Hypotension in a patient experiencing sepsis is caused by the body's inability to maintain adequate blood pressure. This occurs due to the sepsis-induced reduction in vascular volume, which leads to a decrease in cardiac output and a decrease in systemic vascular resistance. Additionally, sepsis can cause vasodilation, which further reduces blood pressure. Other contributing factors include reduced blood volume, changes in electrolytes, and the release of inflammatory mediators. Treatment typically involves aggressive fluid resuscitation, vasopressor medications, and monitoring of vital signs.