Positives

• A patient with ME/CFS and asthma noticed a “significant improvement in sleep quality” from the first day of taking zileuton, with their fitness tracker confirming better rest during sleep Reddit.
  
  
• For someone managing MCAS, zileuton effectively reduced “wheezing and abdominal cramping” by blocking LTC4 production Reddit.
  
  

Negatives

• Patients on zileuton commonly need monthly liver enzyme monitoring for the first 3 months and quarterly thereafter, and roughly 4-5% of users develop ALT elevations to 3x the upper limit of normal in the first 3 months requiring discontinuation PubMed.
• Patients on zileuton commonly report abdominal pain, nausea, and upper respiratory infections, on top of the liver enzyme monitoring burden Drugs.com.
• Patients on zileuton are warned the drug may cause agitation, irritability, depressed mood, sleep disturbances, and suicidal thoughts, leading some asthma and MCAS patients to stop the drug despite symptom benefit FDA label.

Hurdles & Side Effects

• One individual taking zileuton alongside other medications reported experiencing “dry heaving in the morning,” which also affected their appetite Reddit.