Vardenafil and Riociguat: What Should Your Pharmacist Check?

Most people who ask about vardenafil and riociguat are in a very specific situation. They, or someone they care for, live with pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH). They take riociguat (brand name Adempas) to ease the pressure in the lung arteries. And, like many men with a chronic condition, they are also struggling with erections and wondering whether vardenafil (Levitra, Staxyn or a generic) is an option.

The answer is clear: vardenafil and riociguat must not be taken together. Both medicines boost the same chemical signal in blood vessels, and combining them can cause a dangerous drop in blood pressure. But the story is more nuanced than a single “no,” because many PAH patients have taken PDE5 inhibitors in the past, some are switched from one drug to the other, and ED treatment is still possible. This article explains what your pharmacist checks, why, and what to talk about with your pulmonary hypertension team.

At a Glance

Interaction status: Contraindicated in both the vardenafil and riociguat product information.
Why: Additive effect on the nitric oxide → soluble guanylate cyclase → cGMP pathway, causing low blood pressure.
Applies to: All PDE5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil) and non-specific PDE inhibitors such as dipyridamole and theophylline.
Key timing rule from labelling: Riociguat should be stopped at least 24 hours before a PDE5 inhibitor is given; specific gaps after stopping a PDE5 inhibitor exist for sildenafil and tadalafil, but data for vardenafil are limited.
Who decides: Your specialist pulmonary hypertension centre, not a general ED prescription.

One Pathway, Two Pushes: The Science Made Simple

Picture a three-step relay inside the smooth muscle of every blood vessel.

Nitric oxide (NO) is released by the vessel lining.
NO switches on an enzyme called soluble guanylate cyclase (sGC), which manufactures cGMP.
cGMP tells the muscle to relax, so the vessel widens. An enzyme called PDE5 then mops up cGMP to end the signal.

Riociguat pushes on step 2. It stimulates sGC directly, and also makes it more sensitive to whatever NO is around, so more cGMP is made. This helps relax the narrowed lung arteries in PAH and CTEPH.

Vardenafil pushes on step 3. It blocks PDE5, so cGMP isn’t cleared as quickly. In the penis, that sustains an erection. But PDE5 also exists in other vessels, including the lungs and the rest of the body.

Put both together and cGMP is being made faster and cleared slower. The result is far more vessel relaxation than intended, everywhere, and blood pressure can fall sharply. European regulators reviewing safety data noted that both drug types act on the NO–sGC–cGMP pathway and may produce synergistic, body-wide vasodilation (EMA scientific conclusions on tadalafil and riociguat). That review also referred to a study extension in which deaths occurred during combined riociguat and sildenafil treatment, one of which was assessed as possibly related to the combination.

Who Takes Riociguat, and Why ED Comes Up

Riociguat is a specialist drug. It is licensed for:

CTEPH that cannot be operated on, or that persists or recurs after surgery to remove clots from the lung arteries.
PAH, often alongside an endothelin receptor antagonist such as ambrisentan, bosentan or macitentan.

Erectile dysfunction is common in men with pulmonary hypertension. Breathlessness, fatigue, low oxygen levels, low mood, other medicines and the sheer strain of a serious diagnosis all play a part. Because sildenafil and tadalafil are also used to treat PAH (sold as Revatio and Adcirca at PAH doses), many patients and even some prescribers assume an ED dose of vardenafil would be harmless. That assumption is exactly what makes this interaction dangerous. For background on why sildenafil carries two brand names, see Revatio vs Viagra.

The Switching Question: Moving Between PDE5 Inhibitors and Riociguat

Here is where the topic gets more practical. PH specialists sometimes switch a patient from a PDE5 inhibitor to riociguat when PAH is not responding well enough. Because the two drug types cannot overlap, the switch needs a careful gap. Riociguat interaction summaries and product information give these reference points:

Situation	What labelling and interaction references say
Starting a PDE5 inhibitor after riociguat	Stop riociguat at least 24 hours before the PDE5 inhibitor
Starting riociguat after sildenafil	Do not give riociguat within 24 hours of the last sildenafil dose
Starting riociguat after tadalafil	Do not give riociguat within 48 hours of the last tadalafil dose
Starting riociguat after vardenafil or avanafil	Limited data; the specialist team decides the interval

These intervals come from riociguat interaction guidance summarised by sources including MecDDI’s vardenafil–riociguat entry. They exist for switching under specialist supervision, not for alternating the two drugs so that you can use vardenafil “on a weekend off riociguat.” Stopping riociguat without your team’s agreement can let pulmonary pressures rise and worsen symptoms.

