Avanafil and Isosorbide Dinitrate: What to Know

Imagine you are a pharmacist and a customer asks for avanafil. Their profile shows a heart medicine you recognise instantly: isosorbide dinitrate. Everything stops. Isosorbide dinitrate is an organic nitrate, and avanafil must not be used alongside organic nitrates. The pharmacist’s job now becomes detective work: confirm what the heart medicine is, how often it is taken, whether other nitrates are in the picture, and who needs to be called.

This article is built around that detective work. Instead of a standard explainer, we treat the avanafil and isosorbide dinitrate question like a case file, with clues, red herrings and a closing checklist you can use on your own medicine cabinet. By the end, you should be able to spot a hidden nitrate, understand the reasoning behind the label warning, and know what to ask your doctor if you live with both heart disease and erectile dysfunction.

Disclaimer: this is general health information, not personal medical advice. Never change a heart medicine without the guidance of the clinician who prescribed it.

Case summary

Suspect combination: avanafil (Stendra) plus isosorbide dinitrate.
Charge: additive vasodilation that can cause a dangerous fall in blood pressure.
Verdict in the prescribing information: contraindicated; organic nitrates in any form, regular or intermittent.
Key witness: your pharmacist, who can see what your prescribers cannot.
Recommended next step: do not combine; ask your cardiologist and urologist for a joint plan.

Clue one: what isosorbide dinitrate is, and where it fits

Isosorbide dinitrate (ISDN) has been used for decades. It is a vasodilator that gets converted in the body into nitric oxide, which relaxes the muscle in blood vessel walls. By widening veins and, to a lesser extent, arteries, it reduces the amount of work the heart must do. Doctors prescribe it to prevent angina and, in some regimens, to treat heart failure.

ISDN is generally taken two or three times a day in an immediate-release form, with dosing times arranged to leave a nitrate-free stretch. It is also available as a sublingual tablet for acute angina in some markets, and as part of a fixed-dose combination with hydralazine used in heart failure care. Different brand names and formats mean a patient can take ISDN for years without ever thinking of it as “the same family” as nitroglycerin.

Clue two: why avanafil collides with it

Avanafil is a PDE5 inhibitor. It prevents the enzyme PDE5 from destroying cyclic GMP, the signalling molecule that tells smooth muscle to relax. Nitrates, including ISDN, raise cyclic GMP by delivering nitric oxide. When both drugs are on board, cyclic GMP builds up well beyond what either would achieve alone.

In the penis, that is the desired effect. In the rest of the circulation, it can produce profound vasodilation. Blood pressure may plunge, the brain and heart may be starved of blood flow, and a person with coronary artery disease is particularly vulnerable because a sudden drop in perfusion pressure can trigger the very ischaemia they take ISDN to prevent. This is why the avanafil label treats nitrates as a hard stop rather than a “monitor and adjust” issue.

Clue three: the aliases of isosorbide dinitrate

A frequent reason for near-misses is a naming mismatch. A patient says, “I do not take nitrates,” and in good faith means “I do not take nitroglycerin.” The table below lists names you may encounter.

You may see	What it is	Counts as a nitrate?
Isosorbide dinitrate, ISDN	The generic name	Yes
Isordil, Dilatrate-SR	Brand names in some markets	Yes
BiDil	Isosorbide dinitrate combined with hydralazine	Yes, it contains a nitrate
Isosorbide mononitrate, ISMN	A related long-acting nitrate	Yes
Nitroglycerin, GTN, Nitrostat, Nitrolingual	A shorter-acting nitrate	Yes
Amyl, butyl or isobutyl nitrite (“poppers”)	Inhaled recreational nitrites	Related vasodilators; avoid with PDE5 inhibitors

If any of these appear on your list, treat avanafil as off the table until a doctor has reviewed your situation. Our related guides on avanafil and nitroglycerin and avanafil and isosorbide mononitrate cover those siblings.

Clue four: the red herring of BiDil

BiDil combines isosorbide dinitrate with hydralazine and is used in specific heart-failure situations. People often remember the second drug, the hydralazine, as a “blood pressure pill,” and overlook the nitrate half of the tablet. If you are on BiDil, you are on ISDN. The pharmacist checking an avanafil request will treat the profile the same as for plain ISDN. Heart failure also adds its own reasons for caution, since labels advise that sexual activity should be avoided when it is inadvisable because of cardiovascular status.

