A person with social phobia fears being watched or humiliated while doing something in front of others. As a result, he or she avoids any situation in which such activity may be required.

The activity is often as mundane as signing a personal check, drinking a cup of coffee, buttoning a coat, or eating a meal. The most common social phobia is the fear of speaking in public. Many people have a generalized form of social phobia, in which they fear and avoid interpersonal interactions. This makes it difficult for them to go to work or school or to socialize at all.

Social phobias generally develop after puberty and peak after the age of 30. The cause of social phobia is unknown. There is a possibility that altered function of serotonin (a neurotransmitter involved in many behaviors) may be a factor.