Your Pharmacist’s Traffic-Light Check

A useful way to understand what happens at the pharmacy is to think in three colours.

Red: stop and contact the prescriber

Riociguat and vardenafil on the same profile. The pharmacist should not supply both for concurrent use and will contact the prescriber.
Riociguat plus any nitrate. Riociguat is also contraindicated with nitrates and nitric oxide donors in any form, including glyceryl trinitrate sprays and isosorbide tablets. Poppers belong here too.
Riociguat plus another sGC stimulator. Vericiguat (Verquvo), used in heart failure, works on the same enzyme. It should not be combined with riociguat.
Riociguat plus dipyridamole or theophylline. These non-specific PDE inhibitors also feature in riociguat’s contraindications.

Amber: check carefully and counsel

Strong CYP and P-gp/BCRP inhibitors such as ketoconazole, itraconazole or ritonavir increase riociguat exposure, which raises hypotension risk. A lower riociguat starting dose and monitoring may be advised (review of riociguat drug interactions, PMC).
Antacids containing aluminium or magnesium hydroxide reduce riociguat absorption and should be separated by at least an hour.
Smoking status. Riociguat levels are noticeably lower in smokers. Quitting can raise levels, so the PH team may need to review the dose. Stopping smoking also helps erections.
Other blood pressure–lowering drugs, including alpha-blockers for the prostate, diuretics and antihypertensives.

Green: what can usually be supported

Vacuum erection devices. Mechanical, no drug interaction.
Psychological support and sex therapy. Particularly helpful where anxiety, breathlessness during sex or depression play a role.
Exercise within PH rehabilitation programmes. Improves stamina and confidence.
Medication review for other drugs that may worsen ED, such as certain beta-blockers or antidepressants. See our guide to blood pressure medicines that can cause ED.

What If You Have Been Given Both?

Mistakes happen most often at the boundaries of care: a GP or online clinic prescribing vardenafil without seeing the specialist letter, or a hospital admission where home medicines are recorded incompletely. If you notice that both drugs are in your possession:

Do not take vardenafil.
Continue riociguat as prescribed unless your PH team tells you otherwise.
Phone your PH centre’s nurse line or your pharmacist and explain.
Ask the ED prescriber to update their records with the riociguat prescription.

If you have already taken vardenafil while on riociguat, watch closely for dizziness, light-headedness, fainting, severe headache, chest pain or worsening breathlessness. Lie down with your legs raised, and seek urgent medical help if symptoms appear, telling staff about both drugs and the timing. Even if you feel fine, call your PH team for advice, since the effects may build over several hours.

Why “PAH Doses” and “ED Doses” Don’t Change the Rule

A common source of confusion: if sildenafil is used every day for PAH at 20 mg three times a day, surely a single 10 mg vardenafil tablet is minor? The problem isn’t the size of the dose; it is the mechanism. Riociguat is contraindicated with PDE5 inhibitors at any dose because the combination amplifies the same pathway. PAH regimens either use a PDE5 inhibitor or riociguat as the cGMP-pathway drug, never both.

The same logic applies to tadalafil, avanafil and sildenafil. If you have read our guide on avanafil and riociguat, the principles are identical.

ED Treatment Options to Discuss With Your PH Team

Ask whether your PAH could be managed with a PDE5 inhibitor instead

This is the question many patients don’t think to ask. For some people, a PDE5 inhibitor such as sildenafil or tadalafil may be a reasonable choice for PAH, and these drugs can also help erections. Whether a switch makes sense depends on your disease type (CTEPH has fewer drug options), how well you are responding now, and your specialist’s assessment. It is not a decision to make for ED alone, but it is a fair question to raise.

