I would tell them, but only if they ask you first.

When I was 19 my parents wanted me to see a psych. I went just because they wanted me to (being a teenager, I was adamant nothing was wrong with me, and I really didn't want to go at all.) My parents were even more adamant that something, in fact, was wrong with me but that they weren't sure what. So I reluctantly agreed to go.

Among many questions, the doctor asked me if I'd ever tried any prescription medications like Oxycontin or etc. I answered truthfully that no, I have never tried Oxycontin or anything like that, but I did try Adderall one time.

My friend had given one to me so I could stay awake and party. I didn't even know what it was. I asked my other friend what it was; he said he uses it sometimes to study. So I just kept it and used it for a calculus test later on that I had forgotten to prepare for. I ended up getting 100% on the test when I barely could pass them before.

The doc asked me how the Adderall affected me when I took it. I answered truthfully and said it made me feel like I actually could focus for once in my life, and that it helped me get a good score on my test.

The doc proceeded to test me for ADHD and it turned out that I had it. No one really was surprised, as I exhibited signs of it all my life growing up.

ADHD was seen mainly as an illness that only boys had when I was a child (I'm 28 now for context.) Since I'm a girl and was "gifted and talented", the doc said i should have been diagnosed with it long ago but probably hadn't been tested for it (they were right... I hadn't been) and that's why the Adderall helped me focus.

I've been taking it for 9 years now and it's been like night and day.

My point in telling this story is that yes, in the right context, it's ok to tell a doctor this. How you reacted to it when you tried it can help them with a diagnosis. if they're a good doctor, they most likely aren't going to judge you for it.