Specific phobia starts at an average age of about 10 years, and lasts an average of about 20 years (Carandang, 2014). So specific phobia usually starts in childhood, and lasts a long time, sometimes decades. And there is usually more than one phobia. Better prognosis is seen when specific phobia starts young- when it starts in childhood or early adolescent years, then the phobia tends to disappear in half within 5 years (Carandang, 2014).
“Chapter 3 – Specific Phobia.” Anxiety Protocol. Carandang C. 2014. Healthy Mind Research Corporation.