Clue five: poppers and other nitrate-like products

Alkyl nitrites inhaled for a brief rush are not prescription nitrates, but they relax smooth muscle through a related pathway and can cause sudden drops in blood pressure. They are widely cautioned against in combination with PDE5 inhibitors. A pharmacist who asks about recreational substances is not making a moral judgement. They are building a complete picture so that nothing dangerous remains hidden. Share it candidly; confidentiality is part of their professional duty.

The pharmacist’s questioning sequence

A good interview is usually short but purposeful. Here is a typical flow, with the reason behind each question.

“What do you take for your heart?” Open-ended, so you volunteer names rather than answering yes or no.
“Do you carry anything for chest pain?” Catches rescue products.
“How often do you take the isosorbide?” Establishes whether it is a daily regimen or an occasional one. Either way, the nitrate contraindication stands.
“Who prescribed it, and when was your last review?” Helps decide whether a call to the cardiologist is needed.
“Any heart attack, stent, bypass, stroke or heart failure in the past six months?” Recent events raise the bar for any sexual activity.
“Do you use anything else, such as supplements, inhalers or recreational products?” Rounds out the list.
“Where else do you fill prescriptions?” A second pharmacy can hide a nitrate from view.

Weighing what the label says and what it does not say

It helps to read the avanafil prescribing information precisely, because online discussions often overstate or understate it.

It says that use with any form of organic nitrate, regularly or intermittently, is contraindicated.
It says that if a nitrate becomes medically necessary in a life-threatening situation after a dose of avanafil, at least 12 hours should elapse and the patient should be closely monitored.
It does not say that a nitrate-free interval in a daily nitrate regimen creates a safe window for avanafil.
It does not say that a lower avanafil dose is safe with a nitrate.

The label’s patient counselling section also tells people who experience anginal chest pain after taking avanafil to seek immediate medical attention. In other words, the document anticipates the moment when a heart patient and a PDE5 inhibitor collide and gives a clear instruction: get help.

Interpreting your own risk: three profiles

Profile A: daily ISDN user with controlled angina

You take ISDN two or three times a day and have not had chest pain for months. The label still prohibits avanafil. Your next step is a joint conversation, ideally with both your cardiologist and urologist, about whether a non-PDE5 ED option fits you.

Profile B: someone prescribed ISDN after a hospital stay

Your heart may still be recovering, and your care team may have given activity guidance. Ask whether sexual activity is appropriate now, and what warning signs should lead you to stop. ED treatment waits until that conversation is complete.

Profile C: someone who stopped ISDN a while ago

If a doctor has formally discontinued your nitrate, tell the pharmacist and your prescriber. The label focuses on current nitrate use, but your clinician will still consider your overall heart health. Do not make this call alone, and do not stop a nitrate without medical direction.

Practical alternatives when a PDE5 inhibitor is not an option

People are sometimes surprised that ED treatment is not limited to tablets. Options your urologist may discuss include:

Vacuum erection devices, which draw blood into the penis mechanically and use a constriction ring to maintain firmness.
Intracavernosal injections, typically alprostadil, which act locally and do not rely on the PDE5 pathway.
Urethral alprostadil, a small suppository placed in the urethra.
Penile implants, considered when other treatments fail or are unsuitable.
Testosterone assessment, because low levels contribute to reduced desire and erectile quality in some men.
Sex therapy or counselling, especially when anxiety about heart health has grown since a cardiac event.

Exercise is also valuable. Regular, appropriately supervised activity improves vascular function and can improve both heart symptoms and erections. Our guide to physical therapy for erectile dysfunction provides one structured approach.

Why ISDN dosing schedules confuse the avanafil question

Isosorbide dinitrate is typically prescribed at set times, often with the last dose of the day taken in the afternoon, so that the body has a drug-free period overnight. Patients who see this pattern frequently assume the evening is a protected window. Three facts undermine that assumption.

