Don't ask me where...but I have often heard that drowning in salt water is less painful than drowning in fresh water.

At first I thought this was true because the salt in seawater kills brain cells after it has entered the blood stream.

However, I recently learned that this is not true. Salt water has higher concentrations of dissolved substances than blood and body tissues, so it is unlikely to enter the circulation. This means water is more likely to move from the capillaries of the lung into the air spaces containing the salt water (due to osmosis).

In contrast fresh water is more likely to move into the capillaries from the air spaces of the lung because of the higher concentrations of dissolved substances in blood and body tissues.

The best explanation for this "phenomenon" would be that seas and oceans tend to be cooler than fresh water, so you are more likely to develop hypothermia. This will cause drowsiness and confusion with the result that the person may be less aware of the watery end awaiting them. This is where the myth about drowning in salt water being less painful than fresh water may come from - the drowning person is pleasantly numb to the experience.

As I have heard it told, the asphyxia that occurs with
drowning, causes a tremendous orgasm prior to death...
A little cookie for the road to your eternal reward,

Fresh or's all the same in the dark!

Osmosis is the movement of water through a semi-permeable membrane from a region of high concentration to low concentration (of water). Adding salt, sugar, whatever's in cytoplasm, etc. to the water lowers the concentration of water.1 External skin is keratinized - the cells have a large amount of keratin, a hard-wearing protein that resists water. This greatly reduces the rate which water can enter and leave the cells. Mucous membranes, such as those inside the nose and throat lack this keratinization, and can be damaged by water entering and leaving them.

A hypertonic fluid, for example distilled or fresh water, inside the nose will cause the cells to take in water, and possibly explode. A hypotonic fluid, like sea water, has a lower concentration of water than the nasal cells, and so will cause water to be drawn out, possibly killing them. Damage to the cells of the mucous membranes is what hurts. Try opening your eyes (which are also mucous membranes) under water in the sea, and in a river, lake or swimming pool. In either fresh or salt water, your eyes will hurt, due to damage by osmosis. Drowning in fresh and salt water would probably hurt just as bad, but to drown in a fluid with a massively different concentration of water, such as the super-saturated saltwater of the dead sea would probably hurt a lot more.

An isotonic fluid, such as nasal spray or sterile saline attempts to have the same concentration of water as the cytoplasm of the cells inside the body, so no water moves either way. These substances can come into contact with mucous membranes, such as the eyes and nose without damaging them, and thus can be used to convey drugs (nasal sprays), or wash the membranes (eye washes) without hurting. Isotonic drinks will (in theory) rehydrate the body if it is dehydrated, without depleting essential salts.

1 - This is not looking at things the conventional way round - osmosis is usually considered in terms of the concentration of solute in water. Thinking of the concentration of water in solute, however, makes things simpler when considering a range of substances dissolved in the water at once.

Without actually dying, I recently acquired some more data on this question, and have come to my own conclusion.

On the fresh water side of things, I've many times had this experience, as I'd guess you have. You're in the shower, you bend down to pick up the soap or wash between your toes, and the water streams down from your chin into your inverted nose. Not a good feeling, the minor sting that it provides. Most of us aren't doctors, but we've probably heard that there aren't many places in the body where the blood comes closer to the outside world, and we see that illustrated so close to home, many a morning while the coffee is brewing in the kitchen.

I had the opportunity to compare this with salt water the other day when I was at the Tri-Counties Blood Bank for my monthly platelet donation. When I first started donating platelets, they used small, portable Haemonetics machines, except for one big Kobe monster that looked like it belonged in the control room of a power plant. The smaller machines are less efficient than the Kobe, and usually the donation process takes longer on one of them, while ending up with less usable platelets and plasma. Eventually, I asked what the criteria were for putting a donor on one kind or the other, and was told that the staff had to learn about each individual, and whether their veins could stand up to the higher pressure that the Kobe used to return the mixture of plasma, red cells, saline solution, and anticoagulant to the donor's circulatory system. They told me of the rare occasions when the vein couldn't handle it; the word blowout was used. I think I probably heard more of a horror story than they intended. After about ten donations, they put me on the Kobe one day, but then I was back on the Haemonetics after that. Though there was no problem, I guess I didn't measure up.

I was quite happy with that situation, but the staff didn't like the smaller machines, and they were being incrementally replaced with new, incredibly smart units from Baxter. Arriving for my recent appointment, I found that the TCBB is now a Baxter-only shop, as far as platelet donation goes.

So I was hooked up, and the first drawing cycle commenced. My whole blood was diverted out through the needle, around and around the transparent spiral plastic tubing, and into the heart of the machine which, after having its way with it, dripped the plasma component into one bag, the platelets in another, and was ready for the first return phase. For some reason, there were three technicians huddled around the status display, including John, the most senior. As the direction of the flow in the tubing reversed, they asked me "Does that hurt?". I was, and I assume they were, thinking along the lines of excessive pressure. I said no, and they seemed suprised at that, as though whatever they were reading made them think that it should be. "Are you sure?". "Yes". A few more seconds, and then "Oh — that hurts. Ow!" They jumped into action, stopping the process, and told me that what I was feeling was saline solution being pumped into my muscle and other tissues, rather than into the vein. Despite the blood having been drawn quite without incident, they were concerned that the needle was badly placed.

I assented to an attempt to use my left arm instead and they brought out the special machine they use on the rare occasions when they need to continue a donation in the middle using a new needle. The tube was hermetically sealed, the needle removed and a new one emplaced, shortly to be jabbed into another vein, this time by a different nurse. The return process was resumed, and within seconds I felt the same pain as before. They stopped the return, and said I was done for the day.

I asked them why it hurt so much. I had always thought of saline solution as being essentially neutral in the body. I don't remember their explanation, but I was amused that even while I was talking with them, I was remembering this node on E2.

Let me tell you, it burns! I was amazed at how much it hurt. The other writeups here attempt learned speculation based on osmosis and intracellular pressures and whatnot. I'll leave them to it. But I've tried both, and if it ever comes to drowning, give me the fresh water!

People who die by drowning as a general rule don't die because their lungs fill with water. Actually, very little water, either salt or fresh, enters the lungs before death. Instead, drowning victims usually experience laryngospasm, the body's defense against water entering the lungs.

Laryngospasm is when a person's vocal cords spasm and close off their larynx or windpipe, blocking the flow of air or, in this case, water. It doesn't matter whether the water is fresh or salty; the crucial point is, when liquid of any sort enters the larynx the body reflexively closes it off.

Any water found in a drowning victim's lungs generally seeps in after death, when all the muscles in the body relax. Therefore, the osmolarity of the liquid should not make a difference in the amount of pain experienced while dying.

I would tend to consider it an urban legend that it is less painful to drown in salt water, since anyone who could speak as an authority on the subject would have to have been drowned in first one and then the other liquid.

The experience related by C-Dawg is called infiltration. It happens when an IV catheter slips out of the vein and the IV solution flows into the surrounding tissue instead. The pain is caused not by the salinity of the solution but by the increased pressure being locally experienced in the tissue. Our bodies are not simply bags of fluid, but an array of small, individual, mostly inelastic compartments, which generally stay at a fixed pressure. A sudden increase in pressure will always cause pain.

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