Social phobia, such as stage fright, starts at an average age of 15.1 years, and lasts an average of 16.3 years (Grant et al., 2005). In other words, stage fright (also known as performance anxiety) usually starts in adolescence, and lasts a long time.
So if you do develop stage fright, then it could last for several years. On the bright side, if you get help and treatment for stage fright, then you can reduce your anxiety symptoms and get a better handle on the anxiety, rather than anxiety getting a hold of you. For more information and help on stage fright, please visit the rest of AnxietyBoss.com.
Reference:
The epidemiology of social anxiety disorder in the United States: results from the National Epidemiologic Survey on Alcohol and Related Conditions. Grant BF, Hasin DS, Blanco C, Stinson FS, Chou SP, Goldstein RB, Dawson DA, Smith S, Saha TD, Huang B. J Clin Psychiatry. 2005 Nov;66(11):1351 -61.