Orthostatic Hypotension from Medications: Why You Feel Dizzy When You Stand Up

Standing up and feeling lightheaded isn’t just something that happens when you’re tired. For many people, especially those on medications, it’s a warning sign of something more serious: orthostatic hypotension. This isn’t just a quick spell of dizziness. It’s your body struggling to keep blood flowing to your brain when you change position - and it’s often caused by the very drugs meant to help you.

What Exactly Is Orthostatic Hypotension?

Orthostatic hypotension, also called postural hypotension, happens when your blood pressure drops too much within three minutes of standing up. The medical standard is clear: a drop of 20 mm Hg in systolic pressure (the top number) or 10 mm Hg in diastolic pressure (the bottom number). That’s not a small change. It’s enough to starve your brain of oxygen, making you feel dizzy, blurry, or like you’re about to pass out.

It’s not rare. About 5% to 30% of older adults experience it, depending on their health and meds. And up to 30% of those cases are directly tied to medications. That means for nearly one in three people with this problem, the cause isn’t aging or nerve damage - it’s something they’re taking.

Which Medications Cause Dizziness on Standing?

Not all drugs do this, but some are notorious for it. Here are the big offenders:

• Antipsychotics - Drugs like clozapine, quetiapine, and chlorpromazine can cause orthostatic hypotension in 20% to 40% of users. One Reddit user reported fainting twice after starting quetiapine for anxiety. Their blood pressure dropped from 128/82 to 92/61 in just two minutes.
• Opioids - Morphine, oxycodone, and other painkillers affect the nervous system’s ability to tighten blood vessels. About 15% to 25% of elderly patients on opioids get dizzy on standing. The risk spikes even higher if they’re also taking benzodiazepines or drinking alcohol.
• Alpha-blockers - Used for high blood pressure and enlarged prostate, drugs like doxazosin and terazosin relax blood vessels. They’re a top cause of OH in older men. Studies show a 2.8 times higher risk compared to those not taking them.
• Diuretics - Hydrochlorothiazide and furosemide reduce fluid volume. Less fluid means less blood pressure. One patient had repeated falls until their doctor removed hydrochlorothiazide - symptoms vanished in 72 hours.
• Tricyclic antidepressants - Amitriptyline and nortriptyline interfere with nerve signals that control blood pressure. Risk increases 3.2 times compared to non-users.
• Levodopa - For Parkinson’s, this drug helps movement but often crashes blood pressure. Up to half of patients on levodopa develop orthostatic hypotension.

Why Does This Happen?

When you stand, gravity pulls blood down into your legs. Normally, your body reacts instantly: blood vessels tighten, your heart beats a little harder, and your blood pressure stays steady. That’s the autonomic nervous system at work.

Medications mess with this system in different ways:

• Some block adrenaline receptors (alpha-blockers), so vessels can’t tighten.
• Others reduce fluid volume (diuretics), so there’s less blood to pump.
• Some depress the brain’s ability to send signals (antipsychotics, opioids).
• Some interfere with neurotransmitters that control vascular tone (tricyclics).

The result? Blood pools in your legs. Your brain doesn’t get enough. You feel dizzy. Sometimes, you faint.

Who’s Most at Risk?

It’s not just about the drug. It’s about who’s taking it.

• Age 70+ - Your body’s natural blood pressure control slows down. Risk jumps 3.2 times compared to younger adults.
• Taking 4+ medications - Polypharmacy is the biggest red flag. People on four or more drugs have 5.7 times higher risk of OH.
• Dehydrated or overheated - Even mild dehydration makes OH worse. Hot weather or saunas can trigger symptoms.
• Already have heart or nerve problems - Conditions like diabetes, Parkinson’s, or heart failure make the system more fragile.

What Should You Do If You Feel Dizzy Standing Up?

Don’t ignore it. Don’t assume it’s just “getting older.” Here’s what to do:

1. Check your blood pressure - Measure it while lying down, then again after standing for 1 and 3 minutes. A drop of 20/10 or more confirms orthostatic hypotension.
2. Review your meds - Bring a full list of everything you take - including supplements and OTC drugs - to your doctor. Ask: “Could any of these be causing my dizziness?”
3. Don’t stop meds on your own - Some drugs can’t be stopped suddenly. Work with your doctor to adjust dosages or switch to safer alternatives.
4. Use non-drug fixes - Drink 2 to 2.5 liters of water daily. Wear compression stockings. Stand up slowly. Avoid hot showers. Cross your legs or squeeze your thighs if you feel lightheaded.

Can It Be Fixed?

Yes - and often quickly. In 65% to 80% of cases, symptoms improve after adjusting or removing the culprit drug. One study showed 78% of patients felt better within one to two weeks of a medication change.

For some, lifestyle changes alone aren’t enough. In those cases, doctors may prescribe midodrine - a drug that tightens blood vessels. It’s not perfect, but it helps about 65% of people who still struggle after other steps.

Why This Matters More Than You Think

This isn’t just about feeling dizzy. Orthostatic hypotension increases your risk of:

• Falls - 15% to 30% higher chance, especially in older adults.
• Bone fractures - Hip fractures from falls can be life-changing.
• Cognitive decline - Reduced blood flow to the brain over time may contribute to memory problems.
• Mortality - Studies show a 24% to 32% higher risk of death over 10 years.

And the cost? In the U.S. alone, OH-related falls cost Medicare $31 billion in 2022. About a third of those cases are directly linked to medications.

What’s Changing in Medicine?

Doctors are catching on. The American Geriatrics Society’s Beers Criteria now lists 12 high-risk medications for older adults. Since 2020, the FDA requires drug labels to warn about OH risk if it happens in 5% or more of clinical trial participants.

Newer drugs are being developed with OH in mind. Seven pharmaceutical companies are testing alpha-1A selective agonists - drugs that treat the main condition without crashing blood pressure. And research is underway to predict who’s most at risk using genetic markers.

Final Thought: Your Meds Aren’t Always the Cure

Many people think taking more pills means better health. But sometimes, the solution is taking fewer. Orthostatic hypotension is one of the most preventable side effects out there. If you’re dizzy when you stand, it’s not normal. It’s a signal. Talk to your doctor. Get your blood pressure checked. Review your meds. You might find that the fix is simpler than you think - and it could save you from a fall, a hospital stay, or worse.