Can a 16 year old have a phobia?

Certainly: Teenagers can have phobias. But the 16yo should be evaluated to see if the anxiety is a phobia or some other condition. Also evaluation is needed to find the best treatment.

If sudden: If a phobia appears suddenly in a previously well teen, then it should be evaluated. Pandas can cause this acutely. This is a neuropsychiatric condition secondary to an autoimmune response to strep infection. Sometimes a phobia will be triggered in a susceptible person by a psychosocial stress. Drugs and neurologic disease are also problems to rule out.