A phobia can develop during childhood, adolescence or early adulthood.
They're often linked to a frightening event or stressful situation. But it's not always clear why some phobias occur.
Specific or simple phobias
Specific or simple phobias usually develop during childhood. For example, a fear of heights (acrophobia).
Simple phobias can often be linked to an early negative childhood experience. You may have been trapped in a confined space when you were young. You may then develop a fear of enclosed spaces (claustrophobia) when you're older.
It's also thought that phobias can sometimes be "learnt" from an early age. If someone in your family has a fear of spiders (arachnophobia), you may develop the same fear yourself.
Other factors in the family environment may also affect the way you deal with anxiety later in life. For example, having parents who are particularly anxious.
It's not known what causes complex phobias, such as agoraphobia and social phobia. It's thought that genetics, brain chemistry and life experiences may all play a part.
The physical reactions you experience when faced with the object of your fear are real. They aren't just "in your head".
The body reacts to the threat by releasing the hormone adrenalin. This causes symptoms such as:
- shortness of breath
- a rapid heartbeat (tachycardia)