Low blood pressure (hypotension), often a reading below about 90/60 mmHg, is harmless and even healthy for many people if they feel well. It becomes a problem when it causes symptoms such as dizziness, lightheadedness when standing, blurred vision, fatigue, nausea or fainting, because the brain and organs may not be getting enough blood.
Common causes include dewatering, standing up quickly, certain medicines (including some blood pressure and prostate drugs), pregnancy, and heart or hormone problems. Simple measures like rising slowly, staying hydrated and increasing salt only if advised can help.
Seek urgent care if low blood pressure comes with confusion, cold clammy skin, rapid shallow breathing, a weak fast pulse or fainting, as this can signal shock or serious illness. If you faint, injure yourself, or have repeated episodes, see a doctor to find the cause and review your medicines.