As well as its needed effects, opium may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking opium, check with your doctor immediately:

Incidence not known
Difficulty having a bowel movement (stool) hives or welts nausea vomiting
If any of the following symptoms of overdose occur while taking opium, get emergency help immediately:

Symptoms of overdose
Anxiety
blurred vision blue lips and fingernails chest pain or discomfort chills cold sweats coma confusion constricted, pinpoint, or small pupils (black part of eye) cool, clammy skin coughing that sometimes produces a pink frothy sputum depression difficult, fast, or noisy breathing, sometimes with wheezing difficult or troubled breathing difficulty sleeping disorientation dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly drowsiness to profound coma fast heartbeat hallucination headache increased hunger increased sweating irregular, fast or slow, or shallow breathing lethargy lightheadedness mood or other mental changes nervousness nightmares no blood pressure or pulse no muscle tone or movement not breathing pale or blue lips, fingernails, or skin seizures shakiness shortness of breath slow or irregular heartbeat slurred speech stopping of heart swelling in legs and ankles unconsciousness unusual tiredness or weakness
Some opium side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Incidence not known
Itching skin redness of skin skin rash
It is possible that some side effects of opium may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice
Insomnia
Many report that the worst part of the psychological aspect of opium or opiate withdrawal is that they are unable to sleep often for days at a time and that this can be what takes the longest to get back into a somewhat normal schedule.

Intense Craving
People suffering from an addiction to opium or opiates are completely overcome with their obsession to use again and again. They say that they would do absolutely anything to use the drug again even when that means lying, stealing or worse because the desire to use again is so intense. Criminal activity has skyrocketed and more people are either ending up in jail or drug treatment due to drug addiction.