[SkepticalDebunker (OP)]

Tessa Hansen Smith (LivingWaterLess) claims she's internally allergic to water when it touches her throat, her internal organs, and her bloodstream. She has an internal allergic reaction to intravenous saline, she explained it's because her bloodstream immune cells are reacting to the presence of water molecules. She says nurses have accused her of making it up. She says the only reason she can drink milk is because the fats in the milk surround the water molecules so they cannot be detected by her immune system. Is there any way for the immune system to detect or recognize water molecules?

[Kryptid]

Water allergies don't exist. She's either allergic to something in the water or having some kind of reaction that isn't allergies. The immune cells are already floating in a solution that is almost entirely water (blood plasma). If they aren't reacting to that, then they aren't going to react to water from an outside source either. Milk is mostly water as well: the water molecules in water greatly outnumber the fat molecules, so her conjecture isn't tenable.

[SkepticalDebunker (OP)]

Water allergies don't exist. She's either allergic to something in the water or having some kind of reaction that isn't allergies. The immune cells are already floating in a solution that is almost entirely water (blood plasma). If they aren't reacting to that, then they aren't going to react to water from an outside source either. Milk is mostly water as well: the water molecules in water greatly outnumber the fat molecules, so her conjecture isn't tenable.

I'm assuming aquagenic urticaria (which Tessa says she was diagnosed with) is a bit like electromagnetic hypersensitivity syndrome - where the physical reactions are caused by a mental illness?  (Tessa also claims she has ADHD, PTSD, and Hypothyroidism, among various other things.)

[evan_au]

Rabies was previously known as "hydrophobia" - they want to drink, but the victims gag and can't swallow.
They can't even swallow saliva, which leads to foaming around the mouth.

But if she was exposed to rabies virus, she would be dead (or, much less likely), recovered.
https://en.wikipedia.org/wiki/Rabies

[paul cotter]

Allergy to water ( or oxygen ) would be totally incompatible with life. I reckon she doesn't like washing herself!

[alancalverd]

The immune system is exquisitely sensitive to water and ceases to function in its absence.

[Deecart]

The immune system is exquisitely sensitive to water and ceases to function in its absence.

You can also say more clearly that the molecules involved in the immune system dont work when they are not surrounded by water molecules.
Not sure if this will help to answer the question : Can immune system react to water molecules ?

Here we are not talking of "absence of water" but of "presence", so the question remain open (in some logical way).

[alancalverd]

Yes, the immune system reacts to the presence of water by working properly.

[Deecart]

Yes, the immune system reacts to the presence of water by working properly.

This do no answer the question :
Why cant immune system react to water ?

First : What is the immune system ?
We dont care.
Here we are only talking of some small portion of the immune system, the immunoglobulin.
These molecules are generic peptids having at some position of their structure some variable structure having the ability to recognize some other particular molecules.
Can they recognize water molecules ?
No.
Because first the water molecules is what permit the immunoglobuline to have some neutral inactivity.
The neutral state is : A immunoglobuline with some water around : Waiting to be activated.
With no water, nothing will happen.

Then, to "activate" the immunoglobulin you need to have some "antigen", some bigger molecule as water.
Some protein or some polysacharide per example.

Water is too smal to induce any "activation" and is part of the neutral waiting state of the immunoglobulin.
Thats all.

[SkepticalDebunker (OP)]

Yes, the immune system reacts to the presence of water by working properly.

This do no answer the question :
Why cant immune system react to water ?

First : What is the immune system ?
We dont care.
Here we are only talking of some small portion of the immune system, the immunoglobulin.
These molecules are generic peptids having at some position of their structure some variable structure having the ability to recognize some other particular molecules.
Can they recognize water molecules ?
No.
Because first the water molecules is what permit the immunoglobuline to have some neutral inactivity.
The neutral state is : A immunoglobuline with some water around : Waiting to be activated.
With no water, nothing will happen.

Then, to "activate" the immunoglobulin you need to have some "antigen", some bigger molecule as water.
Some protein or some polysacharide per example.

Water is too smal to induce any "activation" and is part of the neutral waiting state of the immunoglobulin.
Thats all.

That seems plausible but every year or so, I come across a news article of a person diagnosed with 'Aquagenic Urticaria' - also known as an allergy to water. In half of the cases I read about, the insides are affected.

[Deecart]

Aquagenic urticaria is not an allergic immune response.

Aquagenic urticaria, also known as water urticaria and aquagenous urticaria, is an extremely rare form of physical urticaria. It is sometimes described as an allergy, although it is not a histamine releasing allergic reaction like other forms of urticaria; it is more a hypersensitivity to the ions found in non-distilled water. In affected persons, water on the skin causes hives to appear within 15 minutes and last for up to two hours.

https://en.wikipedia.org/wiki/Aquagenic_urticaria?oldid=271608552