@Mary , we both feel similarly about supplements, after spending so much time and energy and little to show for it. However, liposomal glutathione seems to be one of the few supplements that does make a difference. It's a bit pricey, and for that reason, he uses it sparingly. He requires 3 doses to get an effect, so it might take some experimenting to find out how much you need to see improvement (if it works for you).
He's a bit inconsistent in terms of what does or doesn't cause PEM, but there are some triggers that are very likely going to give him problems (working on his car in the hot Florida sun, for example). One of the first times he was testing the glutathione, he took his 3 doses, carried a really heavy car battery down a flight of stairs to his car, spent about 1/2 hour prying out the dead battery, and putting the new one in. All in the blazing mid day sun. Afterward, he spent a couple hours actively doing stuff in the apartment, like brewing beer and cleaning guns.
On his best day, he could do either the beer or cleaning guns but would get tired an need to rest afterward. No way could he do all of that stuff. He wasn't lifting weights at the gym, or anything extreme, but he was able to do a lot more than on his best days. He's used it multiple times since that early test, and generally has the same result. So he uses it as a PEM preventative. I don't remember if he's taken it after getting PEM. The only reason he doesn't use it everyday is the cost, since he needs 3 doses at a time, and the tiny bottle is $40. If we had more money, I'd buy it by the case.
We are currently doing an experiment using Ketone salts. He had some interesting results using them in conjunction with and without a keto diet (he's done a keto diet before and didn't have improvements in CFS) but taking the actual Ketone salts actually got rid of his PEM, which we found kind of shocking. We have to see if this is repeatable or just a one-time thing. Once we have some more experience and data, I will post about this on PR, and I will try to remember to tag you.