Blacking Out, Fainting, or Loss of Consciousness


The two main reasons for blacking out are insufficient blood flow to the brain and abnormal electrical activity within the brain (a seizure).

While both of these sound scary, in reality most episodes of blacking out are not related to life threatening health problems.

This guide is designed to provide insight into why you passed out. It is not a diagnostic tool or a substitute for evaluation by a health professional.

The questions are ones your doctor is likely to ask you. Your answers provide a path to better understanding of the common reasons for losing consciousness.

Let's begin.

Certain situations demand emergency medical care.

Do any of the following apply to you?

- Chest pain or shortness of breath before or after you passed out

- Bloody or black stools

- Severe headache

- Recent blow to the head

- A heart condition

Yes, one of those applies to me.

No, none of those apply to me.

That's good. But even without these symptoms, you might need rapid medical evaluation.

You always need to contact your doctor immediately if:

- This has never happened to you before

- Your reason for blacking out in the past was never diagnosed

- This most recent episode is not exactly the same as the past episodes for which you did have a diagnosis

- You are surprised that it has happened again at this time

Do any of the above apply to you?

Yes, one or more do apply to me.

No, none of those apply to me.

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