creation date: 2026-03-02 15:55
tags: Pathologies
Opioid Use Disorder
Background
Definitions
Opioids, indicated for pain relief, have effects for analgesic, CNS depression, and potentially euphoria. Opioid use disorder (OUD) is a substance use disorder involving misuse of prescribed opioid medications, use of diverted opioids, or use of illicitly obtained opioids (eg. heroin and fentanyl).
A number of slang terms describe opioid use:
- Intranasal: “snorting” or “sniffing”
- Intravenous: “shooting up” or “mainlining”
- Subcutaneous: “skin popping”
- Intramuscular: “muscling”
Opioid Types
Prescribed opioids
Opioids are prescribed for pain relief but may be misused or used by a person who the medication was not originally prescribed for. Types include:
- Opiates: compounds that occur naturally in the opium poppy (eg. morphine, codeine)
- Synthetic opioids: oxycodone and hydrocodone (semi-synthetic); fentanyl, tramadol, methadone (synthetic)
Nonprescription opioids
- Heroin: derivative of morphine; commonly administered via injection
- Opium: extracted from opium poppy containing morphine and codeine; commonly administered by smoking
- Endorphin: endogenous opioids
Clinical Presentation
Signs & Symptoms
Presentation may vary and can range from acutely intoxicated, in opioid withdrawal, or with no acute effects.
Acute intoxication
- Slurred speech
- Sedated (“nodding”)
- Pinpoint pupils (miosis)
- Fresh injection sites if administered via injection
Note that a patient with tolerance may show no acute effects.
Withdrawal
- Cravings for opioid
- Dysphoria and restlessness
- Rhinorrhea and lacrimation
- Myalgias and arthralgias
- Nausea, vomiting, abdominal cramps, diarrhea
Systemic syndromes
- Opioid-induced bowel syndrome - reduced GI motility causing:
- Constipation
- Bloating
- Early satiety
- Pain
- Opioid-induced hyperalgesia
- Liver fibrosis
- Leukoencephalopathy (rare)
- Opioid amnestic syndrome (rare)
Impaired social functioning
In patients with OUD, social functioning is likely impaired and extent is associated with severity and duration of the disorder.
- Mild: jobs and relationship may be maintained but interviewing may reveal problems
- Severe: impoverished, engaged in illegal behaviour; obtaining/using may becoming the organizing feature in their lives
History & Physical Exam
Screening
Screening should be done if there is evidence for risk of opioid misuse (eg. poor functional response to long-term opioid therapy, hep C/HIV infection).
Tools for screening include the clinician administered Rapid Opioid Dependence Screen (RODS) or the self-administered OWLS.
History
A detailed history of substance use should be obtained including:
- What substances
- Frequency of consumption
- Amount consumed
- Consequences of use
- Route of administration
Physical
Common complications of opioid use may be found. Assessment of routes of administration (nasal cavity, along subcutaneous veins) should be performed.
If acute intoxication is suspected, pupils and cognition can be assessed.
Risk Factors
Risk factors for opioid use disorder include:
- History of SUD
- Younger age (<40)
- Male sex
- More severe pain
- Co-occurring mental disorders
- Childhood trauma
- Family history of addiction and mental health problems
Diagnosis
Criteria
Diagnosis of OUD is made using the DSM-5 criteria.
The diagnosis requires at least 2 of the following 11 criteria (categorized by impaired control, social impairment, risky use, physical dependence) within a 12 month period:
- Opioid use in larger amounts or over longer period of time than intended
- Unable to cut down or control opioid use
- Great deal of time is spent to obtain, use and recover from opioid use
- Cravings
- Recurrent opioid use resulting in failure to fulfill major role obligations at work, school or home
- Continued use despite social or interpersonal problems
- Important occupational, social or recreational activities are given up
- Recurrent opioid use in physically hazardous situations
- Continued use despite physical or psychological problems caused by opioid use
- Presence of tolerance
- Presence of withdrawal
Work-up
Urine drug test
A urine drug screen can detect metabolites of morphine and heroins for 1-3 days after last use and occasionally longer for chronic users.
Note that fentanyl, methadone, and buprenorphine are not detected in routine detection urine test but specific tests are available.
Additionally, false positives may occur with rifampin, quinolones, and poppy seed ingestion.
Laboratory studies
To detect complications, the following should be ordered:
- Complete blood count
- Liver function tests
For patients who administer IV, recommend:
- HIV testing
- Hep A, B, C testing
- Syphilis serology
- Tuberculosis testing
Differential
Red Flags / Complications
Use of contaminated drugs and inadequate sterile techniques leads to infections:
- Cellulitis and localizied abscess
- Osteomyelitis
- Endocarditis
Needle sharing is also associated with an increased risk of bloodborne pathogen such as HIV, hep B, and hep C.
Other complications include:
- Overdose
- Motor vehicle accidents
- Increased risk of fracture
Management
Initial Treatment
Mild Disorder
Treatment of patients without physical dependence consist of pharmacotherapy and psychosocial treatment.
Naltrexone is the preferred choice as it completely blocks mu-opioid receptor, does not cause physiologic dependence or withdrawal, and can be changed to methadone or buprenorphine if needed. Options are:
- Long-acting injectable (LAI) naltrexone q monthly
- Naltrexone PO daily - only if highly motivated and refuse injections
Adjunctive psychosocial intervention include CBT, motivational interviewing, contingency management, family therapy, substance use disorder counselling.
While not recommended, psychosocial treatment alone may be an option if the patient has a history of prior sustained response, is highly motivated for treatment, and have strong supports.
Moderate to Severe Disorder
Treatment of most patients involve pharmacotherapy with adjunctive psychosocial treatment.
Initial pharmacotherapy include opioid agonists:
- Buprenorphine
- Methadone
The opioid antagonist naltrexone can also be used but is not preferred due to risk of medically-induced withdrawal. Supervised withdrawal is necessary before initiating it.
Adjunctive psychosocial intervention include CBT, motivational interviewing, contingency management, family therapy, substance use disorder counselling.
Assessment of Response
Assessment is typically made weekly for dose adjustments (buprenorphine) or even as frequently as daily (methadone, as part of treatment program).
An effective response is defined as sustained abstinence (≥6 months) from illicit drug use and no heavy alcohol use, as confirmed by urine testing.
Poor response after 6-12 months of treatment typically suggests re-examination of the approach is necessary. Modifications may include:
- Optimizing medication doses
- Increasing the frequency of psychosocial intervention
- Adding another modality of psychosocial intervention