Q: What should I do if I notice a sudden drop in my blood pressure? A: If you occasionally notice that your blood pressure level is lower than usual and you don’t experience any discomfort, there is no reason to be alarmed. However, if your blood pressure drops (even by as little as 20 mmHg) causing dizziness or fainting, you need to be aware that, in general, the possible causes include: 1) uncontrolled bleeding, such as post-traumatic splenic rupture, gastrointestinal bleeding, retroperitoneal bleeding, etc.; 2) serious infection; 3) allergic reaction; 4) postural hypotension: a change in blood pressure from a lying to a sitting position, or from a sitting to a standing position Decrease in blood pressure. This drop in blood pressure occurs quickly and can cause dizziness, light-headedness, blurred vision, and even fainting. Causes of postural hypotension include dehydration, prolonged bed rest, diabetes, heart disease, heat (e.g., prolonged sun exposure, sauna), and spinal cord injury. Some medications such as diuretics, Β blockers, calcium antagonists, renin-angiotensin converting enzyme inhibitors, antipsychotics, antidepressants, and medications for Parkinson’s disease can also cause postural hypotension. Sometimes prolonged sitting or squatting with your legs curled can also cause postural hypotension. If you experience symptoms related to hypotension, please inform your doctor and other professionals promptly so that different management measures can be taken by analyzing your condition.