Active breakdown products linger. ISDN is converted in the body to compounds that remain active for longer than the parent drug, so the effect on blood vessels outlasts the time at which you took the tablet.
People differ. Liver function, age, kidney health, other medicines and even hydration alter how long vasodilating drugs act.
Schedules change. A cardiologist may adjust the dose or timing after a symptom flare, and you may not recalculate your own plan accordingly.

The label does not offer a calculation that turns these variables into a safe interval, and a blog article cannot responsibly invent one. What a clinician can do is decide whether you should remain on a nitrate at all.

The heart-failure angle

ISDN is not only an angina drug. In heart failure, a nitrate can relieve congestion by widening veins, and in certain populations it is combined with hydralazine. Heart failure introduces additional questions for anyone considering avanafil:

Is the heart failure stable, or have you had recent hospital admissions?
Does physical exertion cause breathlessness or chest discomfort?
Are you taking diuretics, which can reduce blood volume and make low blood pressure more likely?
Are you on newer heart-failure drugs, including vericiguat, which is contraindicated with PDE5 inhibitors?

The avanafil label advises that patients should not use it if sexual activity is inadvisable because of cardiovascular status. For heart-failure patients, that determination belongs to the treating cardiologist. A pharmacist will usually encourage you to ask, because the answer shapes everything else.

Age, kidneys, liver and hydration

Several body conditions modify the risk of low blood pressure even without a nitrate present. A pharmacist reviewing your file will think about them as background factors:

Older age. Blood-pressure regulation tends to be less flexible with age, so standing up quickly can cause dizziness.
Liver disease. Avanafil is not recommended in severe hepatic impairment, because the liver handles most of its breakdown.
Kidney disease. Dosing guidance for some patients with reduced kidney function is more cautious.
Dehydration. Fever, vomiting, diarrhoea or heavy sweating shrink blood volume, which makes any vasodilator more potent.
Alcohol. The label treats substantial alcohol intake as another contributor to low blood pressure.

These factors do not replace the nitrate rule; they add to it. When a pharmacist asks about your hydration, drinking habits and recent illnesses, they are building a realistic picture of your circulation.

Myths people repeat in forums

“ISDN is weaker than nitroglycerin, so it is safe.” Potency is not the point. The contraindication covers organic nitrates as a group.
“I only take it twice a week.” Intermittent use is explicitly included in the warning.
“My doctor never mentioned it, so it must be fine.” Prescribers see only their own part of the story. Ask directly.
“Younger men do not have to worry.” Nitrates are prescribed for medical reasons, not age. A younger person with a nitrate prescription still faces the contraindication.
“Everyone online takes both.” Anecdotes from people who did not come to harm do not describe the risk for the person who does.

How to talk to both of your prescribers

People with ED and heart disease often have two or more specialists, and each assumes the other has the full picture. You can bridge the gap with a short, factual message that you bring to each appointment or send through a patient portal.

A template for your cardiologist

“I take isosorbide dinitrate for my heart. I am having erectile dysfunction and would like to know whether my nitrate is still required, whether my heart is stable enough for sexual activity, and which ED treatments you would consider compatible with my current plan.”

A template for your urologist or primary care doctor

“I am on isosorbide dinitrate, which I understand is contraindicated with PDE5 inhibitors. I would like to discuss ED treatments that do not rely on that pathway. Here is my full medicine list.”

What to bring

Your up-to-date medicine list with doses and times
Names of everyone who prescribes for you
Recent blood-pressure readings, if you track them at home
A note of any symptoms during exertion or intimacy, such as chest tightness or breathlessness
Your questions, written down

When the conversation reveals something else

Sometimes a pharmacist’s questions uncover a different issue. A customer mentions that chest pressure occurs during sexual activity, or that dizziness has become frequent. Those symptoms are worth taking seriously on their own, regardless of any ED prescription. A prompt medical review can detect worsening coronary disease, rhythm problems or medication side effects before they become emergencies. Likewise, if the ED itself began recently, a clinician may check blood sugar, blood pressure, cholesterol and hormones, because ED can be the first visible sign of a wider vascular or metabolic problem. Our guide to sexual activity as men age offers perspective on what is typical and when a symptom deserves attention.

