what causes low blood pressure
Last updated September 6, 2026.
**Low blood pressure usually happens for one of four reasons: too little fluid in your circulation, a heart that is not pumping strongly, blood vessels that stay too relaxed, or a medicine that lowers pressure more than intended.** A reading under 90/60 mm Hg is often called low, but the number matters less than how you feel. Many healthy people, especially younger adults and athletes, run low with no symptoms and need no treatment. Dehydration, blood loss, pregnancy, hormone conditions such as thyroid or adrenal disease, heart rhythm problems, and severe infection all reduce pressure, and drugs like diuretics, nitrates, alpha blockers, and some antidepressants add to the drop. Short dips when you stand up, called orthostatic hypotension, get more common with age, bed rest, hot weather, alcohol, and large meals. Drinking enough fluid, standing up slowly, and reviewing your medicine list with a clinician resolve most everyday cases.
What to do
- Check your medicine list: Bring every prescription, patch, and supplement to your clinician, since dose changes are the most fixable cause of low readings.
- Rehydrate first: Drink water steadily through the day and add more during illness, heat, or hard exercise, when fluid losses climb fastest.
- Stand up in stages: Sit on the edge of the bed for a few seconds, then rise slowly, and hold something steady until any lightheadedness passes.
- Track your numbers: Log home readings with the time, your position, and any symptoms so patterns tied to meals or medicines become visible.
- Watch for warning signs: Fainting, confusion, chest pain, shortness of breath, or cool clammy skin means you need emergency care now.
- Ask about the cause: A new drop in pressure with no clear trigger deserves a clinician visit to check your heart, blood count, and hormone levels.
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