Cotton Fever
Cotton fever is a self-limited febrile syndrome occurring in people who inject drugs, characterized by acute onset of fever, rigors, myalgias, and leukocytosis within minutes to hours after injection, typically resolving within 12-24 hours without specific treatment.
Clinical Presentation
Cotton fever presents with a distinctive constellation of symptoms that injection drug users often recognize themselves 1, 2, 3:
- Acute fever developing within minutes to hours after drug injection 2, 3
- Rigors and chills 3
- Myalgias (muscle aches) 3
- Nausea and vomiting 3
- Leukocytosis (elevated white blood cell count) 2, 3
- Self-limited course, typically resolving within 12-24 hours 2
Etiology and Pathophysiology
The syndrome is associated with filtering drug solutions through cotton balls or filters 1, 3:
- Enterobacter agglomerans (now reclassified as Pantoea agglomerans) has been identified as the likely causative organism, as cotton and cotton plants are heavily colonized with this bacteria 4
- Blood cultures have isolated E. agglomerans from patients with cotton fever, with the same organism subsequently found in the cotton filters they used 4
- Related Enterobacter species (E. asburiae) have also been implicated 5
- The practice of "cotton shooting"—injecting residual drugs extracted from previously used cotton filters—significantly increases risk 5
Epidemiology and Risk Factors
Cotton fever is remarkably common among people who inject drugs 1:
- Over 50% of people who regularly inject opioids report experiencing cotton fever 1
- Risk factors include:
Diagnostic Considerations
While cotton fever is often benign, serious infections must be excluded 2, 4:
- Blood cultures should be performed in all cases, as bacteremia with Enterobacter species can occur and may lead to endocarditis 4, 5
- Serious illnesses like pneumonia and infectious endocarditis must always be considered in febrile injection drug users 2
- Emergency physicians can diagnose trivial illness (including cotton fever) with 93% specificity in febrile adult drug users 2
- Trivial illness accounts for 16-26% of fevers in this population 2
Management Approach
The primary management is supportive care with careful observation 2, 4:
- Obtain blood cultures before initiating treatment 4
- Consider empiric antibiotic therapy given the association with Enterobacter bacteremia and potential for endocarditis 4, 5
- Short-term observation units may be appropriate alternatives to hospital admission for patients with presumptive cotton fever diagnosis 2
- Monitor for resolution of symptoms within 12-24 hours 2
- If symptoms persist beyond the expected timeframe, pursue alternative diagnoses aggressively 2
Prevention Strategies
Harm reduction counseling should emphasize specific practices to reduce cotton fever risk 6, 7, 1:
- Use a new filter ("cotton") with each drug preparation—never reuse or share filters 6, 7
- Prefer membrane filters over cotton balls, as membrane filters are associated with lower cotton fever rates 1
- Use sterile water (boiled) or clean fresh tap water to prepare drugs 6
- Use a new or disinfected container ("cooker") for each preparation 6, 7
- Never engage in "cotton shooting" (extracting and injecting residual drugs from used filters) 5
Common Pitfalls
- Don't assume all fever in injection drug users is cotton fever—serious infections like endocarditis must be excluded with blood cultures and appropriate workup 4, 5
- Don't dismiss the patient's self-diagnosis entirely—injection drug users often recognize cotton fever from experience, but this should prompt appropriate evaluation rather than reassurance alone 3
- Don't discharge without blood cultures—even "benign" cotton fever can be associated with bacteremia requiring antibiotic therapy 4, 5