Self-audit worksheet: does anything in my cabinet count as a nitrate?

Take ten minutes with your medicines and answer each item below. If any answer is “yes,” speak to your pharmacist before taking avanafil.

Do I have a bottle containing isosorbide dinitrate, isosorbide mononitrate or nitroglycerin?
Do I have a spray, patch or ointment from a doctor that I have not used recently?
Have I ever been given a medicine called BiDil, Isordil or Dilatrate?
Has a surgeon prescribed an ointment for anal fissures?
Do I use inhaled “poppers” or similar products?
Do I take a lung or heart medicine named riociguat or vericiguat? (These are separate contraindications; see avanafil and riociguat.)
Do I take a prostate medicine such as tamsulosin or doxazosin? (This calls for dosing care; see avanafil and tamsulosin.)

Reading between the lines of ED marketing

Telehealth ads and online pharmacies frequently promote avanafil as quick-acting and well tolerated. Those statements may be accurate for the patients studied, but a generic benefit claim cannot account for your personal medicine list. Before ordering, look for a clear screening step that asks about heart conditions and nitrates. If a website offers to ship without asking, consider that a warning about the seller. Our explanation of how to spot fake Kamagra oral jelly shows the kinds of red flags that appear with unregulated products.

Also be careful when comparing drugs. Pages such as Stendra versus Cialis or Stendra versus Levitra help you understand differences in onset, duration and side effects, but every PDE5 inhibitor comes with the same nitrate caution.

If the worst happens: an action plan

Suppose you realise you took avanafil and ISDN together. The following steps can make a real difference:

Stop and sit. Lying down with the legs raised can ease the effects of a sudden drop in pressure.
Do not stand quickly. Rising fast can cause fainting.
Call emergency services if you feel faint, have chest pain, palpitations, breathlessness or confusion.
Give exact details: drug names, doses and times.
Bring the packages to the hospital.
Follow up with your pharmacist and prescribers so the record is corrected.

If you feel entirely well, you still deserve a call to a pharmacist or poison-control service. Symptoms can be delayed, and an expert can tell you what to watch for and for how long.

Frequently asked questions

Is isosorbide dinitrate the same as isosorbide mononitrate?

They are related but not identical. Both are nitrates, both are included in the contraindication, and both can lower blood pressure.

If I take ISDN only when I have chest pain, can I use avanafil on other days?

The label covers intermittent use. Because angina can occur unpredictably, the rescue medicine would still be needed in an emergency. Discuss this with your cardiologist rather than trying to schedule around it.

Is Stendra the only ED drug with this warning?

No. Sildenafil, tadalafil, vardenafil and avanafil all share the nitrate contraindication. If you are comparing them in general, see our guides on avanafil versus Viagra and avanafil versus tadalafil.

Could my doctor prescribe both with monitoring?

The label reserves nitrate use after avanafil for life-threatening emergencies under close monitoring. It does not describe a routine arrangement for combining them.

Do natural supplements help me avoid the issue?

Not automatically. Some natural products also lower blood pressure or contain undeclared drugs. Read our piece on natural alternatives to Stendra and share every product you use with your pharmacist.

Does ED mean my heart is in trouble?

Not always, but ED and cardiovascular disease share risk factors, and ED can be an early sign. If you have not yet had a heart check, mention the symptom to a doctor.

The bottom line for isosorbide dinitrate users

If you take isosorbide dinitrate in any form, the answer to “can I add avanafil?” is a firm no unless a physician has changed your heart regimen first. That is not a judgement about your lifestyle or your relationship; it is a protective rule built around how two drug classes act on the same blood-vessel pathway. The constructive response is to bring the question to the right people, ask for a coordinated plan, and explore the many ED options that do not depend on a PDE5 inhibitor. Most people who go through that process find a workable path, and many discover that treating the underlying heart and vascular health improves their symptoms overall.

Keep exploring

For a broader view of treatment options, visit our guides on the safest drug for erectile dysfunction and blood thinners and erectile dysfunction, or browse the full PinkViva blog.

Sources

This article is educational and does not replace professional medical advice. Check current labelling and consult a licensed pharmacist or physician about your own medicines.