Many people with undiagnosed ADHD struggle through life, experiencing challenges that could be significantly improved with proper treatment. It's understandable to want to help a friend, colleague, or employee by suggesting they might have ADHD.
However, this should be approached very carefully.
The first important point is that ADHD symptoms can overlap with a variety of other conditions, including bipolar disorder, OCD, PTSD, and more. Unless you are a qualified mental health professional, you should avoid attempting to diagnose someone.
Making an assumption about their mental health could be harmful and counterproductive.
If you have a close enough relationship with the person, you can gently suggest they look into getting evaluated by a doctor. Emphasize that you've noticed they seem to struggle with certain issues, and a professional assessment could help them understand what's going on and access appropriate treatment. But be prepared for them to be defensive or resistant to the idea.
A better approach is to focus on the specific challenges you've observed and share how you personally cope with similar struggles as someone with ADHD.
For example, "I've noticed you seem to have a hard time staying organized. I deal with that too because of my ADHD, and finding a system that works for me has really helped."
This allows you to empathize and provide support without making assumptions.
Ultimately, the decision to seek an ADHD evaluation has to come from the individual themselves. Unless you have a very close relationship and can approach the topic delicately, it's usually best not to directly suggest someone might have ADHD. Instead, lead by example in managing your own ADHD, and be available to listen and provide encouragement if they decide to explore the possibility on their own.