligent enough to still use knives, sharp edges, etc instead, open wounds, then spread the virus through saliva. Maybe they bash their victims on debris and rocks till they get open wounds.

  • $\begingroup$ better question where are they getting the fluid to replace it, your body does not have all that much fluid in it. $\endgroup$
    – John
    Commented Jan 9, 2021 at 22:55
  • $\begingroup$ I assumed they'd still drink water and people, or it would be a one time thing. $\endgroup$
    – Tanya
    Commented Jan 11, 2021 at 12:13

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