From erowid, side effects of mushies:
side effects of 4-ACO-DMT:
NEGATIVE
intense feelings of fear
headache, usually as effects wear off, sometimes beginning the next day, lasting for up to 24 hours
nausea, gas, gastrointestinal discomfort, especially when mushrooms are eaten raw and/or dry
mild to severe anxiety
dizziness, confusion
lightheadedness or fainting (in cases of lowered blood pressure)
can precipitate or exacerbate latent or existing mental disorders
working memory disruption (reduced ability to do tasks requiring current remembering and attention)
side effects of 4-ACO-DMT:
NEGATIVE
(likelihood of negative side effects increases with higher doses)
anxiety / fear
difficulty speaking
motor impairment
stomach discomfort, nausea, vomiting, gas
intense or overwhelming visual disturbances
overwhelming thoughts and ideas
disturbing hallucinations/mental visions
paranoia / insecure feelings
sweating / chills / flushing
(severe) uncomfortable stimulation (mental and physical)
sleeplessness
(significantly) elevated heart rate
muscle fatigue/pain/aching
(severe) mental confusion
