It's a matter of life or death.

Meaning

The situation is extremely serious and could result in someone's death.

Examples

• John: We need to get this patient to the hospital immediately.
• Alice: I know! His condition is deteriorating rapidly.
• John: <b>It's a matter of life or death.</b> We need to get there as fast as possible.
• Alice: I understand. <b>It's a matter of life or death,</b> so we'll get the fastest ambulance.