Postural Hypotension: Why You Feel Dizzy When You Stand Up

What happens when you stand up

When you stand, gravity pulls about 500 to 800 ml (a pint or more) of blood into the legs and belly. Normally, pressure sensors in the neck and chest detect the drop within seconds. The nervous system then tightens blood vessels and speeds up the heart, so blood pressure recovers almost at once.

In postural hypotension this correction is too weak or too slow. Blood pressure falls, less blood reaches the brain, and you feel faint. Doctors usually call the condition orthostatic hypotension; the two terms mean the same thing. For the detailed medical definitions, neurogenic causes and prescription treatments, see that page. This page focuses on recognizing it and managing it day to day.

Symptoms

Symptoms typically start within seconds to 3 minutes of standing and ease when you sit or lie down:

• dizziness or lightheadedness, often described as a head rush
• blurred, dimmed or tunnel vision
• weakness, especially in the legs
• feeling sick, sweaty or confused
• an ache across the back of the neck and shoulders ("coat hanger" pain)
• fainting or near-fainting

Symptoms are usually worse:

• first thing in the morning
• after a large meal, especially high in carbohydrates
• in hot weather or after a hot bath or shower
• after alcohol
• after exercise, or standing still for a long time
• when you have been unwell or in bed for a while

Common causes

Short-term causes

• Dehydration: not drinking enough, vomiting, diarrhea, fever or heat
• Blood loss, including slow internal bleeding
• Prolonged bed rest or illness, which weakens circulation reflexes within days
• Alcohol, which widens blood vessels and causes fluid loss

Medicines

Medicines are one of the most common and fixable causes, especially in older adults:

• blood pressure drugs, particularly diuretics, alpha-blockers, nitrates and combinations
• prostate medicines such as tamsulosin and doxazosin
• erectile dysfunction drugs, especially with nitrates
• antidepressants, especially tricyclics and trazodone
• antipsychotics and Parkinson's medicines
• opioids and sedatives

Do not stop prescribed medicines without talking to your doctor. Many can be adjusted, re-timed or switched.

Long-term conditions

• Aging: blood vessels stiffen and reflexes slow
• Autonomic neuropathy from diabetes, alcohol, amyloidosis or vitamin B12 deficiency
• Parkinson's disease, multiple system atrophy and Lewy body dementia
• Heart problems such as heart failure or narrowed heart valves
• Adrenal insufficiency (Addison's disease)

Postural hypotension vs POTS

Checking at home and at the doctor's

A doctor diagnoses postural hypotension by measuring blood pressure and pulse after you have been lying down for about 5 minutes, then again 1 and 3 minutes after you stand. A drop of 20 mm Hg in the top number or 10 mm Hg in the bottom number confirms it.

If you have a home blood pressure monitor, you can record lying (or sitting) and standing readings at different times of day and bring them to your appointment. Have someone with you when you try this, in case you feel faint.

Your doctor may also check a blood count, kidney function, blood sugar and an ECG, and review every medicine you take.

What to do in the moment

If you feel dizzy after standing:

1. Sit or lie down straight away, ideally with your legs raised. Do not try to "push through" it.
2. If you cannot sit, cross your legs and squeeze your thigh and buttock muscles, or clench your fists. These counter-pressure maneuvers push blood back toward the heart.
3. Wait until you feel completely normal before trying to stand again, slowly.

Everyday habits that help

• Get up in stages: sit on the edge of the bed for a minute, flex your ankles and calves, then stand while holding something stable.
• Drink enough: around 1.5 to 2 liters (50 to 70 fl oz) a day unless your doctor has restricted fluids. A large glass of water drunk quickly before getting up can raise blood pressure for about an hour.
• Eat smaller meals and limit refined carbohydrates and alcohol.
• Avoid heat: have shorter, cooler showers and sit on a shower stool if needed.
• Raise the head of the bed by about 10 to 15 cm (4 to 6 inches), which reduces overnight fluid loss.
• Wear compression stockings or an abdominal binder if your doctor recommends them.
• Stay active: regular leg exercise improves circulation; seated or recumbent exercise is safer at first.
• Ask about salt: some people are advised to add salt, but not if you have high blood pressure, heart failure or kidney disease.

If these measures are not enough, a doctor may prescribe medicines such as fludrocortisone, midodrine or droxidopa. The orthostatic hypotension page linked above covers these in more detail.

Postural hypotension and falls in older adults

Postural hypotension is a major, often unrecognized cause of falls and hip fractures in older adults. Anyone who has fallen, feels unsteady or is on several blood pressure medicines should have lying and standing blood pressure checked. A medicine review, home safety changes and strength and balance exercises together reduce falls.

Frequently asked questions

Why do I get dizzy when I stand up?

Standing pulls blood down into your legs, and if your body does not tighten blood vessels and speed up the heart quickly enough, blood pressure drops and less blood reaches the brain. Dehydration, medicines, alcohol, heat, illness and nerve problems are the commonest reasons this response becomes too slow.

Is postural hypotension serious?

An occasional head rush is harmless. Frequent episodes can cause fainting and falls, which may lead to injuries, especially in older adults. Postural hypotension can also signal dehydration, bleeding or nerve damage, and in long-term cases it is linked to higher heart and stroke risk, so it is worth a medical review.

How can I stop feeling dizzy when I stand up?

Stand up slowly in stages, drink plenty of fluids, avoid large meals, alcohol and hot showers, and tense your leg muscles before and after standing. Ask your doctor to review medicines that lower blood pressure. Compression stockings and raising the head of the bed help some people.

Is postural hypotension the same as orthostatic hypotension?

Yes. Both terms describe a drop in blood pressure on standing. "Orthostatic" is the term used more by doctors in the US, and "postural" is common in the UK and in everyday use. The definition and treatment are the same.

Can young people get postural hypotension?

Yes. Brief head rushes are common in teens and young adults, especially when tall, dehydrated, after illness or after standing quickly. They are usually harmless. Frequent fainting or a racing heart on standing should be checked, since POTS or other causes may be involved.