Nitro-Dur Drug Interactions: What to Avoid and What to Tell Your Doctor

Nitro-Dur (nitroglycerin transdermal patch) has some of the most important drug interaction warnings of any common cardiac medication. Some of these interactions can be life-threatening. Before starting Nitro-Dur — or before adding any new medication to your regimen — understanding these interactions could save your life.

CRITICAL: Never Combine Nitro-Dur With PDE-5 Inhibitors (ED Medications)

This is the most important drug interaction warning for Nitro-Dur. Combining nitroglycerin with phosphodiesterase-5 (PDE-5) inhibitors causes a synergistic vasodilatory effect that can drop blood pressure to dangerously low levels — potentially causing heart attack, stroke, or death. This combination is absolutely contraindicated.

PDE-5 inhibitors include:

Sildenafil (Viagra, Revatio) — Used for erectile dysfunction and pulmonary arterial hypertension

Tadalafil (Cialis, Adcirca) — Also used for benign prostatic hyperplasia (BPH)

Vardenafil (Levitra, Staxyn) — Used for erectile dysfunction

Avanafil (Stendra) — Used for erectile dysfunction

If you're on Nitro-Dur and experience an angina attack: you cannot use sublingual nitroglycerin without first removing your patch. And you absolutely cannot take a PDE-5 inhibitor for any reason while using a nitroglycerin patch. If you need help with erectile dysfunction and are on Nitro-Dur, talk to your cardiologist — other options may exist.

CRITICAL: Never Combine With Riociguat (Adempas)

Riociguat (Adempas) is a soluble guanylate cyclase stimulator used for pulmonary arterial hypertension. Like PDE-5 inhibitors, it amplifies nitroglycerin's vasodilatory effects. The combination is contraindicated and can cause severe, life-threatening hypotension.

Avoid Ergot Alkaloids (Ergotamine, DHE)

Ergot alkaloids — including ergotamine and dihydroergotamine (DHE), used to treat migraines — directly counteract nitroglycerin's vasodilatory effects and can increase angina risk. These medications are also contraindicated with Nitro-Dur.

Moderate Interactions: Use With Caution and Medical Supervision

Antihypertensive medications: Beta-blockers, calcium channel blockers, ACE inhibitors, and ARBs all lower blood pressure. Combined with nitroglycerin, the additive effect can cause excessive hypotension. Your doctor will monitor your blood pressure closely.

Diuretics (water pills): Furosemide (Lasix), hydrochlorothiazide, and other diuretics lower blood pressure and can increase dehydration risk — which makes nitroglycerin-induced hypotension worse.

Heparin: IV nitroglycerin (not transdermal) is known to affect heparin requirements in hospital settings, but this is primarily a concern with intravenous administration.

Alcohol: Alcohol is a vasodilator. Combined with nitroglycerin, it can amplify dizziness, lightheadedness, and the risk of fainting. Limit alcohol use while wearing a Nitro-Dur patch.

Antipsychotic medications: Some antipsychotics (including iloperidone) have blood-pressure-lowering effects that may be additive with nitroglycerin. Your doctor should review your full medication list.

What to Tell Every Doctor and Pharmacist

Because the interaction with PDE-5 inhibitors can be fatal and because many people see multiple doctors, it is critical that you tell every provider and pharmacist you see that you use a nitroglycerin patch. This includes:

Your cardiologist (who prescribed it)

Your primary care doctor

Any specialist (urologist, pulmonologist, neurologist)

Emergency room or urgent care staff — they may consider nitroglycerin or ED medications for various conditions

Your pharmacist — who can screen for interactions with any new prescription

Dentist and oral surgeon — anesthesia protocols can be affected by nitroglycerin

Lab Interactions

Nitroglycerin may interfere with certain lab tests, including blood cholesterol tests. Make sure all lab personnel and your doctors know you use this drug before any blood draws.

Also read: Nitro-Dur Side Effects: What to Expect | What Is Nitro-Dur? Uses and Dosage