What time of day is it best to take Flomax?

It may depend on the side effects. If insomnia is a side effect, then taking it in the morning would be best. Other side effects may be better to have while you are sleeping so in that case taking it in the evening would make sense.

I agree with that-if insomnia is a result, then by all means avoid that by taking the medication at another time. The problem I have when reading information about side effects is figuring out the "cause and effect" deterministic result of a particular medication. Is my insomnia a result of, or is it enhanced by, medication X, or is it happenstance? Is the result due to a combination of several drugs, or, am I just having a bad night? The answer I suppose is keeping fairly precise notes over a period of time, and giving it an analysis. Tough to do. So, you pick an approach that seems to work, and stay with it. (A question: How much can we really rely on the list of symptoms included for each medication? Are they real, as no data of number of occurrences or conditions is ever specified. I am on Coreg, and my dosage was recently doubled. Now, I am drowsy a lot, and taking naps-not customary for me. But, is it really a result of Coreg, or, is it related to my approaching--no, flinging-toward 70?)

I had prolonged erections during the night which interfered with my sleep (a very rare side effect.) I was taking it before bed time. I'll try taking it in the AM and monitor the results.