Nitro-Dur Side Effects: What to Expect and When to Call Your Doctor

Starting Nitro-Dur (nitroglycerin transdermal patch) can come with some adjustment period side effects — most of them manageable and temporary. Understanding what to expect helps you stay the course with your cardiac treatment and know when a symptom actually warrants a call to your doctor.

The Most Common Side Effect: Headache

Headache is the most frequently reported side effect of nitroglycerin patches. It occurs because nitroglycerin dilates blood vessels throughout the body — including in the head — which can trigger a throbbing or pressure headache, especially when you first start therapy.

Important: do not adjust when or where you apply your patch to try to avoid headaches. Headache is often a sign the medication is working. Your doctor may recommend an over-the-counter pain reliever (like acetaminophen) for the first few weeks. Headaches typically become less severe as your body adjusts to the medication.

Other Common Side Effects of Nitro-Dur

Dizziness and lightheadedness: Particularly common when standing up quickly. This is caused by a drop in blood pressure (orthostatic hypotension). Rise slowly from sitting or lying positions, especially in the morning.

Flushing: A feeling of warmth or redness of the skin, most noticeable in the face and upper body.

Application site irritation: Redness, itching, or mild rash at the patch application site. Rotate placement sites daily to minimize skin irritation.

Low blood pressure: Nitroglycerin is a vasodilator — it lowers blood pressure as a therapeutic effect. This can become problematic if you're also on other blood-pressure-lowering medications or are dehydrated.

Serious Side Effects: When to Call Your Doctor Immediately

Severe hypotension: If you feel very faint, have blurred vision, or nearly pass out — especially after standing up — remove the patch and contact your doctor. Severe low blood pressure can be dangerous.

Syncope (fainting): If you actually lose consciousness, seek emergency medical attention.

Worsening chest pain: Rarely, nitroglycerin can worsen angina in patients with hypertrophic cardiomyopathy. If your chest pain gets worse rather than better after starting the patch, contact your cardiologist.

Signs of allergic reaction: Hives, difficulty breathing, or swelling of the face or throat indicate a serious allergic reaction. Remove the patch and call 911.

Signs of methemoglobinemia (very rare): Blue-colored lips or skin, unusual weakness, and shortness of breath. This is rare but serious — seek emergency care immediately.

Critical Drug Interaction Warning: Do Not Take Nitro-Dur With ED Medications

This is one of the most important safety warnings associated with Nitro-Dur. Taking nitroglycerin in any form with phosphodiesterase-5 (PDE-5) inhibitors — the class of medications used for erectile dysfunction and pulmonary arterial hypertension — can cause a sudden, severe, life-threatening drop in blood pressure. This combination is absolutely contraindicated.

PDE-5 inhibitors to avoid include:

Sildenafil (Viagra, Revatio)

Tadalafil (Cialis, Adcirca)

Vardenafil (Levitra, Staxyn)

Avanafil (Stendra)

How to Minimize Side Effects

Rotate patch application sites daily to reduce skin irritation

Rise slowly from sitting or lying positions to reduce dizziness

Limit or avoid alcohol while using Nitro-Dur — alcohol amplifies blood-pressure-lowering effects

Stay hydrated, especially in hot weather or during exercise

Do not use more than one patch at a time — using extra patches increases side effects without increasing benefit

Related: Nitro-Dur drug interactions: what to avoid | What is Nitro-Dur? Uses and dosage guide