Positives

• In a chart review of 200 chronic-Lyme patients on Horowitz's double-dose dapsone protocol, roughly half reported a year or longer of symptom remission, including resolution of joint pain, brain fog, and fatigue PMC.
  
  
• Patients with co-infections including Bartonella reported superior improvement on 6-7 day pulses of high-dose dapsone compared to shorter pulses PMC.
  
  

Negatives

• A patient on the Horowitz dapsone-hydroxychloroquine-rifampin combo presented to the ER with drug-induced methemoglobinemia (MetHb 11.2%) and oxidative hemolysis PubMed.
  
  
• Roughly 30% of patients in clinical practice could not tolerate dapsone and had to stop, with 46 of 200 quitting Horowitz's study due to adverse reactions including severe Herxheimer flares, anemia, and rashes PMC.
  
  

Hurdles & Side Effects

• Patients must be screened for G6PD deficiency before starting and undergo regular CBC and methemoglobin monitoring, a workup most general practitioners are unwilling to manage outside a Lyme-literate clinic MDPI.