Although I used to think the same way, and I had a fear of medication, I was proven very wrong when untreated ADHD tore my entire life down.

Once I got on medication, it was like getting glasses for poor vision, bringing my mind into a semblance of focus and calm I never had before. I could actually do prolong stints of work or keep myself listening and not interrupting as bad, ect. Those coping tools we use before medication only go so far. But tack meds with them, and you can do pretty good. The medication is safe for the majority of us and I would recommend considering trying it. Most ADHDers do not become addicted to stimulants or have the other negative side-effects. Our brains are physiologically different.

To answer the OP, coffee didn't ever affect me until a drank a ton of it and then I got the shakes a little bit. I could drink coffee and sleep. Coffee actually soothed me too. Stimulants are similar but much more steady and don't put you in the bathroom like coffee can.

With that said, I agree with Llama Llama 44, it depends on your comorbid traits. If you have anxiety or are manic, caffeine is probably going to adversely react with those traits still.