Why do I feel dizzy and faint when I am upright?

This animation explains why we feel faint when we stand up or remain in an upright position for too long.

These events are made worse by certain conditions such as being in a warm, crowded, stuffy environment or when dehydrated or fatigued,

A fainting episode has no medical importance, but sometimes it results from a serious illness, condition, or disorder. Every case of fainting should be treated as a medical emergency until the cause is known and signs and symptoms have been treated.
Anybody who has recurring fainting episodes should see a doctor...Read More

Why do I feel dizzy and faint when I am upright?

This animation explains why we feel faint when we stand up or remain in an upright position for too long.

These events are made worse by certain conditions such as being in a warm, crowded, stuffy environment or when dehydrated or fatigued,

A fainting episode has no medical importance, but sometimes it results from a serious illness, condition, or disorder. Every case of fainting should be treated as a medical emergency until the cause is known and signs and symptoms have been treated.
Anybody who has recurring fainting episodes should see a doctor...Read More

What happens when I stand up?

  • Blood supply to the brain and heart reduces

Feeling unwell / lightheaded

  • Blood supply to the brain and heart reduces
  • Bloody Supply reduces further in brain and heart
  • Starting to feel mildly unwell, sweaty, lightheaded

Feeling sweaty, hot and more dizzy

  • Blood supply to the brain and heart reduces
  • Bloody Supply reduces further in brain and heart
  • Starting to feel mildly unwell, sweaty, lightheaded
  • Blood pools further into gut and legs
  • Starting to feel more dizzy, pounding heart, hot, need to sit down

About to faint, darkening vision, very unwell

  • Blood supply to the brain and heart reduces
  • Bloody Supply reduces further in brain and heart
  • Starting to feel mildly unwell, sweaty, lightheaded
  • Blood pools further into gut and legs
  • Starting to feel more dizzy, pounding heart, hot, need to sit down
  • Blood supply to brain is critically reduced, and maximal pooling occurring in the legs and gut
  • About to faint

What happens when I stand up?

  • Blood supply to the brain and heart reduces

Feeling unwell / lightheaded

  • Bloody Supply reduces further in brain and heart
  • Starting to feel mildly unwell, sweaty, lightheaded

Feeling sweaty, hot and more dizzy

  • Blood pools further into gut and legs
  • Starting to feel more dizzy, pounding heart, hot, need to sit down

About to faint, darkening vision, very unwell

  • Blood supply to brain is critically reduced, and maximal pooling occurring in the legs and gut
  • About to faint

A fainting episode may be benign, but can sometimes it results from a serious illness, condition, or disorder. Every case of fainting should be treated as a medical emergency until the cause is known and signs and symptoms have been treated.

Why do I faint? A 3 minute concise illustrative video to help you understand why you faint.

If you have ever fainted, understanding what happens when we faint is the key to being able to take appropriate simple steps to stop yourself fainting. This short illustrative video explains the main principles of fainting, and why we feel unwell with dizziness, sweatiness, feel hot and nauseous and anxious prior to fainting.

A fainting episode may have no medical importance, but sometimes it results from a serious illness, condition, or disorder. Every case of fainting should be treated as a medical emergency until the cause is known and signs and symptoms have been treated.

  • Why do I faint?
  • This is due to blood pooling in lower limbs with gravity
  • In turn, circulating blood volume is reduced in the heart, which reduces blood pressure.
  • When blood pressure reaches a critically low level, we lose consciousness (faint/blackout)