How do you know if someone has body dysmorphic disorder?

Ask your doctor: It's best to run this by a professional who will evaluate whether the person is preoccupied with an imagined defect in appearance. The person might actually have a slight anomaly but the concern shown about it is way too excessive. In addition, people with this disorder are quite distressed by their preoccupation, or they have big impairments in functioning because of it.

Psychological eval: Body dysmorphic disorder is a mental health disorder in which one becomes extremely focused on perceived body/ facial defects that don't actually exist. It can damage self esteem & quality of life. Psychological evaluation can determine if you have this condition. Cognitive behavioral therapy is a good choice for tx.