This may have been mentioned already and I certainly don't know much about chemical Penis Enlargement at all but a quick research on Prostaglandin revealed the following possible adverse effects:
http://en.wikipedia.org/wiki/Prostaglandin_E1
Apnea
Flushing
bradycardia
hypotension
tachycardia
cardiac arrest
edema
CHF
hyperemia
second-degree heart block
shock
spasm of right ventricle infundibulum
supraventricular tachycardia
ventricular fibrillation
Fever
seizures
Cerebral bleeding
Diarrhea
Urethral pain
urethral burning
urethral bleeding/spotting
testicular pain ( Muse only)
Hematologic
DIC
bleeding
Cortical proliferation of long bones
sepsis
penile pain
prolonged erection
penile fibrosis
injection-site hematoma
penis disorder
injection-site ecchymosis ( Caverject only)
back pain
pain
pelvic pain
accidental injury ( Muse only)
Guys, be careful injecting things into your body. Not trying to be a downer or insinuate that anyone doesn't know what they're doing. Just saying, this scares the shit out of me.