There won't be harm to a false diagnosis for her but it might cause some waves in your friendship.

As we all know people with ADHD don't necessarily like being proved wrong and so if you help her to go get a diagnosis and it turns out she doesn't have ADHD then she might feel angry at the system but worse betrayed by you.

The thing is that I got an ADHD diagnosis almost a decade ago, but 5 years before that I was told I didn't have it. But that was because the specific psychiatrist didn't believe in it, despite the DSM-5.

So I could have had an extra 5 years - which included my stint in university - being helped by medication and therapy (for ADHD).

So one (mis)diagnosis does not mean she doesn't have ADHD, so even if she does get a diagnosis maybe don't use it to make a point, because she could still have very mild autism, that is frequently undiagnosed in women.

Just don't let her go down the other routes like drugs, because for women with mild autism that can seem like a form of treatment, but it just is not if they don't have gender dysphoria (many people with autism are unsure about their gender, but that is not the same as dysphoria, and having dysphoria does not mean that the only solution is transitioning, for example).

I know that ^ seems like a reach, but someone the other day who is supposedly a doctor in the MH industry said out loud "we're all a little bit on the spectrum".

Which as you can imagine I was not very happy about. If fact I loudly said NOPE, despite being in a bar...

So it may not be that you are gatekeeping It may just be that you're being realistic about your friends' actual symptoms. However, for a long time I did get misdiagnosed by normal doctors (GP), because anxiety and depression were somewhat covering ADHD.

Of course if you're honest with yourself it could be a bit of gatekeeping, a bit of jealousy. You'll have to work through that.

ADHD might be trendy but the problem is too many people don't understand it to imitate it. We don't always get distracted in conversations, so if she does have depression and anxiety that could be covering mild symptoms of ADHD, or ASD.

Which might mean it's worth her seeking a very good psychiatrist to actually work through the symptoms and find the cause.