Why don't people who claim to be internally allergic to H2O molecules have an allergic reaction each time they swallow their saliva, which is almost entirely made up of H2O molecules?

[LarsKnowles]

I've seen several people going to the news claiming to have an internal allergy to water to the extent that drinking a sip of water causes a (potentially fatal) internal allergic reaction, such as anaphylactic shock or swelling of the throat. Why don't they have an allergic reaction whenever they swallow their saliva? Isn't it mostly water molecules? Saliva constantly coats the mouth and throat so why aren't their throats swollen shut constantly? Saliva is 99.5% water. It's even more pure than seawater.

Tessa Hansen Smith, an Instagram celebrity who goes under the Instagram handle of livingwaterless, is one of the latest claimants of internal water allergy. She claims she has an internal (mouth, throat, internal organs, veins/bloodstream) and external (skin) allergy to water molecules. She claims she has a very painful internal reaction to intravenous saline, explaining that this is because saline contains water molecules, and the immune cells in her blood are reacting to the presence of water molecules. 

Edited September 16, 2022 by LarsKnowles