What medications have low blood pressure as a side effect?

October 11, 2025 •

5 min read

According to a study published in the National Institutes of Health, over 250 medications are known to be associated with orthostatic hypotension, where a person experiences a drop in blood pressure upon standing. Therefore, it is crucial to understand what medications have low blood pressure as a side effect to manage risks effectively.

Quick Summary

Many types of medications can cause low blood pressure, including heart medications like diuretics, beta-blockers, and nitrates, as well as psychiatric drugs such as antidepressants and antipsychotics. Other implicated medications include treatments for Parkinson's disease, BPH, and erectile dysfunction. Combining medications or taking higher doses can increase the risk of adverse effects like dizziness, fainting, and falls.

Key Points

Antihypertensives are a leading cause: Medications used to lower high blood pressure, such as diuretics, beta-blockers, and alpha-blockers, can sometimes lower it too much.
Psychiatric medications pose a risk: Antidepressants (especially TCAs) and antipsychotics can cause orthostatic hypotension by interfering with nerve signals that regulate blood pressure.
Medications for BPH and ED can induce hypotension: Alpha-blockers for benign prostatic hyperplasia (BPH) and PDE5 inhibitors for erectile dysfunction can cause low blood pressure due to their vasodilating effects.
Combination therapy increases risk: Taking multiple medications that can affect blood pressure, or mixing certain drugs like nitrates and PDE5 inhibitors, significantly increases the likelihood of hypotension.
Older adults are more vulnerable: Age-related changes in blood pressure regulation make individuals over 65 more susceptible to medication-induced hypotension.
Manage symptoms by consulting a doctor: Never stop or change a medication on your own. If you experience dizziness or lightheadedness, sit or lie down, and talk to your healthcare provider about potential adjustments.
Orthostatic hypotension is a common side effect: Many drugs, particularly those that dilate blood vessels, can cause a drop in blood pressure when moving from a seated or lying position to standing.

Common Causes of Drug-Induced Hypotension

Medication-induced low blood pressure, or hypotension, can be a temporary nuisance or a serious health risk. It occurs when a drug interferes with the body's mechanisms for regulating blood pressure. The risk is often higher for older adults, those with existing heart conditions, or individuals on multiple medications. Various classes of drugs, some unexpectedly, can cause this side effect by dilating blood vessels, reducing heart rate, or depleting fluid volume.

Medications for High Blood Pressure and Heart Conditions

Paradoxically, the most common medications for treating high blood pressure (hypertension) are also among the leading causes of low blood pressure if the dose is too high or multiple drugs are used concurrently.

Diuretics (Water Pills): These drugs, such as furosemide (Lasix) and hydrochlorothiazide (Microzide), increase urination to reduce fluid volume and lower blood pressure. Over-treatment can lead to excessive volume depletion, causing hypotension.
Beta-Blockers: Medications like metoprolol (Lopressor) and atenolol (Tenormin) slow the heart rate and reduce the force of its contractions, which can result in low blood pressure.
Alpha-Blockers: These drugs, including prazosin (Minipress) and doxazosin, relax and widen blood vessels. This action can lead to a significant drop in blood pressure, especially when standing (orthostatic hypotension).
Nitrates: Used to treat chest pain (angina), nitrates like nitroglycerin work by widening blood vessels, which can cause a drop in blood pressure.
ACE Inhibitors and Angiotensin II Receptor Blockers (ARBs): While generally less associated with orthostatic hypotension in chronic use, drugs like lisinopril and valsartan can cause a "first-dose phenomenon," where blood pressure drops significantly after the initial dose.
Calcium Channel Blockers (CCBs): These medications, including amlodipine, relax blood vessels and can affect heart rate, potentially leading to hypotension.

Medications for Neurological and Psychiatric Conditions

Several medications affecting the central nervous system can also interfere with blood pressure regulation.

Antidepressants: Older tricyclic antidepressants (TCAs), such as amitriptyline and imipramine, frequently cause orthostatic hypotension by blocking alpha-adrenergic receptors. Certain monoamine oxidase inhibitors (MAOIs) also carry this risk.
Antipsychotics: Particularly first-generation antipsychotics like chlorpromazine, but also some second-generation ones like clozapine and quetiapine, can cause hypotension by blocking alpha-adrenergic receptors.
Parkinson's Disease Medications: Drugs containing levodopa and dopamine agonists like pramipexole can cause or exacerbate low blood pressure, which is already a common symptom of the disease.
Benzodiazepines: Medications used for anxiety and sleep, such as alprazolam and diazepam, can cause a drop in blood pressure, especially in older adults.

Other Medications That Cause Low Blood Pressure

Beyond cardiovascular and psychiatric drugs, several other medications can contribute to hypotension.

Medications for Benign Prostatic Hyperplasia (BPH): Alpha-blockers like tamsulosin (Flomax) are used to relax muscles in the prostate and bladder. While often more selective, they can still cause orthostatic hypotension, especially during the first few weeks of treatment.
Erectile Dysfunction (ED) Drugs: Phosphodiesterase 5 (PDE5) inhibitors, including sildenafil (Viagra) and tadalafil (Cialis), relax blood vessel walls. This effect, which improves blood flow for erectile function, can also lower overall blood pressure. This risk is amplified when combined with nitrates.
Opioid Pain Medications: Opioids can induce hypotension through various mechanisms, including histamine release that leads to vasodilation. This is more common in older adults and when combined with other drugs.

