Can Neozep or Bioflu Cause Erythema Multiforme?
Critical Clarification Required
The medications you're asking about—Neozep and Bioflu—are NOT bromazepam or fluoxetine. These are brand names for over-the-counter cold/flu combination products commonly available in the Philippines and other Asian markets, typically containing paracetamol (acetaminophen), phenylephrine, chlorpheniramine, and sometimes other ingredients like caffeine or dextromethorphan 1, 2.
Direct Answer Based on Individual Components
Yes, both Neozep and Bioflu can potentially cause erythema multiforme, though the risk is relatively low, primarily through their shared ingredient paracetamol (acetaminophen) and potentially through chlorpheniramine. 2
Component-Specific Risk Assessment
Paracetamol/Acetaminophen Risk
- Acetaminophen is a documented cause of erythema multiforme, appearing in multiple case series as an implicated drug in drug-induced erythema multiforme 2, 3.
- The mechanism involves a type IV hypersensitivity reaction, with drugs constituting one of the most common causes of erythema multiforme after infections 1, 2.
Antihistamine (Chlorpheniramine) Considerations
- While first-generation antihistamines like chlorpheniramine are less commonly reported as triggers, any medication can theoretically precipitate erythema multiforme through immune-mediated mechanisms 2.
- Antihistamines are actually used to treat erythema multiforme symptomatically, suggesting lower inherent risk 1, 4.
Phenylephrine and Other Decongestants
- Sympathomimetic decongestants like phenylephrine have minimal documented association with erythema multiforme in the available literature 1, 2.
Clinical Recognition Features
If erythema multiforme develops, you will see:
- Fixed targetoid lesions lasting minimum 7 days (not transient like urticaria which resolves within 24 hours) 5, 1.
- Symmetrical distribution predominantly on extremities, especially extensor surfaces, spreading centripetally 1.
- Possible mucosal involvement in more severe cases 1, 4.
Critical Management Algorithm
If erythema multiforme is suspected:
Immediately discontinue both Neozep and Bioflu - all potentially causative medications must be stopped 2, 4.
Assess severity:
Rule out Stevens-Johnson Syndrome - if you see widespread erythematous or purpuric macules with blisters rather than discrete targetoid lesions, this is a medical emergency requiring immediate hospitalization 1.
Investigate alternative triggers - herpes simplex virus and Mycoplasma pneumoniae are more common causes than drugs, so consider recent infections 1, 2.
Important Caveats
- The actual risk is low - while paracetamol can cause erythema multiforme, it remains a rare adverse effect given the billions of doses consumed worldwide 2.
- Never rechallenge - if erythema multiforme develops after taking these products, permanent avoidance of all components is mandatory 2, 4.
- Document the specific brand and formulation - different markets may have varying formulations of "Neozep" and "Bioflu," so knowing exact ingredients is crucial for future avoidance 2.