Most people with phobias are scared or fear one particular thing but there are some people who are scared of a lot of things and this is called polyphobia.
Polyphobia could have been initiated by fear of a particular thing which led one to fear things associated with the thing that they fear the most. For instance, one fears having fever or pyrexiophobia, this can lead to fear of getting sick or fear of having disease, fear of needles, fear of drugs, fear of doctors, fear of hospitals, fear of dying and the list goes on and on. These people are usually mentally unstable and may have an underlying obsessive-compulsive personality disorder or sometimes may have an underlying psychotic disorder.
People with this fear are severely debilitated and are not able to function normally in society. Their fears usually paralyzes them and they do not know how to act with other people, or even how to behave with just himself or herself. They are usually introverts and loners, with no or very few friends. They also usually live alone but living alone can also scare them thus most of these people need to be institutionalized initially for them to be able to be guided by their psychiatrists.
Anti-anxiety and anti-depressant medications are usually needed in these patients, without which they are unable to function normally in society. These patients may also have suicidal ideations for they may think that they are better off dead that worrying about everything around them.
With proper guidance and treatment, most of these patients are able to get back to society and live an almost normal life.