I grew up having terrible allergies, and fewer alternatives to deal with them than there are now.
I was accused of being fussy, a drama queen, rebellious, obstinate, and a bad child for refusing to eat foods I knew would make me seriously ill. I will hasten to add it was not my family who would do this, but children are frequently at the mercy of adults outside the family (school, camp, whatever).
When my skin was covered in rashes strangers would not tell me that would happen if I would just take regular baths, implying I was dirty.
Being refused entry to public pools due to a rash was always fun, too.
When I couldn’t breathe properly in gym class I was accused of being lazy and having a bad attitude. My coughing, wheezing, and staggering around due to lack of sufficient air was attributed to me acting out, not, in fact, what was really wrong - untreated asthma. I was made to feel so bad about being a lazy, nonathletic piece of crap by gym teachers that I was ashamed and never told my parents about these episodes - if I had, my asthma might have been caught much, much earlier in life.
When I went to camp one year I wasn’t allowed to take my allergy medicine regularly - the camp nurse said I “looked too healthy” to need them, even though it had been explained I needed to take them to prevent problems. When I started having a bad reaction I asked for them and was told asking for drugs was bad. When my eyes swelled shut someone finally called the nurse, who then freaked out and called my parents, breathlessly explaining I was to be taken to the hospital. Mom’s reaction? “Obviously you didn’t give her her medication. Why not? If you had, this wouldn’t be happening. Given her 50 mg of Benadryl right now.” Camp nurse refused, because, of course, mom wasn’t a doctor and couldn’t “prescribe” medicine. Camp got cut short for me that year, and I went to a different (and much more accommodating one) the following year.
Long term, the biggest impact has been on my social life. So much social life revolves around food, and there are so many common foods I can’t safely eat. I have often discovered that I have been systematically excluded from events because people fear inviting me - either fearing I’ll have a bad reaction, or they can’t accommodate my needs, or that it would somehow be less rude to simply not invite me at all rather than invite me and simply ignore that I pass over some or all of the food being served.