I didn’t want to reblog the whole post this was from because I’ve posted my thoughts on the rest of it on a different thread, but I wanted to share @teacup-occamy‘s theory:
“I think Newt might have only been saying he would use the venom to remove bad memories because he was researching it as a way to counteract an obscurial. Seems the safest way would be to remove the bad memories so the child didn’t need to suppress their magic anymore and the obscurus could be removed or dealt with, etc, since it was a reaction to the child’s fear/anger/despair.”
This is brilliant. It totally makes sense. We know that Newt was able to separate the Obscurus from the Sudanese girl just before she died. Perhaps this was how.