What Medications Will Cause Low Blood Pressure? A Comprehensive Guide

October 11, 2025 •

3 min read

Low blood pressure, or hypotension, is a common and sometimes dangerous side effect of many medications. In older adults, in particular, drug-induced postural hypotension is a significant risk. This guide explains what medications will cause low blood pressure and what you should know to stay safe.

Quick Summary

A variety of prescription drug classes, including antihypertensives, antidepressants, ED medications, and opioids, can cause hypotension. The risk is elevated with higher doses, age, and drug combinations. Knowing the triggers and recognizing symptoms like dizziness and fainting is crucial for patient safety.

Key Points

Antihypertensive Drugs: Medications prescribed to lower high blood pressure, such as beta-blockers, alpha-blockers, and diuretics, are the most common causes of medication-induced hypotension.
Diverse Drug Classes: Beyond blood pressure medications, other drug classes like antidepressants (TCAs and some SSRIs), ED drugs (PDE5 inhibitors), opioids, and Parkinson's medications can also cause low blood pressure.
Orthostatic Hypotension: A frequent side effect is orthostatic (postural) hypotension, which is a drop in blood pressure upon standing, leading to dizziness or fainting.
Synergistic Risk: The risk of developing hypotension increases significantly when multiple medications with blood pressure-lowering effects are taken together.
Initial and Dose Changes: Hypotension is a particular risk when first starting a new medication, increasing a dose, or in older adults due to age-related physiological changes.
Professional Guidance: It is critical to consult a healthcare provider if you experience symptoms of low blood pressure and never adjust medication dosages without professional advice.

Antihypertensive Medications

Antihypertensive medications, designed to lower blood pressure, can sometimes cause it to drop too low, especially when starting a new drug, adjusting a dose, or taking multiple medications.

Diuretics (Water Pills) Diuretics like furosemide and hydrochlorothiazide reduce blood volume by increasing urination, which lowers blood pressure. Excessive use or dehydration can lead to a significant drop in blood pressure.

Beta-Blockers Beta-blockers (e.g., metoprolol, atenolol) lower blood pressure by slowing the heart rate and reducing the force of contractions. Dizziness and fatigue are common side effects as the body adjusts and can indicate low blood pressure.

Alpha-Blockers Alpha-blockers, such as prazosin and doxazosin, relax blood vessel muscles, allowing for improved blood flow and reduced blood pressure. They are known to cause first-dose hypotension, a sudden pressure drop after the initial dose.

ACE Inhibitors and ARBs ACE inhibitors (e.g., lisinopril) and ARBs (e.g., valsartan) lower blood pressure by blocking the hormone angiotensin, which normally constricts blood vessels. While generally well-tolerated, they can cause hypotension.

Calcium Channel Blockers Calcium channel blockers (e.g., amlodipine, verapamil) relax and widen blood vessels by preventing calcium entry into muscle cells. This can sometimes lead to lightheadedness and dizziness if blood pressure is lowered too much.

Non-Cardiovascular Medications

Many medications not primarily for blood pressure can still cause hypotension as a side effect.

Medications for Erectile Dysfunction (ED) ED medications (PDE5 inhibitors like sildenafil) relax blood vessels to enhance blood flow. Combining them with nitrates can lead to a dangerous, sudden drop in blood pressure.

Antidepressants Some antidepressants, including older classes like TCAs and MAOIs, can cause orthostatic hypotension by affecting blood pressure regulation. SSRIs have also been linked to an increased risk of postural hypotension in older adults, particularly early in treatment.

Opioid Pain Relievers Opioids such as morphine can cause hypotension, including orthostatic hypotension, especially in older patients.

Parkinson's Disease Medications Medications for Parkinson's disease, including levodopa, can lower blood pressure. The disease itself can also contribute to blood pressure regulation issues.

Antipsychotics Certain antipsychotics, such as chlorpromazine and clozapine, can cause orthostatic hypotension, particularly at higher doses.

