I'm also guessing that it wasn't pure Ayahuasca brew (ie. Ayahuasca vine and Chacruna). How did they come to the conclusion that it was an allergic reaction?
Sounds more like a potential mix with what many in Peru refer to as Toe (pronounced Toe-A)
Basically the same thing as Jimson weed, trumpet flowers, brugsmania, Datura, etc.
I had a friend die after ingesting some Datura tea with several other people while camping. They found his body, fully clothed underwater, in a pond next to where they were camping. He probably walked into the water thinking he was walking on something other than water. One of the other guys wasn't found for 2 days, and was still totally delirious, seated in the middle of a bunch of thorny, pricker bushes.
Datura is used to extract "Scopolomine". Google "Scopolomine and Columbian criminals". Very powerful drug.
I would strongly advise anyone going for ceremony in S.A., to make sure that they only use Aya vine and Chacruna (Psychotria Viridas) in their brew. Don't be shy about asking what they use to make it. The last time I went to Peru, they said they also put a bit of "Sanango" bark in the brew. When initially asked, they said it was just a bark that helped in the cleansing. What the head of the retreat fessed up to after our first ceremony was that "Sanango" is Peruvian Iboga root (ie. Ibogaine like). I couldn't believe that he gave this brew to everyone without warning us that they had put Sanango in the Aya brew.
DATURA, TOE, BRUGSMANIA, TRUMPET FLOWERS, JIMSON WEED, DEVIL'S WEED, ETC. ARE EXTREMELY DANGEROUS AND POTENTIALLY FATAL. UNLESS YOU WANT TO TEMPT FATE, STICK TO A BETTER, LESS DANGEROUS COMPOUND!