In response to the question...
I noticed that this question has been up on the internet for a while but I had just found this and was just researching now.
And so first I would like to say that just about anything can give people allergic reactions.I'm honestly not exaggerating.So its not impossible for you to have them, it's just less likely.An allergy to ecstasy is somewhat rare but not to say it isn't possible.
Im reading the comments below and the word irritants is used and I think its appropriate for your situation.If it was really an allergic reaction you had to the pill and not just you bitting or you playing with your lips then I would just be a little careful taking them.It is kinda weird that
only your top lip got a reaction though.
A comment below says that an "allergy to MDMA probably isn't possible..." and I'm sure some people probably agree.
I on the other hand don't think so, I am on of those people that get reactions to
some ecstasy pills.
3 years ago I had tried ecstasy for the first time and frankly liked it.So I used it again and on the 3rd time I used ecstasy I had 2 Blue A's pills in which during the "roll" I had noticed my face and arms had gotten a little red.I thought it was normal, since ecstasy does get you up.Towards the end of my roll ,besides my redish tone

my friends had noticed that my whole face had swelled up significantly & later my whole body.My skin didn't feel as smooth as it normally would, it felt slightly rough.This had worried me a bit so I took a benadryl after, but that didn't help at all.

The next day I was still as fat as a sumo wrestler and even more so. On the 3rd day the swelling started to go down but I started to peel all over my body.My hands,feet and nose looked like they were covered in dryed up Elmer's glue.Since benadryl wasn't working for me I just let myself heal.I figured it was nothing that severe because after all these nasty side effects it had just caused me external effects.Other than that I felt normal.I didn't have any trouble breathing or anything like that.I was back to my usual self 2 weeks after.

The difference between these pills and the other ones that I had tried before were the white dots they had all around them.They were probably mixed with something else.
I was online looking for similar situations and came across this page.I really don't know why this happens to me but if someone has a clue please let me know.