Recent Blog Articles
The popularity of microdosing of psychedelics: What does the science say?
Pouring from an empty cup? Three ways to refill emotionally
Is pregnancy safe for everyone?
New pediatric guidelines on obesity in children and teens
Screening tests may save lives — so when is it time to stop?
Natural disasters strike everywhere: Ways to help protect your health
The case of the bad placebo
Do we feel pain more at night?
If you use cannabis, do it safely
Time for a diabetes tune-up
Blacking Out, Fainting, or Loss of Consciousness
Welcome.
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.
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
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise
I'd like to receive access to Harvard Health Online for only $4.99 a month.
Sign Me UpAlready a member? Login ».
Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Free Healthbeat Signup
Get the latest in health news delivered to your inbox!
