Postural Hypotension

Key facts

• Postural hypotension (also called orthostatic hypotension) is a sudden fall in blood pressure, at least 20 mmHg systolic, within three minutes of standing from sitting or lying down.
• It reduces blood flow to the brain, causing lightheadedness, blurred vision, or a brief faint, and is especially common in older adults and people taking certain heart and blood pressure medicines.
• Dehydration is the most frequent trigger; prolonged bed rest, diabetes, Parkinson's disease, alcohol, and large meals can also provoke a drop.
• Simple measures, rising slowly, staying hydrated, wearing compression stockings, help most people; midodrine is an option when lifestyle changes aren't enough.

Why it happens

Standing up normally triggers reflexes that tighten blood vessels and speed up the heart to keep blood pressure steady. In postural hypotension, this reflex response is too slow or too weak, so blood pools in the legs and pressure falls before the body can compensate. Doctors typically confirm the diagnosis by measuring blood pressure while lying down and again after standing for one and three minutes.

What brings it on

Dehydration is the most frequent trigger. Other contributors include prolonged bed rest, diabetes, Parkinson's disease, and some heart and blood pressure medicines or diuretics. Alcohol and large meals can also provoke a drop in blood pressure on standing.

Managing the condition

Simple self-care helps a great deal: rise slowly from bed or a chair, stay well hydrated, wear compression stockings, and avoid standing still for long periods. When lifestyle measures aren't enough, midodrine, an alpha-adrenergic agonist that tightens blood vessels, is a recognised option for raising standing blood pressure. Frequent or prolonged fainting needs medical assessment to rule out an underlying cardiac or neurological cause.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.