Symptoms of Opioid Withdrawal
Opioid withdrawal manifests as a constellation of behavioral and physiologic symptoms that include anxiety, agitation, insomnia, tremors, increased muscle tone, nausea, vomiting, diarrhea, decreased appetite, tachypnea, tachycardia, fever, sweating, and hypertension 1.
Behavioral Symptoms
Behavioral changes are often the primary manifestation of opioid withdrawal and include:
- Anxiety and agitation - frequently the earliest signs
- Insomnia - disrupted sleep patterns
- Restlessness - inability to remain still
- Tremors - involuntary shaking
These behavioral symptoms reflect the neurobiological adaptations in the locus ceruleus and mesolimbic systems that occur with chronic opioid exposure 2.
Physiologic Symptoms
The autonomic and somatic manifestations include:
- Increased muscle tone - muscle cramps and bone aches
- Gastrointestinal symptoms - nausea, vomiting, diarrhea, decreased appetite
- Cardiovascular changes - tachycardia and hypertension
- Respiratory changes - tachypnea
- Temperature dysregulation - fever and sweating 1
Clinical Context and Severity
Opioid withdrawal is appropriately described as subjectively severe but objectively mild 3. Patients commonly describe withdrawal as akin to a moderate to severe flu-like illness. The pain associated with withdrawal is often described as incapacitating and can interfere with employment and housing stability 4.
Important Clinical Considerations
Timing and Risk Factors
Withdrawal symptoms can occur when:
- Opioids are abruptly discontinued or rapidly reduced
- Gastrointestinal absorption decreases (reducing oral opioid blood levels)
- Transitioning from intravenous to oral administration results in lower blood concentrations 1
Fentanyl-Specific Considerations
Patients who have transitioned from heroin to fentanyl use experience more frequent, more painful, and faster onset of withdrawal symptoms 4. This is a critical consideration in the current opioid crisis.
Rare Complications
While uncommon, delirium can occur during opioid withdrawal, though this is far less frequent than with alcohol withdrawal 5. Rule out other causes such as infection and sepsis when evaluating withdrawal symptoms 1.
Assessment Tools
For pediatric populations, validated scales include the Sophia Observation Withdrawal Symptoms Scale. For adults, the Clinical Opiate Withdrawal Scale (COWS) is an 11-item clinician-administered validated tool 1, 6.
Clinical Impact
Withdrawal symptoms are a key driver behind continued opioid use and represent a major barrier to opioid discontinuation 2. Among people who inject drugs, withdrawal symptoms are independently associated with increased health risks including receptive syringe sharing and non-fatal overdose 7. Fear of precipitated withdrawal from buprenorphine also serves as a significant barrier to treatment initiation 4.
The CDC guideline emphasizes that clinicians should advise patients about common effects of opioids including physical dependence and withdrawal symptoms when stopping opioids as part of informed consent discussions 8.