I’m on a dose of 6 mg, which I understand from my doctor is one of the higher doses, but she has some patients who are successful on an even higher dose. I think I only read one report with patients on 6 mg, so that’s as high as I decided to go because I don’t really notice a difference over 4.5 (but nothing worse either so I’m finishing the 90-day supply).

You might consider if you want to try a higher dose and if not, for most medications if there’s not an improvement in 3-6 months (I’m thinking of my rheumatology medication), it’s a no-go. For me the difference was slight; I only noticed improvement in fatigue. When I stopped taking it, I noticed. That’s a possibility too. If you take a medication “holiday” and you still feel the same, maybe that tells you it’s not the right fit?

I just started 3 mg of Naltrexone
yesterday. I am diagnosed Long Covid with fatigue, insomnia, and PEM. I find that sleep is the critical factor for energy. What time of day do you take it? Morning or Evening?

Just want to share my experience.
I started off at a conservative 1.5mg dose, felt nothing, so doubled it after two weeks. I then felt perhaps just a tiny bit worse, if anything, but with my cooperative physician's assistant, got a new prescription at 4.5mg. After a few days I felt slightly "drugged", almost as if I had drunk a small amount of alcohol--something I cannot do during my nearly one year of LC--so quit the regimen altogether.
I also took oral NAD+ alongside the LDN, as one of the large studies had done, in their case via injection.
I'm continuing the NAD+, but can't say I'm feeling any effect from that.
Should also state that, given the astounding variety of the how LC presents, in my case it's almost solely fatigue, with some "brain fog", so I consider myself comparatively fortunate.
Want to mention, too, for the originator of this thread who suffered a bad rash, that this can be a serious contraindication for many medications, although I'm unsure about that for LDN specifically.