Morphine has many side effects including the most dangerous which is respiratory depression. Common Morphine side effects are nausea and vomiting due to the action of morphine stimulating centers in the brain concerned with vomiting called the chemotactic trigger zone. Other central nervous system side effects of morphine are cough suppression, sedation, and dependence leading to addiction. Morphine can also cause histamine release, which causes itching of the skin and nose as well as a mild flushing of the skin.

Morphine side effects include but are not limited to:

• anxiety
  
• involuntary movement of the eyeball
  
• blurred vision / double vision
  
• constipation
• "pinpoint" pupils
  
• chills
  
• depressed or irritable mood
  
• itching
  
• cramps
  
• dizziness
  
• rash
  
• diarrhea
  
• drowsiness
  
• rigid muscles
  
• inability to urinate
  
• exaggerated sense of well-being
  
• seizure
  
• dreams
  
• light - headedness
  
• swelling due to fluid retention
  
• dry mouth
  
• nausea
  
• tingling or pins and needles
  
• facial flushing
  
• sedation
  
• tremor
  
• fainting / faintness
  
• sweating
  
• uncoordinated muscle movements
  
• floating feeling
  
• vomiting
  
• weakness
  
• hallucinations
  
• agitation
  
• abdominal pain
  
• headache
  
• allergic reaction
  
• abnormal thinking
  
• high/low blood pressure
  
• appetite loss
  
• accidental injury
  
• hives
  
• apprehension
  
• memory loss
• insomnia