Ask about local and mechanical treatments

Vacuum erection devices are often the first non-drug option. Alprostadil (injected into the penis or used as a urethral pellet) acts locally, but your team should check it is appropriate for you, since it can still have some systemic effects.

Ask about factors that make ED worse

Oxygen levels during exertion. If you desaturate during sex, supplemental oxygen or pacing may help.
Low mood. Depression is common in PH and can affect sexual function directly.
Hormones. Low testosterone can contribute; your doctor may test it.
Other medicines. Diuretics, beta-blockers and some antidepressants can dampen sexual function.

Ask whether sexual activity is safe for you

PH varies widely in severity. Some people are active and well controlled; others become breathless with minimal effort. Your team can advise on exertion limits, positions that reduce effort, and warning symptoms to stop for.

PAH vs CTEPH: Why Your Diagnosis Shapes the ED Conversation

Riociguat is used in two related but different conditions, and the difference matters when you ask about ED.

If you have PAH

Pulmonary arterial hypertension has several drug families: PDE5 inhibitors, sGC stimulators (riociguat), endothelin receptor antagonists, prostacyclin-pathway drugs and, more recently, activin-signalling inhibitors. Because a PDE5 inhibitor is one recognised option for the cGMP pathway, a PAH specialist has some room to consider which cGMP-pathway drug suits you best. That opens the door to a genuine discussion about whether a PDE5-based regimen could serve both your lungs and your erections. It may or may not be the right choice, but it’s a valid question.

If you have CTEPH

Chronic thromboembolic pulmonary hypertension is caused by old clots scarring the lung arteries. The first-line approach is often surgery (pulmonary endarterectomy) or a catheter procedure called balloon pulmonary angioplasty. Riociguat is the medicine licensed for inoperable or persistent CTEPH, and there are fewer alternatives. That means switching away from riociguat just to allow an ED tablet is less likely to be appropriate. ED care in CTEPH usually focuses on non-PDE5 routes.

Either way, the team needs to know

Telling your PH team about ED is not a distraction from “real” medical care. Sexual health affects quality of life, mood and relationships, and specialist centres are used to these conversations. If you find it difficult to raise in clinic, ask the specialist nurse, who is often the easiest first contact.

Intimacy With Pulmonary Hypertension: Practical Tips

While the drug question is being sorted out, a few practical adjustments can make sex more comfortable and less tiring:

Timing: choose times of day when you have the most energy, often after rest rather than after a meal.
Positions: positions that need less upper-body effort or lying flat on your back can reduce breathlessness. Being propped up may help.
Pacing: slow down, take breaks, and focus on touch and closeness rather than performance.
Oxygen: if you use oxygen on exertion, ask your team whether to use it during sex.
Temperature: avoid hot baths or showers right before, as heat widens blood vessels and can lower blood pressure.
Know when to stop: chest pain, fainting feelings, severe breathlessness or palpitations are signals to stop and rest, and to tell your team.

Some men also find that anxiety about breathlessness feeds into erection problems. Counselling or sex therapy can help break that cycle; our guide to psychological erectile dysfunction covers practical first steps.

Common Scenarios Pharmacists See

“My GP prescribed vardenafil; my specialist prescribes riociguat.”

This is the classic gap. The pharmacist should contact the GP, explain the contraindication, and suggest the GP liaise with the PH centre.

“I was on sildenafil for PAH, then switched to riociguat, and I still have leftover ED tablets.”

Leftover PDE5 tablets of any type should not be used while on riociguat. Return them to a pharmacy for safe disposal.

“I bought ‘herbal’ ED capsules online.”

Many such products have been found to contain undeclared PDE5 inhibitors. With riociguat, that is a hidden version of exactly the interaction you are trying to avoid. Our article on spotting fake ED products lists warning signs.

“My heart failure doctor started vericiguat. Can I use vardenafil?”

Vericiguat is a different sGC stimulator. Its labelling advises against combining it with PDE5 inhibitors for similar reasons. Ask your cardiologist and pharmacist before using any ED drug.

