Low BP (Hypotension) — Symptoms, Causes, When to Worry
Open this article in the interactive app
Low blood pressure (hypotension) means your blood pushes against your artery walls with less force than normal. In general, a reading below 90/60 mmHg is called low blood pressure. Here is the part that surprises people: low numbers alone are not the problem — symptoms are. Many healthy people, especially young people and athletes, live comfortably at 90/60 with no complaints at all.
What does it mean?
Blood pressure is written as two numbers, for example 120/80. The top number (systolic) is the pressure when your heart beats; the bottom number (diastolic) is the pressure between beats. It is measured in mmHg (millimeters of mercury). One reading by itself isn't enough to judge — your doctor reads your numbers against your normal baseline and whether you have symptoms, not against a fixed line alone. For a trustworthy home reading: rest 5 minutes first, sit with your back supported and your arm at heart level, don't talk during the reading, and take two readings a minute apart.
Common causes
- Symptoms of low BP
Dizziness or lightheadedness, especially when standing up; fainting (passing out); blurred or narrowing vision (“tunnel vision”); nausea; fatigue or unusual weakness; difficulty concentrating; confusion in severe cases; cold, clammy, pale skin with rapid or shallow breathing — these are shock signs, a medical emergency. - Common causes
Dehydration — one of the commonest causes: heavy sweating, vomiting, diarrhea, or simply drinking too little water. Blood loss — from an injury, heavy periods, or slow internal bleeding. Medications — blood-pressure drugs, diuretics (“water pills”), and some antidepressants and Parkinson's medicines. Heart problems — very slow heart rate, heart valve problems, or heart failure. Gland (endocrine) disorders — underactive thyroid, adrenal insufficiency, or low blood sugar. Pregnancy — BP often dips during the first 24 weeks. Severe infection (sepsis) — needs hospital care. - Common types
Orthostatic (postural) hypotension — a sudden drop within 3 minutes of standing, defined as a fall of 20 mmHg or more systolic or 10 mmHg or more diastolic. Postprandial hypotension — BP dropping 1 to 2 hours after eating; most common in older adults. Neurally mediated hypotension — fainting after standing for a long time; most common in young people.
When to worry
Seek urgent medical care
Get urgent medical help if low BP comes with: fainting — especially during exercise or while lying down; chest pain, or a pounding or irregular heartbeat along with dizziness; confusion or altered consciousness; cold, clammy, pale skin with rapid breathing (signs of shock) — call 1122 immediately; no recovery after lying down with your legs raised; an injury from a fall caused by fainting.
What a doctor checks
Your doctor will look for underlying causes — anemia, a heart condition, a hormonal (endocrine) disorder, or a side effect of your current medicines. Tell your doctor about all medicines you take. You can also check your heart rate at home and share the reading with your doctor.
Prevention & practical tips
- Sit or lie down at the first sign of dizziness; raise your legs if you can.
- Move slowly when getting up — sit on the edge of the bed first, then stand.
- Drink enough water through the day, especially in heat or after sweating.
- Eat smaller, more frequent meals if you feel faint after eating.
- Tell your doctor about all medicines you take — some may be lowering your BP.
- Avoid standing up suddenly, standing still long in heat, and alcohol.
- Never change or stop prescribed medicines on your own.
- Avoid driving or climbing heights while you feel dizzy.
Questions to ask your doctor
- What blood pressure reading counts as low for me?
- Could my dizziness be caused by my medicines?
- Do I need tests for my low blood pressure?
FAQs
This is called orthostatic (postural) hypotension. The moment you stand, gravity pulls blood toward your legs — and if your body doesn't compensate fast enough, pressure dips briefly and you feel dizzy. The fix is simple: rise slowly, especially when getting up from bed or a chair.
Yes — it's one of the most common causes. Heavy sweating, vomiting, diarrhea, or simply not drinking enough water shrinks your total blood volume, and blood pressure falls with it.
If dizzy spells keep interrupting your daily life and there's no obvious reason, book a checkup. Your doctor will look for underlying causes — anemia, a heart condition, a hormonal (endocrine) disorder, or a side effect of your current medicines.
References
Mayo Clinic: Low blood pressure (hypotension)
Supports the 90/60 threshold, symptoms, causes, and types in this article.
- Mayo Clinic — Low blood pressure (hypotension): symptoms and causes.
- Cleveland Clinic — Low blood pressure (orthostatic hypotension).
- AAFP — Orthostatic Hypotension: A Practical Approach.
Only articles marked Reviewed ✓ with a date have passed Dr. Umer's medical review.
How this article was reviewed
- Written by: Dr. Muhammad Umer Farooq, MBBS — October 2026
- Medical review: Completed by Dr. Muhammad Umer Farooq, MBBS — October 2026. All medical content was provided and verified by Dr. Umer.
- Found an error? Tell Dr. Umer by email