Symptoms of BDD typically begin during adolescence, most commonly by 12-13 years old.  If a child or teen obsesses about their appearance, is overly critical of perceived minor flaws and experiences severe distress as a result, they might be showing signs of body dysmorphic disorder.
BDD and School
BDD can significantly affect academic performance. Time consuming thoughts about appearance make it difficult to focus on schoolwork, and it can lead to students failing tests and having trouble concentrating in class.
Furthermore, BDD can interfere with an individual’s ability to interact with classmates and teachers, and may even prevent students from attending school at all – some teens have reported missing an entire year of school because of BDD. One study found that 18 percent of students with BDD dropped out of school entirely because their symptoms were so severe. 
Additionally, transitions, like those from middle school to high school, can be particularly nerve-wracking for those with BDD. While adjusting to a new school environment, individuals with BDD may experience an increase in their appearance-related thoughts and urges to ritualize. New classrooms, locker rooms, cafeterias, and bathrooms may cause added anxiety because they may trigger concerns about lighting or mirrors. 
Social Media and BDD
Forms of bullying like body shaming, fat shaming, and slut shaming (which can occur online and offline) can have a negative influence on body image and lead to low self-esteem, both of which are related to body dysmorphic disorder. Body shame appears to drive social isolation. In one study, 94 percent of youth with BDD described experiencing social difficulties resulting from embarrassment and shame related to their appearance. 
While social media may not cause body dysmorphic disorder, it may act as a trigger in those already genetically predisposed to the disorder, or it could worsen existing symptoms. For example, teenagers are particularly prone to developing BDD, and if “ideals” of appearance are presented to them through social media, this can trigger their development of the illness. 
Getting Help for Your Child/Teen
Acting early--before Stage 4--to address BDD will help increase the likelihood of recovery and help young people overcome their distorted self-image.
What should parents do?
- Remember that this is not a vanity issue, even though it appears to be.
- Encourage your child to participate in family activities and social gatherings.
- Remember to show unconditional love and let them talk about their struggles and experience with BDD.
- Be patient and supportive.
- Maintain a positive and close relationship.
- Remember that individuals with BDD have poor insight regarding their perceived deformity.
- Educate yourself and understand the symptoms.
- Do not lecture or push your child to do things.
- Encourage treatment by means of psychological therapy or psychiatric medication.
- Be a role model. The way you view and speak about your own appearance creates a powerful example – by accepting your appearance, weight, and any perceived flaws, you set a positive example.
- Be a good listener.
- Create a positive and supportive environment in your household.
- Expressing your own concern for your loved one can be a motivation to seek help, but can also increase guilt. Keep the focus on how your loved one would benefit from the support of a professional who truly understands the condition, rather than expressing how their illness negatively affects you. Need some tips on how to talk to your child or teen about their mental health? Check out MHA's Talking To Adolescents and Teens: Starting The Conversation.
Remember, body dysmorphic disorder is a serious mental illness. Avoid being critical and encourage your child or teen to receive professional help. Learn more about What to Do and Where to Go for help.
Also on mentalhealthamerica.net
Anxiety and Depression Association of America
Body Dysmorphic Disorder Foundation
 Bjornsson, A. S., Didie, E. R., Grant, J. E., Menard, W., Stalker, E., & Phillips, K. A. (2013). Age at Onset and Clinical Correlates in Body Dysmorphic Disorder. Comprehensive Psychiatry, 54(7), 893–903. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3779493/
 Phillips, K. A., Didie, E. R., Menard, W., Pagano, M. E., Fay, C., & Weisberg, R. B. (2006). Clinical features of body dysmorphic disorder in adolescents and adults. Psychiatry Research, 141(3), 305–314. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1592052/
 Weingarden, H., & Renshaw, K. D. (2015). Shame in the obsessive compulsive related disorders: A conceptual review. Journal of Affective Disorders, 0, 74–84. http://doi.org/10.1016/j.jad.2014.09.010