For the past couple of weeks I've taken caffeine 200-300mg and Alpha Lipoic Acid 1000mg daily and have seen some mild but noticeable improvements in ED. My ED is severe so I consider any improvement to be significant.
I take both caffeine and ALA in the morning with breakfast. No side effects apart from some increased anxiety (things not easy in our household during the lockdown so I expect this to pass as life returns to normal).
The improvement is most likely due to Caffeine being, like Pentox, a mild, non-selective PDE inhibitor and ALA is a powerful anti-oxidant. I've also been drinking a lot of chamomile tea, but I doubt this is causing any effect.
I think I also read a study somewhere that state Alpha Lipoic Acid can help with nerve relates issues causing ED.
Google it if it seems like something you may be interested in.
I also found caffeine can have an effect similiar to viagra where it increases bloodflow to the penis.
I'm glad you're seeing some improvement.