7 Vardenafil Interactions and How to Manage Them

Many people contend with erectile dysfunction (ED), which affects both physical and mental health. It causes trouble with achieving or maintaining an erection when you want one or feel aroused. But no matter what’s causing your symptoms, medications are one tool to consider for ED treatment.

One ED medication that you might consider taking is vardenafil. Vardenafil belongs to a class of medications known as phosphodiesterase 5 (PDE5) inhibitors. It works by increasing blood flow to the penis, and it may start working slightly faster than sildenafil (Viagra).

Vardenafil is a safe and effective medication for most people. But it may interact with other medications you might be taking. Here’s what you should know about seven notable vardenafil interactions.

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1. Nitrates like nitroglycerin

Nitroglycerin (Nitrostat, NitroMist, Nitro-Dur) and other nitrate medications are contraindicated with vardenafil. This means that they should not be taken together, either regularly or sporadically. Other nitrate medications include:

• Isosorbide dinitrate (Isordil, Isordil Titradose)

• Isosorbide mononitrate (Monoket)

• Isosorbide dinitrate and hydralazine (BiDil)

Nitrate medications lower blood pressure by opening up your blood vessels. Vardenafil has a similar effect on blood vessels when you take it. When you take these medications together, your blood pressure can drop to dangerous levels. This can result in dizziness, fainting, and more serious heart complications.

2. Alpha blockers like tamsulosin

Tamsulosin (Flomax), doxazosin (Cardura), and prazosin (Minipress) are all common alpha blocker medications. They’re used to treat an enlarged prostate and, occasionally, high blood pressure. But your blood pressure may drop too low if you take them with vardenafil. The combination can result in excessive dizziness and fainting. 

You don’t need to avoid this combination altogether. But your healthcare provider will want to make sure that your body is used to your alpha blocker dosage and tolerates it well. They’ll also likely recommend taking the lowest effective dose of vardenafil. You may be prescribed a starting dose of vardenafil 2.5 mg or 5 mg.

Try to look after your body, too, if you need to take them at the same time. It’s important to pay particular attention when you go from a lying down to a standing position. This movement can make you feel extra dizzy (orthostatic hypotension). Getting up slowly and carefully can help prevent accidental falls.

3. Blood pressure medications

There are dozens of different blood pressure medications available. Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and calcium channel blockers (CCBs) are just a few.

Vardenafil may have an additive effect with your blood pressure medications. Similar to the previous interactions, vardenafil can prompt your blood pressure to drop too low. Vardenafil’s maximum blood pressure-lowering effects tend to happen within 1 to 4 hours after a dose. You may experience dizziness, fainting, or other similar side effects if your blood pressure drops too low.

This interaction could be missed if you see two different healthcare providers for blood pressure and ED (or use different pharmacies). Consider seeing the same prescriber for both conditions or let them know you’re taking both medications. This information allows them to make adjustments to help prevent unwanted side effects.

4. Medications that contain ritonavir, including Paxlovid

Medications that contain ritonavir (Norvir) — including Paxlovid (nirmatrelvir / ritonavir) — can affect vardenafil levels in your blood. Several HIV medications, such as Kaletra (lopinavir / ritonavir), also contain it.

Medications containing ritonavir can block the action of liver enzymes (proteins) that are responsible for breaking down vardenafil. This may increase vardenafil levels in your blood, raising the risk of side effects. Headaches and flushing are two common complaints.

You shouldn’t take more than 2.5 mg of vardenafil in a 3-day period if you’re taking ritonavir.

Good to know: Headaches and flushing aren’t the only side effects of vardenafil. Vardenafil side effects are discussed in depth in another GoodRx Health article.

5. Several antifungals and antibiotics

Ketoconazole (Nizoral) is an antifungal medication that treats serious fungal infections. But it can also interfere with certain liver enzymes.

If you need to take a course of oral ketoconazole, vardenafil levels can go up. This can cause new or worsening vardenafil side effects. The topical versions of ketoconazole are less of an issue because they’re not absorbed into your body. 

If you need to combine vardenafil and ketoconazole, your healthcare provider will likely recommend a lower dose of vardenafil. The same goes for other antifungal medications that can impact vardenafil levels. These include itraconazole (Sporanox), voriconazole (Vfend), and others.

Some antibiotics can affect your vardenafil dose, too. Erythromycin (Ery-Tab) and clarithromycin (Biaxin XL) are oral antibiotics that block similar liver enzymes. Your provider will likely recommend a lower vardenafil dose if you need one of these antibiotics.

6. Medications that contain cobicistat

Cobicistat (Tybost) is a medication that’s commonly taken with other HIV medications. You can take it as a stand-alone tablet or in combination with other medications in a single pill.

Examples of cobicistat-containing medications include:

• Stribild (elvitegravir / cobicistat / emtricitabine / tenofovir disoproxil fumarate)

• Genvoya (elvitegravir / cobicistat / emtricitabine / tenofovir alafenamide) 

• Symtuza (darunavir / cobicistat / emtricitabine / tenofovir alafenamide)

• Evotaz (atazanavir / cobicistat)

• Prezcobix (darunavir / cobicistat)

Think of cobicistat as a booster medication, or a sidekick. It’s taken with other HIV medications to make them more effective. But it’s not very selective, meaning cobicistat can also boost the levels of other medications — including vardenafil. This makes side effects more likely to happen.

If you need to combine vardenafil with a medication that contains cobicistat, keep an eye out for new or worsening side effects. Make sure to report them to your provider, too. They may want to adjust your vardenafil dose.

7. Grapefruit products

Grapefruit products, including grapefruit juice, can also affect liver enzymes that break down vardenafil. Consuming large quantities of grapefruit juice makes it harder for these enzymes to do their job.

Let your healthcare provider know if you enjoy drinking grapefruit juice in frequent or large quantities. They can adjust your vardenafil dose accordingly. Alternatively, you can consider a different kind of fruit juice that doesn’t interact — such as orange or apple juice.

When should you contact your healthcare provider about a vardenafil interaction?

Don’t hesitate to contact your pharmacist if you’re ever concerned about a vardenafil interaction. They’re a great resource to manage and prevent interactions. It also helps when your pharmacist has access to an up-to-date medication list before you fill the medication at the pharmacy. It’s easier — and safer — when they’re able to screen for interactions in advance.

Keep track of how you’re feeling, too. Contact your healthcare provider if you’re experiencing side effects such as headache or flushing. These may be signs that you’re taking a vardenafil dose that is too high. They may opt to lower your dose. 

Some scenarios warrant immediate medical care. Call 911 or go to the nearest ER if you have an erection lasting more than 4 hours or experience sudden vision loss in one or both eyes.

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Written by:

Mandeep Sohal, PharmD

Mandeep Sohal, PharmD, has more than 7 years of experience in the pharmaceutical industry and is licensed in California. In his career, he’s had experience with specialty pharmacy, community pharmacy, pharmacy benefit management, and pharmaceutical manufacturers.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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