The adverse effects of pethidine administration are primarily those of the opioids as a class: nausea, vomiting, sedation, dizziness, diaphoresis, urinary retention, and constipation.
Pethidine has serious interactions that can be dangerous with monoamine oxidase inhibitors (e.g., furazolidone, isocarboxazid, moclobemide, phenelzine, procarbazine, selegiline, tranylcypromine).