Vardenafil (Levitra, Staxyn): what it is, side effects and how it differs

Status: FDA-approved prescription medicine for ED. Source: vardenafil hydrochloride tablets prescribing information (Lannett), DailyMed, checked 2026-10-17.

In short: vardenafil is one of the four PDE5 inhibitor pills approved in the US for erectile dysfunction, alongside sildenafil, tadalafil and avanafil (AUA Erectile Dysfunction guideline). It was first approved as Levitra in August 2003 and later as Staxyn, a tablet that dissolves on the tongue, in June 2010, both under Bayer applications (Drugs@FDA, NDA 021400; Drugs@FDA, NDA 200179). FDA now lists both brands as discontinued, and men who are prescribed vardenafil today usually get a generic. This page takes each answer from the current generic labels or another primary source. Evidence level: an approved drug backed by large placebo-controlled trials; comparisons with the other pills come mostly from pooled, indirect analyses, not head-to-head trials.

Figures come from the FDA prescribing information for vardenafil tablets, vardenafil orally disintegrating tablets, Viagra and Cialis. Each label reports its own studies, so the rows sit side by side but are not a head-to-head test. Doses and timing are set by the label and the prescriber, so they are left out here.

What is vardenafil?

Vardenafil is a prescription phosphodiesterase 5 (PDE5) inhibitor, and its label says it is “indicated for the treatment of erectile dysfunction” (vardenafil tablets label, section 1). It comes as a standard tablet that is swallowed and as an orally disintegrating tablet that melts on the tongue. The label lists its initial US approval as 2003 and says it is not indicated for women or for children. Vardenafil is the active ingredient; Levitra and Staxyn were brand names for it.

Is vardenafil the same as Levitra?

Yes, Levitra was the original brand name for vardenafil hydrochloride tablets, held by Bayer and approved by the FDA on August 19, 2003 as a new molecular entity (Drugs@FDA, NDA 021400). FDA now lists every Levitra strength as discontinued, with a Federal Register determination that it “was not discontinued or withdrawn for safety or effectiveness reasons.” Staxyn, the dissolving version, has the same status (Drugs@FDA, NDA 200179). Generic vardenafil labels from other makers remain listed on DailyMed, such as the Lannett tablet label and the Alembic dissolving tablet label. An approved generic is a different thing from a compounded or “research” product, which is not FDA-approved.

How does vardenafil work?

Vardenafil blocks PDE5, the enzyme that breaks down cGMP, the chemical messenger that relaxes smooth muscle in the penis so more blood can flow in during arousal. The label explains that sexual stimulation releases nitric oxide, which raises cGMP, and that “the inhibition of PDE5 has no effect in the absence of sexual stimulation” (vardenafil tablets label, section 12.1). It does not raise desire and does not cause an erection by itself. That is the same mechanism as the other pills in the class, which our explainer on how ED medications work walks through step by step.

What is the dissolving form of vardenafil?

The dissolving form is an orally disintegrating tablet, first sold as Staxyn and now available as a generic, that is placed on the tongue and “should be taken without liquid” (vardenafil ODT label, section 2.1). The label says it is “not interchangeable” with the film-coated Levitra tablet, because it gives higher blood levels than that tablet at the same strength: in healthy volunteers, peak level was 15% higher and total exposure 44% higher. Water matters too. When the dissolving tablet was swallowed with water, total exposure fell by 29%, and in the trials it was given without water. A high-fat meal lowered its peak level by 35% without changing total exposure, and the label says it can be taken with or without food.

The dissolving tablet carries a few rules of its own. The label says not to start vardenafil with it in men who take alpha-blockers, not to use it with strong or moderate CYP3A4 blockers, and not to use it with moderate or severe liver disease (vardenafil ODT label, sections 2.4, 5.2 and 5.8). It contains aspartame, a source of phenylalanine, which matters for anyone with phenylketonuria (PKU); the Lannett standard tablet carries the same phenylalanine warning (vardenafil tablets label, section 5.13). It is supplied in blister packs, and the label says to take it immediately after removing it from the blister and not to use it if a blister is torn, broken or missing. For storage and the printed date on either form, see does vardenafil expire.

What side effects does the label list?

