Orthostatic intolerance

Orthostatic intolerance is when your body has trouble adjusting to being in an upright position, like when you're standing or sitting after lying down for a while. It means that when you stand up, your body has a hard time keeping the blood flowing to your brain and other important organs.

When you stand up, your body needs to work harder to keep the blood flowing to your brain because gravity is pulling it downward. Usually, your body adjusts quickly by making your heart beat faster and your blood vessels constrict (get smaller) to keep the blood flowing. But sometimes, your body doesn't respond well to being upright, and you might start to feel lightheaded, dizzy, or even faint.

There are different types of orthostatic intolerance, but one common type is called postural orthostatic tachycardia syndrome (POTS). In POTS, your heart rate increases a lot when you stand up, but your blood pressure may drop or stay the same. This can cause symptoms like fatigue, brain fog (difficulty concentrating), headaches, nausea, and more.

Doctors don't know exactly why some people develop orthostatic intolerance or POTS, but it can be related to certain medical conditions or medications. Treatment might involve lifestyle changes (like drinking more water, eating salt, and moving slowly when standing up), medications to improve blood flow or heart rate, and/or physical therapy to slowly increase activity levels.