Positives

• A long-hauler with significant lung injury noticed distinct daily improvement after re-adding serrapeptase to nattokinase, with resting heart rate dropping from 80–90 to 55 and SpO2 increasing Reddit.
  
  
• A patient who had to stop nattokinase and serrapeptase for nose surgery developed severe muscle soreness; upon restarting, the soreness was completely gone by the next day Reddit.
  
  

Negatives

• A long-hauler with POTS, neuropathy, and tinnitus reported that nattokinase and serrapeptase made their symptoms worse, including increased neuropathy and tingling Reddit.
  
  
• A patient who initially saw promising results found that serrapeptase caused a sensation of “insides being ripped apart” with joints becoming looser Reddit.
  
  

Hurdles & Side Effects

• A commenter explained that serrapeptase can destabilize mast cells and release histamine, advising MCAS-sensitive patients to introduce it at tiny doses separated by 1–2 days Reddit.
  
  
• Users noted that serrapeptase must be taken on an empty stomach and that brand quality varies enormously, with one patient finding their second bottle did nothing Reddit.