As explained in greater detail in this post, Orthostatic Intolerance (OI) is an umbrella term encompassing Neurally Mediated Hypotension (NMH) and Postural Orthostatic Tachycardia Syndrome (POTS), as well as other rarer forms of OI. Previous studies show that about two-thirds of people with ME/CFS have POTS and over 97% have NMH, so OI is something that affects everyone with ME/CFS in one way or another. Bottom line is that our bodies have trouble maintaining a steady heart rate and/or blood pressure when we are upright.
OI results from a number of dysfunctional systems (like many aspects of ME/CFS). Some of the causes behind OI that are common (perhaps even characteristic) in ME/CFS include: low blood volume, endocrine problems - the right neurotransmitters are not released in the right amounts at the right times, and poor vascular control. The end result of this combination of effects is that when we are upright, our heart rates increase and/or our blood pressure decreases and our bodies have trouble properly circulating blood to our hearts and our brains. Instead, the blood often pools in our lower extremities (some people's feet and lower legs turn a purple color after standing for even 10 minutes).
|Phenylephrine Improves OI (picture from Health Rising)|
However, they also act as vaso-constrictors throughout the body, not just in the sinuses. In this study, the researchers treated OI with phenylephrine via injection. It had a very positive effect on the patients, improving blood flow to the brain and improving their cognitive function.
This doesn't seem like big news to me because vaso-constrictors have long been used as an effective treatment for OI in ME/CFS. Midodrine is a prescription vaso-constrictor that is frequently prescribed for OI and helps many people. I personally have noticed that when I take pseudoephedrine (aka Sudafed) for allergies or a headache, it improves my OI symptoms. In fact, I sometimes take it for exactly that purpose if I have to go out in the evening, and its vaso-constricting properties do indeed improve my stamina.
What's new here is the use of phenylephrine (PE), which is a milder vasoconstrictor, to treat OI and administering it as an injection. In fact, the researchers said it didn't have the same effects when taken orally. I found that interesting because I actually take phenylephrine (just OTC Sudafed PE) every morning for my allergies, and I do find that it helps my OI a bit, though not as obviously as pseudoephedrine.
Both phenylephrine and pseudoephedrine are available over-the-counter as decongestants, though if you decide to try pseudoephedrine, you should do so under a doctor's supervision - it is a strong enough vaso-constrictor that it can sometimes cause heart palpitations. And I avoid taking either decongestant within 4 hours of bedtime or my nap because they can be stimulating.
In any case, it is good to see some research being done into currently available treatments for OI in ME/CFS. As many of us have discovered, treating OI can lead to dramatic improvements in all ME/CFS symptoms because it underlies so many of our problems. Both of my sons benefited greatly from Florinef, which allowed them both to return to school full-time when they were younger, and my older son and I have both had excellent success with beta blockers for treating OI - they have greatly improved our stamina and ability to be active.
Health Rising published a far more detailed review of this study or you can see the abstract of the actual study or the full report at these links.
What has been your experience with phenylephrine, pseudoephedrine, midodrine, or other OI treatments?