Medical Question About Allergic Reaction

[lisab]

How come lips swell as part of an allergic reaction? What is in lips that makes them susceptible to reacting like that?

 

[Jack the Stri]

Allergies result from an excessive response to an allergen (no secrets there). Basically what happens is that histamines and other molecules are released (by mast cells and basophiles I believe, it's been a while) that cause a difference in permeability of the blood vessels. Pressure then causes proteins and whatnot to leak out of the vessels, increasing tissue osmotic pressure and thus causing swelling.

 

[lisab]

But why the lips? If the histamines are released into your general system, why isn't the reaction more universal?

This comes up because someone at my work had an allergic reaction over the weekend. He had not eaten anything for several hours beforehand, just all of a sudden his lips swelled. Sort of freaked him out - understandably so!

 

[Jack the Stri]

It's for the same reason asthma is localised to the airways and eczema is localised to the skin. I remember something about it being due to the responsive immune cells only being present in a certain tissue instead of going systemic, but I'm not sure.

 

[Proton Soup]

But why the lips? If the histamines are released into your general system, why isn't the reaction more universal?

This comes up because someone at my work had an allergic reaction over the weekend. He had not eaten anything for several hours beforehand, just all of a sudden his lips swelled. Sort of freaked him out - understandably so!

the only thing i can think of at the moment is that the skin is so thin on the lips, so it is more sensitive to allergens. you will see this some in contact dermatitis from say poison ivy (rhus dermatitis). thick skin on your palms may be unaffected, but thinner skin on your wrist is. the reaction can be a bit time-delayed, too.

the only other guess might be the abundance of nerve endings there? i really don't know with this.