A phobia can develop during childhood or early adulthood.
They're often linked to a frightening event or stressful situation. But it's not always clear why some phobias happen.
Simple phobias
Simple phobias usually start in childhood. For example, a fear of heights (acrophobia). Sometimes they are called specific phobias.
Simple phobias can often be linked to an early negative childhood experience. For example, you may have been trapped in a confined (small or closed in) space when you were young. You may then develop a fear of enclosed spaces (claustrophobia) when you're older.
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.
Other things about your family may also affect the way you deal with anxiety later in life. For example, having parents who are very anxious.
Complex phobias
Agoraphobia and social phobia are both complex phobias. It is not known exactly what causes complex phobias. Brain chemistry, life experiences and genetics may play a part.
The physical symptoms a person has when they face the object of their fear are real. They are not 'in their head'.
The body reacts to the threat by releasing the hormone adrenaline.
Adrenaline causes symptoms such as:
- sweating
- trembling
- shortness of breath
- a rapid heartbeat (tachycardia)
Content supplied by the NHS and adapted for Ireland by the HSE