Can you boil slowly to death without feeling it?

Just read this in a book, and my mind immediately went “Really?” So I came to the best source I know.

The book holds that if you’re in a tub, and the water temperature is gradually raised, you’ll boil to death without ever feeling it.

Now I understand that if the temperature is increased marginally and you are given time to adjust you probably won’t feel it for a while, but is there not some temp that your body screams, “OK, enough!”?


Flesh will scald long before the temperature gets anywhere near boiling. Scalded flesh is extremely painful. Believe me, the body will respond to pain sensations before the water hits 130 degrees.

Well, I can think of one way, but it’s not the way it was done in the book. If you lower the air pressure gradually, then the person in the tub will eventually pass out. And, if you then lower the air pressure enough (and raise the temperature enough), it will also boil.

I suspect that if you raise the temperature of the water high enough, the person in the water will also eventually pass out and eventually die, long before boiling point is reached.

Humans can survive amazingly high air temperatures , but only because the body has effective cooling methods that depend largely on evaporation. If the body is mostly submerged, then those cooling mechanisms won’t work and you’ll likely get fatally overheated even at relatively low temperatures.

As the water temperature is slowly rising you will probably pass out from hyperthermia, slump over into the water and drown. :smiley:

WAG Fill you hot tub with comfortably warm water and turn on the heaters! :wink:


Execution by boiling was actually used several times in England, starting in 1531; according to Charles Panati in his book Panati’s Extraordinary Endings of Practically Everything and Everybody he notes that the first time it was used was to execute a cook who had attempted to poison his employer and employer’s family. The condemned man was placed in a kettle of water which was then set over a fire and brought to a boil. Records indicate that it took him over two hours to die (“sweating and simmering to death” as Panati put it.)

I doubt that one wouldn’t feel being boiled however slowly the water is brought to temperature.

It’s a pretty common piece of trivia that’s told about cold-blooded animals (specifically frogs) but I’ve never heard it applied to warm-blooded animals, and I don’t believe it.

There’s a Darwin Award (possibly made up) re: couple that jiggers the thermo on the hot tub, drinks a couple of bottles of wine, end up dead–cooked–in the morning.

Couldn’t find it on the darwinawards site.

How much heat, for how long, does it take to kill someone? I know if you have a fever over 104 or so they (medical folks) worry. Is “boil to death” what we’re literally looking for here, or is any old death adequate to answer the OP?

Your body’s normal heat control mechanisms do not shut off just because the temperature is increased slowly. If the water temperature is warm enough to prevent normal heat dissipation from the body, you will become uncomfortably hot, sweat profusely, and eventually reach fluid exhaustion and hyperthermia just the same as if you were walking through the Sahara desert (but perhaps without a pressing need for sunglasses and lip balm). I don’t know about you, but after a few minutes in a 42 degree pool I am more than ready to get out.

It’s an urban legend even when said of frogs.

The sentence for money counterfeiters in France was often boiling. Don’t ask me why…

The sentence for money counterfeiters in France was often boiling. Don’t ask me why…


(“Expenses : For a pot bought in order to boil money counterfeiters in Montdidier : 100 shillings”)

It happens in Japan. People get drunk and then fall asleep in the ofuro (tub) but are not cooked. According to various sources (sorry, all in Japanese) the two main causes are heart attacks and drowning.


My uncle is reported to have once wanted to cook some crawdads (sic?) when he was young and instead of bringing the water to a boil then throwing the suckers in, he placed them in cold water and heated it up.
According to the accounts, when the water started getting hot, the crawdads began flailing and screaming* and took a horribly long period of time to die.

  • My brain might have made up the bit about screaming since I was told this.

I used to design torture equipment (er, I mean test equipment) for a neurobiologist who was studying pain. A lot of our tests involved heat and cold. I can tell you from experience that the human body does some weird things with respect to heat and cold. For instance, it has a hard time determining absolute temperature, but a much easier time determining relative temperature, so you can in fact make minor temperature changes slowly and people often won’t notice. You can take a temperature probe and put it on someone’s skin, and if you slowly raise the temperature, they’ll tell you that it is staying the same. Then you suddenly cool it down to its original temperature and they’ll tell you it dropped to being colder than what it started as.

