I'm an aunt of a teenager with severe anxiety. I myself have suffered from childhood.

The biggest thing you can do is to take them seriously - and it's important they know you do. Talk openly. Don't expect the youth to be able to balance coming to terms with their illness with that of managing the pressures of everyday things like going to school. Realize that their reality has changed and it may take time to readjust. Don't be disappointed if your youth falls behind in school for instance. Once they have gathered themselves together they will reassimilate and catch up. Check your community for youth mental health programs. My neice took a year off school but was able to attend a half-day program. They did a lot of working on lifeskills and had some therapy. She is back at school this fall and thus far things look positive.