Hello and welcome, It is highly likely you have orthostatic hypotension. Orthostatic hypotension happens when the blood pressure suddenly drops too low. The signs and symptoms range from mild to severe depending on the level of drop of blood pressure. It occurs when the brain and heart do not communicate with each other properly. For example, when you are standing up from a seated position blood pressure drops. But the body is not able to adjust blood pressure (especially for patients who have been bedridden for a long time and who have recently recovered from an illness) according to the body needs and it drops to that level that causes dizziness, weakness, headache, feeling tired, etc. These symptoms usually don’t last long and often goes away after sitting/lying down for a while. Dehydration, vasodilatory medicines and certain endocrine gland disorders are additional causes of the orthostatic hypotension. First of all get your blood pressure measured in both sitting and standing position. Try life-style modifications which include increasing fluid intake rich in sodium and potassium, decrease alcohol if you drink, avoid situations that trigger symptoms, such as standing up from seated position fast or standing for long periods. If the above life-style changes will not help, see you doctor for thorough health examination and tests to find out the underlying cause. I hope the above information will be helpful for you. Please, feel free to ask me if there is anything else you need to know. Thank you, Malik Amonov MD