Factors Increasing Hypotension Risk

Several factors can increase the risk of medication-induced low blood pressure:

Drug Combinations: Taking multiple medications that lower blood pressure simultaneously significantly increases the risk.
Higher Doses: The likelihood of hypotension generally increases with higher medication doses.
Age: Older adults are more prone to medication side effects like orthostatic hypotension due to age-related changes in the cardiovascular system.
Underlying Conditions: Existing health issues like heart problems or dehydration can make individuals more susceptible to medication-induced hypotension.

Comparison of Medication Classes and Hypotension Risk


Medication Class	Mechanism Affecting BP	Risk of Hypotension	Common Examples
Diuretics	Reduces blood volume by increasing urination	High, especially with high doses or dehydration	Furosemide, HCTZ
Beta-Blockers	Slows heart rate and force of contraction	Moderate to high, especially early in treatment	Metoprolol, Atenolol
Alpha-Blockers	Relaxes blood vessel walls	High, particularly first-dose orthostatic hypotension	Prazosin, Doxazosin
ACE Inhibitors/ARBs	Blocks hormone that narrows vessels	Moderate, typically in the first year of treatment	Lisinopril, Valsartan
Calcium Channel Blockers	Relaxes heart and vessel muscles	Moderate, especially non-dihydropyridines	Amlodipine, Verapamil
PDE5 Inhibitors (ED)	Relaxes blood vessels	Moderate, higher risk with nitrates	Sildenafil, Tadalafil
Antidepressants (TCAs/SSRIs)	Interferes with blood pressure regulation	Moderate to high, especially in older adults	Amitriptyline, SSRIs
Opioids	Can suppress central nervous system	Moderate, increases with higher doses	Morphine, Oxycodone
Parkinson's Meds	Lowers dopamine levels, affecting regulation	Moderate to high	Levodopa, Pramipexole

When to Seek Medical Attention

Recognizing symptoms of medication-induced hypotension is crucial to prevent complications like falls. Contact your healthcare provider if you experience:

Dizziness or lightheadedness
Blurred vision
Nausea or fatigue
Fainting (syncope)
Rapid, shallow breathing
Confusion

Conclusion

Various medications, including antihypertensives, ED drugs, antidepressants, and opioids, can cause low blood pressure. Factors such as age, dehydration, and drug interactions increase this risk. It's essential to be aware of symptoms like dizziness and fainting and to report them to your healthcare provider, who can adjust your medications for safety and effectiveness. For more information on drug interactions affecting blood pressure, consult resources like the National Institutes of Health.

Frequently Asked Questions

Alpha-blockers, like prazosin and doxazosin, are particularly known for causing 'first-dose hypotension,' a sudden and significant drop in blood pressure after the first dose.

Yes, certain antidepressants can cause hypotension. Older classes like tricyclic antidepressants (TCAs) are known offenders, and some studies show that selective serotonin reuptake inhibitors (SSRIs) can increase postural hypotension risk in older adults, especially during the first month of treatment.

Yes, medications for ED, known as PDE5 inhibitors (e.g., sildenafil, tadalafil), can cause low blood pressure. The risk is especially high and potentially dangerous if they are combined with nitrates for chest pain.

Some Parkinson's disease medications, including levodopa and dopamine agonists like pramipexole, can cause low blood pressure. This effect can be compounded by the disease's natural impact on blood pressure regulation.

Common symptoms include dizziness, lightheadedness, blurred vision, nausea, fatigue, and feeling faint. The symptoms often occur or worsen when standing up, a condition known as orthostatic hypotension.

Your risk increases with higher medication doses, when combining multiple blood pressure-lowering drugs, and as you get older. Other factors like dehydration and underlying medical conditions also play a role.

If you experience symptoms like dizziness or lightheadedness, you should sit or lie down immediately. Do not stop taking your medication, but contact your healthcare provider to report the symptoms. They may need to adjust your dose or switch medications.