Taurine helps me the most with PEM. I gained a considerable amount of function, while crashing less. Energy levels are more stable. PEM is less frequent and recovery is faster. Symptoms (physical and mental fatigue, intracranial pressure, sensory sensitivity, cognitive impairment...) are less severe. It's by no means a cure or treatment, but the improvement allowed me to go from severe to moderate LC/mecfs. Both last year and this year, it only started having an effect when I was feeling slightly better and not during a severe crash though. 500 mg/day

I had heart pain every day for roughly three straight years. After starting taurine powder, it mostly went away. I've been taking it for two and a half months and have only had 7 days with some milder heart pain in that timeframe. I take 1.5g every morning and most nights, I take 1.5g before bed as well. I usually feel a bit drowsy an hour after taking it and it lasts for less than an hour. I haven't stopped taking it so I'm not sure if the improvements will hold once I stop but I don't plan on stopping in the near future. As with everything long covid, YMMV. I've responded poorly to other supplements that people have recommended but taurine powder feels like a winner for me.