In some respects this legend is based on some real effects that happen in the human body, but it only works so far. I found that if I slowly increased the temperature, my heat pain threshold went from about 44 to about 47 deg C, but now matter how slowly I increased the temperature, once it got about about 47, it f-ing hurt. The “ok enough” temperature varies a bit from person to person, but it’s usually somewhere between 42 and 46 deg C. If you play around with heat torture devices all day long you get a little immune to them, and researchers who work on this stuff usually have a pain tolerance closer to about 45 to 48 deg C.

There’s no way in heck you are going to get the temperature above 50 deg C without someone screaming in pain, no matter how slowly you raise the temperatuire. But as others have pointed out, you can die of overheating long before you literally get boiled to death.

Are you sure those temperatures are correct?

42oC is only a 5o above normal body temperature. Consider that the recommended bath water temperature for babies is ‘lukewarm’, which is near enough 37oC. You seem to be saying that some adults can’t tolerate water that is marginally above tepid, at about the temperature where we throw out coffee because it’s gone cold.

The ‘recommended’ household hot water temperature is 52oC. I just can’t see any adult would be screaming in pain with water temperature of 48oC much less 45oC. 45oC would be about the coldest I would ever willingly shower under.

I’ve lived and worked in air temperatures above 47oC. And that means that all metal surfaces in the shade were also above 47oC. Most parts of the tropics and subtropics experience a few days every year above 42oC. Nobody, even the most sensitive, ever express any concern from simply touching doorknobs or pens. You certainly wouldn’t say that you felt uncomfortable at those temps. The only time things become painfuly hot at those temperatures is if they’ve been lying in the sun.

I think you’ve got some error in your figures there. To me they seem to be out by at least 10oC. No way would anyone consider 47oC from water or metal touching the skin to be anything other than mildly warm. Certainly not painful.

Babie in Japan are bathed at slightly hotter temperatures than western babies, at about 40C which is hand hot.

Japanese baths for adults are usually in the 40C - 43C range. Hot spring and public baths often have thermometers over each bath, and you can certainly tell the difference between a 40C bath and a 42C one.

Our hot water is set at 44C during the winter, to allow for a bit of cooling as it comes through the pipes, and at 40C in the summer. If your water was set at 50C or above I have no doubt that you would be scalded.

My son got rather bad burns over his legs the first day we moved into our new house, and I had misset the water temperature to about 46C. He jumped into the bath without testing it first. I yanked him right out when he screamed, and ran cold water on his legs till they cooled. No blisters but they were stingy and red for a couple of days, and he couldn’t sleep that night.

Oh, and both my kids (and me!) have been burned by metal slides in summer Japanese sun - they were BLISTERING hot.

The air temperature at the time was probably in the 38C-40C range. Not so very hot.

There’s no doubt that metal lyinging direct sunlight can get very hot, a point I made above. That’s because it can absorb solar energy directly and get well above air temps. However contrast that with metal insode a house in 42oC temperatures. It’s by no means uncomfortable tootuch even for themost sensitive person depsite being at 42oC. Even at temperatures above 45oC it’s never unpoleasant or remotelypainful to handle objects at room temperature.

I also think your thermostat may be broken if your child suffered bad burns within seconds like that. Remember that “most people bathe in 43°C” ( tech_domestictemp.htm). And most children bathe at 41oC. ( From that same reference a child needs 10 seconds exposure at 60oC for very superficial burns of the type you describe to develop. Since your child was pulled out as soon as he screamed I’m assuming he was in for less than 2 seconds. It seems a safe bet the water was closer to 70oC than 46oC.

You are comparing a variety of different things of different sizes and rates of heat conduction. Air isn’t a very good heat conductor. You can easily stay in a sauna of close 90 degrees celsius and not feel painfully hot. Small objects at that temperature don’t hold enough heat to produce pain.

We’re talking about immersion in water, which can quickly conduct a lot of heat to the entire human body. 42 degrees won’t cause pain for a lot of people (it does for me). But if you stay in there a while, your body will get uncomfortably hot… not painfully, but a very palpable sensation of overheating that will force you to get out if you’re able. If you are forced to stay in, or have passed out from intoxication, you do run the risk of hyperthermia and eventually death.

Geez y’all. Hold down the Alt key and enter 0176 on your number pad to make a proper degree symbol (°)