Positives

• A CFS patient took off-brand DayQuil containing phenylephrine and found it lessened PEM, allowing them to do things without crashing and raising their baseline; they now take it daily after consulting their cardiologist Reddit.
  
  
• A CFS patient reported that phenylephrine nasal spray eliminated PEM-related nasal congestion, describing it as the only treatment with an immediate noticeable effect on their ME symptoms Reddit.
  
  

Negatives

• A CFS patient tried phenylephrine for 3 days and experienced a terrible 2-week crash, with resting heart rate dropping to the low 50s Reddit.
  
  

Hurdles & Side Effects

• Phenylephrine is not suitable for patients with high blood pressure, and the nasal spray form carries rebound congestion risk making it unsuitable for long-term use Reddit.