Table 9 Impressions on the effects of 6-MSITC treatment by patients with ME/CFS (patient number)

(S1) I used to feel heavy when moving my body, e.g., raising my arms. But now I feel lighter. I feel that gravity has become lighter. I used to have a clogged feeling in my head and my headache became worse after exertion, but now I feel fine even after working for the same amount of time (1 h or so). Previously, I couldn’t find appropriate words and put them together well when I thought about something, and the more I thought about it, the hotter my head and upper back became. But now that I can put together words, the feeling of burning has subsided. In the past, my head was always dull and foggy, but now I have more time when my brain fog is clear

(S2) It was effective for inflammation in my mouth. I always had pain in my mouth due to stomatitis. I also used to feel that my tongue was swollen. But these symptoms have subsided. Post-nasal drip became easier to clear and now it is less congested and stuffy in my throat

(S3) I'm still drowsy and unable to concentrate in the morning, as before, but in the afternoon my head is clearer, and my body is easier to move. I used to be sick in bed for 1 to 4 days when there was a sign of a crash, but now I can recover by bed rest for half a day or several hours. I've become stronger. The pain has changed from general to localized

(S4) I can walk longer than before

(S5) I became a little more active in the daytime. I became able to move a little longer

(S6) In the past, there was always a haze in my head, and I felt like the electrical signal from my brain was cut off and my brain didn’t work. But now, I can put my thoughts together. It was difficult to find words but that has become easier. I became able to make notes in a notebook while reading the material. I became able to concentrate longer on reading books and summarizing materials (from about 10 min to about 1 h). My head is starting to work better although I still have a light fog. I feel like I'm sleeping deeply

(S7) Previously, my head was foggy all the time and my thinking ability and memory were zero, but now I feel like they have become clearer. Compared to when I was healthy, it's still a long way off, but it has improved considerably, and it has become easier to live. I became able to understand conversations and come up with more words. My fatigue lessened from around the second month and the number of days at level 7 has increased from what used to be 8–10. It was a great help!!

(S9) The dullness became better although the time of improvement is still short

(S10) I am more motivated. I have more things I want to do than before. I have an appetite

(S11) I can now do multiple things at the same time such as cooking because my brain fog decreased. Previously, I couldn't remember even 3 or 4 digit numbers, but now I can. I used to be very tired when I woke up with a clear dream, but now I can sleep better with less dreaming. My constipation has improved. I couldn't listen to music because it was mixed with words and noise, but now I can. I couldn’t move my fingers with fine control, but now I can. I no longer collide with people or things when I walk

(S13) I didn't feel clear in my head and couldn't react immediately when someone talked to me, but I can think and react faster than before

(S15) I used to feel strong fatigue. But after taking 6-MSITC, I became less tired

(S16) To be honest, I didn't feel much change

(S17) My frequency of low-grade fever has decreased. My fatigue level was also reduced a little

(S18) I always felt hazy in my brain, and it was challenging, but it became clearer and easier to think about things. By becoming clear, I became able to clearly understand where and how strong and painful my symptoms were, instead of feeling somewhat dull, heavy, and in pain