The common side effects are the ones expected from widening blood vessels: headache, flushing, a runny or stuffy nose and indigestion. In placebo-controlled trials of the swallowed tablet, headache was reported by 15% of men on vardenafil against 4% on placebo, flushing by 11% against 1%, rhinitis by 9% against 3% and indigestion by 4% against 1% (vardenafil tablets label, section 6.1). Sinusitis, flu-like symptoms, dizziness, nausea and a raised muscle enzyme (creatine kinase) were each reported by 2% to 3%. The label notes a dose effect for headache, flushing, indigestion, nausea and rhinitis, and 3.4% of men stopped because of side effects, against 1.1% on placebo.

The dissolving tablet’s own trials showed a similar pattern: headache in 14.4% against 1.8% on placebo, flushing in 7.6% against 0.6%, and nasal congestion, indigestion, dizziness and back pain each in 2% to 3.1% (vardenafil ODT label, section 6.1). Less common effects listed on both labels include changes in color vision, sensitivity to light, eye pain, ringing in the ears and muscle aches. The label warns that side-effect rates from different drugs’ trials cannot be compared directly. Our guide to ED medication side effects covers the class as a whole.

What serious warnings does the vardenafil label carry?

The serious warnings are the same as for the rest of the class, plus the heart-rhythm caution covered in the next section. The label says to stop all PDE5 inhibitors and seek medical attention for sudden loss of vision in one or both eyes, which can be a sign of a rare optic nerve condition called NAION, and for a sudden drop in or loss of hearing (vardenafil tablets label, sections 5.4 and 5.5). It also says an erection lasting longer than 4 hours needs immediate medical help, because untreated priapism can cause lasting damage (section 5.3). On vision, the label cites observational studies suggesting roughly a 2-fold higher risk of NAION soon after PDE5 inhibitor use, while stating that neither those studies nor the reports “substantiate a causal relationship.”

Postmarketing reports listed on the label also include seizures and transient global amnesia, reported “in temporal association” with vardenafil, which means they happened around the time of use without proof that the drug caused them (vardenafil tablets label, section 6.2). NIDDK lists the same reasons to call a health care professional right away: an erection lasting longer than 4 hours, or vision or hearing loss after taking oral ED medicines (NIDDK, Treatment for ED).

Why does the vardenafil label carry a QT warning?

The label carries a QT warning because a study found vardenafil lengthens the QT interval, a measure of how long the heart’s electrical recharge takes, by about as much as the antibiotic moxifloxacin (vardenafil tablets label, section 5.7). In that study of 59 healthy men aged 45 to 60, a usual dose and a dose four times the highest recommended one both produced corrected QT increases similar to moxifloxacin’s, and a later study found the effect added up when vardenafil was combined with gatifloxacin, another drug with a similar QT effect (section 12.2). The label says “the clinical impact of these QTc changes is unknown.” It still tells men with congenital long QT syndrome, or who take Class 1A antiarrhythmics such as quinidine and procainamide or Class III antiarrhythmics such as amiodarone and sotalol, to avoid vardenafil, and asks prescribers to weigh it for anyone with a history of QT prolongation or on other QT-prolonging medicines.

What medicines interact with vardenafil?

The interaction rules fall into two groups: medicines that lower blood pressure further, and medicines that raise vardenafil levels in the blood. Vardenafil must never be taken with nitrates or nitric oxide donors, used “regularly and/or intermittently,” or with guanylate cyclase stimulators such as riociguat, and the label says a safe interval for giving nitrates after a dose “has not been determined” (vardenafil tablets label, section 4). Alpha-blockers such as tamsulosin, terazosin and alfuzosin can add to its blood-pressure-lowering effect, so the label wants men stable on them before vardenafil starts, at the lowest starting dose, and it notes vardenafil may add to other blood pressure medicines too (sections 5.6 and 7.1). Our page on nitrates and ED medications explains why that combination is the most dangerous one.

Vardenafil is cleared mainly by the liver enzyme CYP3A4, so drugs that block it raise vardenafil levels. On the label, ritonavir raised total exposure 49-fold and stretched the half-life to 26 hours, indinavir raised it 16-fold, ketoconazole 10-fold and erythromycin 4-fold, and the label says grapefruit juice would likely raise exposure too (vardenafil tablets label, section 7.2). For the standard tablet the label sets lower limits with these drugs, and for the dissolving tablet it says not to use them together at all. In the label’s study of healthy volunteers, vardenafil did not add to alcohol’s effect on blood pressure. No drug-level interactions were seen with warfarin, digoxin or glyburide, and vardenafil did not add to aspirin’s effect on bleeding time (sections 7.1 to 7.3). The label also says combining vardenafil with other ED treatments has not been studied and is not recommended (section 5.10).