Why Do These Medications Cause Hypotension?

Medication-induced hypotension results from several pharmacological mechanisms.

Vasodilation: Many drugs, including alpha-blockers, nitrates, and PDE5 inhibitors, relax and widen blood vessels. This reduces systemic vascular resistance and, consequently, blood pressure.
Volume Depletion: Diuretics directly reduce the body's fluid volume through increased urination. If this is not carefully managed, it can lead to dehydration and dangerously low blood pressure.
Negative Inotropic and Chronotropic Effects: Beta-blockers and certain calcium channel blockers reduce heart rate and the force of contraction. A slower, weaker heart pumps less blood, which can lower blood pressure.
Interference with Nerve Signals: Alpha-blockers and antidepressants can inhibit parts of the nervous system responsible for maintaining blood pressure, especially when changing posture from sitting or lying down to standing.

Risk Factors for Drug-Induced Hypotension

Certain factors can increase an individual's susceptibility to medication-induced hypotension.

Age: Older adults are particularly vulnerable due to age-related changes in blood pressure regulation.
Polypharmacy: Taking multiple medications that affect blood pressure, such as an alpha-blocker and a PDE5 inhibitor, drastically increases the risk.
Dosage: Higher doses of medications are more likely to cause significant blood pressure drops.
Dehydration: This can compound the effects of diuretics and other medications that reduce fluid volume.
Underlying Health Conditions: Conditions like Parkinson's disease, diabetes, and heart failure can predispose individuals to hypotension.

Comparison of Medication Classes and Hypotension Risk


Drug Class	Common Examples	Primary Mechanism	Relative Risk (Orthostatic Hypotension)
Alpha-Blockers	Prazosin, Doxazosin, Tamsulosin	Vasodilation from blocking $\alpha_1$ receptors	High, especially first dose
Tricyclic Antidepressants	Amitriptyline, Doxepin	Vasodilation from blocking $\alpha_1$ receptors	High
Antipsychotics	Clozapine, Quetiapine	Vasodilation from blocking $\alpha_1$ receptors	High, dose-dependent
Diuretics	Furosemide, Hydrochlorothiazide	Volume depletion via increased urination	Moderate to High (dose-dependent)
Beta-Blockers	Metoprolol, Atenolol	Reduced heart rate and force of contraction	Moderate
Opioids	Morphine, Oxycodone	Vasodilation, reduced sympathetic outflow	Moderate
Nitrates	Nitroglycerin	Vasodilation	Moderate
PDE5 Inhibitors (ED Drugs)	Sildenafil, Tadalafil	Vasodilation	Moderate (esp. with other hypotensive meds)
ACE Inhibitors/ARBs	Lisinopril, Valsartan	Low risk, but "first-dose" effect possible	Low to Moderate
SSRIs/SNRIs (Antidepressants)	Sertraline, Venlafaxine	Unclear, less frequent	Low

What to Do If You Experience Medication-Induced Hypotension

If you experience symptoms of low blood pressure, such as dizziness, lightheadedness, or fainting, it is important to act immediately. First, sit or lie down to prevent falls and allow your blood pressure to stabilize. Do not stand up again until the dizziness passes. Next, inform your healthcare provider about your symptoms. They may adjust your dosage, switch you to a different medication, or suggest strategies like staying well-hydrated, avoiding alcohol, and rising slowly from a seated or lying position. It is crucial not to stop or alter your medication regimen without consulting a healthcare professional first. For managing potential side effects, especially with BPH drugs like tamsulosin, taking the first dose at bedtime can mitigate the "first-dose phenomenon". In severe cases, emergency medical attention may be required, especially if you experience chest pain, confusion, or signs of shock.

Conclusion

Many medications can cause low blood pressure as a side effect, impacting patients taking drugs for heart, psychiatric, and other conditions. The risk can be influenced by drug type, dosage, and co-existing health issues. Understanding which medications can cause hypotension and recognizing the symptoms is essential for patient safety. Always consult a healthcare professional about managing side effects and never stop taking a prescribed medication without their guidance. For further reading, an authoritative source on the clinical pharmacology of antihypertensive drugs can provide deeper insight.

NCBI Bookshelf: Antihypertensive Medications

Frequently Asked Questions

The most common cause is medication used to treat high blood pressure (antihypertensives), such as diuretics, beta-blockers, and alpha-blockers, which can lower blood pressure excessively.

Yes, some psychiatric drugs can cause low blood pressure. Older antidepressants (tricyclic antidepressants) and many antipsychotics are known to cause orthostatic hypotension, a drop in blood pressure when standing.

Yes, PDE5 inhibitors used for erectile dysfunction, such as sildenafil (Viagra), can lower blood pressure by relaxing blood vessel walls. The risk is much higher if taken with nitrates or alpha-blockers.

Yes, if blood pressure drops too low, it can lead to vital organs not getting enough oxygen. Symptoms include dizziness, fainting, and potential injury from falls. In severe cases, it can lead to shock.

If you feel dizzy or lightheaded, sit or lie down immediately to prevent fainting or falling. Report the symptom to your healthcare provider, who can evaluate your dosage or suggest a different medication.

Yes, medications for Parkinson's disease, including levodopa and pramipexole, can cause or worsen low blood pressure, particularly orthostatic hypotension.

Yes, strategies include rising slowly from sitting or lying down, staying well-hydrated, and avoiding alcohol. Your doctor may also recommend wearing compression stockings or adjusting your dosage.