As I mentioned back in my post about allergies (and how they can apply to fiction), there are several types of allergies. Let's focus on what life's like for someone with contact allergies or contact dermatitis.
Reactions can range from itchiness or rashes to skin blistering and peeling off. Not everyone will have all types, but once you have one allergy, you're likely to have or develop more.
Someone's sensitivity to an allergen will also vary, though it'll probably get worse with repeated exposure, depending on if it's more of an allergy (antihistamine reaction) or an intolerance (body can't process it). Intolerances tend to get worse if you don't let yourself heal in-between exposures, but you can expose yourself, heal up, and expose yourself again—the reaction probably won't be any worse. Allergies, on the other hand, tend to get worse with repeated exposure.
So, what does all this mean on a practical level, either for worrying about friends' allergies or for creating a character with an allergy?
Since I have pretty much every type of skin reaction you can think of, I'll be using myself as a case study to demonstrate three types of reactions and what I have to do about it. (Short version: I read pretty much every label, and I usually end up regretting it when I don't.)
Trigger: most cleaning agents, including antibacterial handsoap. (Non-antibacterial handsoap can bother me, too, but not as much.)
Reaction: My skin gets thin to the point of touching stuff hurts. By the time it reaches the "painful to the touch" stage, it's also red and blotchy.
Degree of sensitivity: Medium
antibacterial soap: >1x every other day = too much; other soap: >1x in an hour or three = too much.
How this affects life: Obviously, I have to wash my hands. So I buy mild, non-antibacterial soap, and I wear vinyl gloves when cleaning or when performing messy cooking tasks. I also frequently treat my hands with oil (I like argan) or lotion (Desert Essence organics).
Trigger: tea tree oil. (My mother is castor oil.)
Reaction: skin blisters and peels off
Degree of sensitivity: Medium-high
If I touch even a small amount, I must immediately wash it off.
How this affects life: If something has "natural" on the label, I read it carefully. Chances are, it'll have tea tree oil. (I also watch for castor oil in the soaps I buy, so I don't hurt my mother.)
Trigger: berries (strawberries or raspberries) and some flowers
Reaction: rash (and with strawberries, trouble breathing)—if the soap uses natural ingredients
Degree of sensitivity: High
Can't touch most of them, and some I react to smelling.
How this affects life: I have to check the soaps at friends' houses before I do something that'll need me to wash my hands. I also have to be careful about the scents in my own soaps, lotions, body wax, etc. (I'll generally go for "fragrance free" or a scent like tea or cinnamon.)
So there you go—three examples of how a skin reaction can affect your everyday life.
I'm thinking next week, I might talk about allergies in regards toothpaste and tea. Anyone want to hazard a guess as to what can often be in both? I've mentioned the allergy before.
Do you know anyone who seems to read all soap labels before touching them? Can you think of a character you've read or written with a skin allergy? Do you think it's something you might like to play with?