Naloxone, if given in single large-dose bolus, may precipitate opioid withdrawal in opioid-dependent patients causing patient distress and life threatening complications: seizures, non-cardiogenic pulmonary edema, and cardiovascular collapse.
Nice summary from emDocs (FOAMed):
How to dose naloxone?
Start naloxone with small doses, i.e. 0.04 mg, and not the standard dose of 0.4 mg IV/IM.
Naloxone can be lifesaving. However, given the high prevalence of opioid addiction and the rare but potentially dangerous complication of precipitated opioid withdrawal, the use of initial small escalating doses of naloxone can avoid the development of precipitated opioid withdrawal. An appropriate strategy is to start with 0.04 mg and titrate up every 2-3 minutes as needed for ventilation to 0.5 mg, 2 mg, 5 mg, up to a maximum of 10-15 mg.