Blood phobia (also, AE: Hemophobia, BE: Haemophobia) is the extreme and irrational fear of blood. Acute cases of this fear can cause physical reactions that are uncommon in most other fears, specifically vasovagal syncope (fainting). Similar reactions can also occur with trypanophobia and traumatophobia. For this reason, these three phobias are categorized as "blood-injection-injury phobia" by the DSM-IV. Some early texts refer to this category as "blood-injury-illness phobia."
Blood phobia is often caused by direct or vicarious trauma in childhood or adolescence. There is also a genetic component to blood phobia.
In patients with vasovagal blood phobia, patients who are successfully treated with psychological interventions are seen as unique. In contrast, many behavioral techniques useful in mitigating vasovagal syncope, such as applying tension to the muscles in an effort to increase blood pressure, are helpful to patients with blood phobia. Medical devices, such as pacemakers
, are also used to treat patients with blood-phobia.