In "Exile" by Alejandra Pizarnik, the delirium she faces comes from the contradictory element of using drugs. The high that one gets from a drug is compared to the hell that follows. Comparing drugs to angels is fitting in that angels can be fascinating and beautiful but also horrifying in that they often can accompany images of death.
And who is not joyful while among poppies?
And who does not have a fire, a death,
a fear, something horrible,
even if it might come with feathers,
even if it might come smiling?
This implies that angels appear while in the intoxication of poppies. And clearly, many other negative factors are associated with the use of this drug that comes from poppy seeds.
To be under the influence of drugs is to be exiled from reality and with it comes the fear and death associated with angels.