Spotting Low Blood Pressure Early

Whether from an interaction, dehydration or a riociguat dose increase, low blood pressure tends to announce itself. Know these signs:

Dizziness when standing up quickly
A feeling of faintness or “greying out”
Blurred vision
Unusual tiredness or weakness
Nausea
Rapid heartbeat
Cold, clammy skin

Riociguat itself can cause low blood pressure, especially when the dose is being increased. Your PH team usually checks blood pressure at each dose step. Keeping a home blood pressure log, if your team recommends it, can help them see patterns.

What to Tell an Emergency Department

People with pulmonary hypertension are sometimes seen in emergency departments by doctors who don’t manage PH day to day. A few clear sentences can prevent a medication error:

“I have pulmonary arterial hypertension (or CTEPH), treated at [name of PH centre].”
“I take riociguat [dose] three times a day.”
“I cannot have nitrates or PDE5 inhibitors such as sildenafil, tadalafil or vardenafil.”
If relevant: “I took vardenafil by mistake at [time].”

Ask staff to contact your PH centre if any change to your PH medicines is being considered. Most specialist centres provide a patient alert card for exactly this purpose; if you don’t have one, ask for it at your next visit.

Questions to Write Down Before Your Next PH Clinic

Is riociguat definitely the best cGMP-pathway drug for me, or could a PDE5 inhibitor be used instead?
If I wanted to try ED treatment, what options are safe with my current regimen?
Is sexual activity safe for me at my current exercise tolerance?
Should I use oxygen during sex?
Are any of my current medicines making ED worse?
Who should my GP or online doctor contact if they want to prescribe something for ED?

Practical Tips for Day-to-Day Safety

Keep one pharmacy. A single pharmacy record is the strongest safety net against hidden combinations.
Carry a medicine list that names riociguat and states “no nitrates, no PDE5 inhibitors.”
Tell every prescriber about riociguat, including dentists and urgent care clinics.
Avoid alcohol excess, which can add to blood pressure lowering.
Stay hydrated, especially in hot weather or if you are unwell with vomiting or diarrhoea.

Frequently Asked Questions

Can I take vardenafil if I skip my riociguat for a day?

No. Riociguat should not be stopped without your PH team’s guidance, and the labelled gap of at least 24 hours applies to supervised switching, not occasional use. Riociguat is usually taken three times daily, so skipping doses also risks worsening your pulmonary hypertension.

Is tadalafil safer than vardenafil with riociguat?

No. All PDE5 inhibitors are contraindicated with riociguat. Tadalafil actually lasts longer, so it needs a longer gap when switching.

Why can people with PAH take sildenafil but not with riociguat?

Sildenafil and riociguat are alternative ways to boost cGMP. Using one is a treatment; using both doubles up on the same pathway and risks dangerous hypotension.

What about vardenafil orally dissolving tablets?

They are still vardenafil and carry the same contraindication. See our comparison of Levitra vs Staxyn for how the forms differ.

Can women taking riociguat use vardenafil?

Vardenafil is not licensed for women, and the interaction risk would be the same. Riociguat also carries pregnancy restrictions, so women of childbearing potential on riociguat follow specific programmes with their specialist.

Does riociguat itself cause erectile problems?

ED is not listed as a common side effect of riociguat. ED in PH patients usually has several overlapping causes. A full review with your team is the best way to find out what’s driving it in your case.

Are there ED treatments my pharmacist can recommend without a prescription?

In some countries, sildenafil is available from pharmacies without a prescription after a consultation. With riociguat, a pharmacist would not supply it. Vacuum devices are generally available and are interaction-free, but discuss them with your team first.

The Takeaway

Vardenafil and riociguat work on the same blood vessel pathway from two directions. Together, they can lower blood pressure to dangerous levels, which is why both products list the pairing as contraindicated. If you take riociguat for PAH or CTEPH and want help with erections, your pharmacist’s job is to stop the combination, check for other hidden risks like nitrates and enzyme-blocking drugs, and point you back to your PH team. Your team’s job is to look at the whole picture: whether a different PAH regimen could also help ED, which non-drug options suit you, and how to keep sex both safe and satisfying.

Related Guides on Pinkviva

References

Disclaimer: This content is for educational purposes and does not replace advice from your pulmonary hypertension specialist, doctor or pharmacist. Never stop or switch riociguat or any PAH medicine without your specialist team. Seek urgent care for fainting, chest pain or severe breathlessness.