Social phobia can be manifested by symptoms such as blushing, hand tremors and nausea, often accompanied by low self-esteem and fear of criticism. It is possible that low self-esteem is a personality factor that triggers social phobia, but it is not necessarily the only trigger. Other factors may be involved in the development of the phobia: other factors such as stressful life events, biology, neurobiochemistry, etc. may combine to cause it.