How well did vardenafil work in its trials?

Vardenafil beat placebo in every main trial on its label, with smaller gains in harder-to-treat groups. In the main North American trial of 762 men, the share of attempts in which the erection lasted long enough for successful intercourse reached 51% to 65% across the doses tested at 3 months, against 32% on placebo (vardenafil tablets label, section 14.1). In 439 men with diabetes, it reached 49% to 54% against 23% on placebo, and in 427 men after radical prostate removal, 34% to 37% against 10% (sections 14.2 and 14.3). In the two trials of the dissolving tablet, where about half the men were 65 or older, the figures were 65% and 60% against 26% and 27% on placebo (vardenafil ODT label, section 14). These are trial averages across many attempts, not a forecast for one man.

How does vardenafil compare with the other ED pills?

On its label, vardenafil sits closest to sildenafil: both are short-acting, with a median time to peak of 60 minutes and a half-life of about 4 to 5 hours for vardenafil and about 4 hours for sildenafil, while tadalafil’s half-life is 17.5 hours (vardenafil tablets label; Viagra label; Cialis label). What sets vardenafil apart on paper is the dissolving tablet, the QT section in its warnings and a slightly higher lab selectivity for PDE5 over PDE6, the retina enzyme tied to color-tinged vision. In pooled trial data, a 2015 network meta-analysis (82 trials and 47,626 men for efficacy, 72 trials for side effects) found that at starting doses vardenafil had overall side-effect rates similar to sildenafil’s “but a markedly lower global efficacy” (Chen et al., European Urology, 2015). Those rankings rest on indirect comparisons and describe groups, not any one man, who may respond better to one pill than another.

For the closest pairing, see vardenafil vs sildenafil. For the two most prescribed pills side by side, see tadalafil vs sildenafil, and for the newest of the four, our explainer on avanafil (Stendra).

Who should not take vardenafil, or should be extra careful?

Some men were left out of vardenafil’s trials, so the label does not recommend it for them until more is known. That group includes men with unstable angina, low resting blood pressure (systolic below 90), uncontrolled high blood pressure (above 170/110), severe heart failure, or a stroke, heart attack or life-threatening heart rhythm problem within the last 6 months (vardenafil tablets label, section 5.1). The label says not to use it with severe liver disease or on kidney dialysis, does not recommend it with inherited retinal disease such as retinitis pigmentosa, and asks for caution with a curved or scarred penis, including Peyronie’s disease, and with conditions that raise the risk of a prolonged erection, such as sickle cell anemia, multiple myeloma or leukemia. Men 65 and older have higher blood levels of vardenafil, so the label suggests a lower starting dose for them. The label also warns that vardenafil “offers no protection against sexually transmitted diseases.”

When should you talk to a clinician about vardenafil?

Before taking it, because vardenafil is a prescription medicine and the label says ED should first be evaluated for “potential underlying causes” (vardenafil tablets label, section 5). The American Urological Association says men with ED should be told about FDA-approved oral PDE5 inhibitors, “including discussion of benefits and risks/burdens, unless contraindicated,” and should be counseled that ED “is a risk marker for underlying cardiovascular disease” (AUA Erectile Dysfunction guideline). Bring a full list of medicines, including heart rhythm drugs, antibiotics, antifungals, HIV medicines, and blood pressure and prostate medicines, and mention any heart rhythm, eye, liver or kidney history, or PKU. Which pill fits, which form, and how to take it is a decision for you and the prescriber.

Sources

1. Vardenafil hydrochloride tablets, prescribing information, Lannett Company, DailyMed (label updated July 2026)
2. Vardenafil hydrochloride orally disintegrating tablets, prescribing information, Alembic Pharmaceuticals, DailyMed
3. Drugs@FDA: NDA 021400, Levitra, US Food and Drug Administration
4. Drugs@FDA: NDA 200179, Staxyn, US Food and Drug Administration
5. Viagra (sildenafil citrate) tablets, prescribing information, Pfizer, DailyMed
6. Cialis (tadalafil) tablets, prescribing information, Eli Lilly, DailyMed
7. Chen L et al. Phosphodiesterase 5 inhibitors for the treatment of erectile dysfunction: a trade-off network meta-analysis. European Urology, 2015
8. Treatment for Erectile Dysfunction, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
9. Erectile Dysfunction: AUA Guideline, American Urological Association