Sildenafil (Viagra) vs. Vardenafil (Levitra): Similarities, Differences, Interactions, and Side Effects

Sildenafil (Viagra) and Vardenafil (Levitra) are PDE-5 inhibitor drugs notably used to treat erectile dysfunction (ED). Individuals with ED may have problems producing or maintaining erections as firm and as long as they wish to enjoy satisfying sexual activity.

PDE-5 inhibitors are safe, effective, and commonly used ED medicines. They work under the same premise of enhancing blood flow to the penis to help improve erectile function. PDE-5 inhibitors include tadalafil (Cialis) and vardenafil (Stendra). 

However, it must be noted that all PDE-5 inhibitor drugs require sexual stimulation and arousal for them to work at their best.

 

Sildenafil (Viagra): a quick rundown

Sildenafil, also known under its brand name Viagra, is an FDA-approved oral medication for erectile dysfunction. It’s also used to treat pulmonary arterial hypertension under the brand name Revatio. Sildenafil is sometimes prescribed “off-label” to treat Raynaud’s phenomenon, altitude sickness, and female sexual arousal disorder.

 

Vardenafil (Levitra): what you should know

Vardenafil, also known under its brand name Levitra, is another DDA-approved ED drug. vardenafil may also be used as an off-label treatment for Raynaud’s phenomenon and pulmonary arterial hypertension.

 

 

Sildenafil and Vardenafil: how effective are they?

Sildenafil and vardenafil are known for their safety and effectiveness in treating ED. According to clinical studies, three out of four individuals taking standard sildenafil or vardenafil doses experienced improved erectile function. There is no known difference in effectiveness between sildenafil and vardenafil as yet.

 

How much time do Sildenafil (Viagra) and Vardenafil (Levitra) take before kicking in?

Sildenafil and vardenafil take about the same amount of time before kicking in.

 

Sildenafil

Sildenafil can kick in within 30 minutes of taking it, but can also take upwards of two hours. Sildenafil generally starts working within an hour of taking it for most individuals. This is why you should take sildenafil at least 60 minutes before you engage in sexual activity. It’s possible to take sildenafil with or without food. However, if you eat a heavy, high-fat meal, it may delay the time it takes for sildenafil to kick in.

 

Vardenafil

Vardenafil works within approximately an hour, but it can kick in as soon as 30 minutes after taking it. Similar to sildenafil, vardenafil can be taken with or without food, and can take longer to kick in if you take it after a heavy meal high in fat. 

 

How long does Sildenafil and Vardenafil last in the body?

Sildenafil (Viagra) and vardenafil (Levitra) stay in the body for about the same amount of time.

 

Sildenafil

Sildenafil’s effects generally last for up to four hours. However, this might differ based on other factors such as dosage, other health conditions you have, or if you’re taking certain types of medicines and supplements..

 

Vardenafil

Vardenafil’s effects last around four to five hours, or just slightly above that of sildenafil. Similar to sildenafil, this window of effectiveness may depend on certain factors like dosage strengths and medical history.

 

What doses are Sildenafil and Vardenafil available in? 

This is one of the key factors where sildenafil and vardenafil are clearly different.

 

Sildenafil

Sildenafil citrate, or its brand name Viagra, comes in three dosages: 25 mg, 50 mg, or 100 mg oral tablets.

In general, most individuals with ED are given the starting dose of 50 mg, to be taken 30 minutes to an hour before engaging in sex. Depending on your medical history, however, your doctor may decide to switch you on a lower or higher dose.

You can take sildenafil on an empty stomach or with food. Taking a heavy, high-fat meal may take your body longer to absorb the drug, taking it longer to kick in.

The maximum single daily dose for sildenafil is 100 mg per day.

 

Vardenafil

Vardenafil hydrochloride, also sold as Levitra, is an oral tablet available in 2.5 mg, 5 mg, 10 mg, and 20 mg doses.

Most people with ED who are prescribed vardenafil are put on a starting dose of 10 mg. Your starting dose may be adjusted by your doctor depending on your medical history.

Vardenafil should be taken approximately one hour before engaging in sexual activity. You can take vardenafil with or without food, but a heavy meal may delay the time it takes to kick in.

The maximum single daily dose for vardenafil is 20 mg per day. 

 

What side effects should I expect from taking Sildenafil and Vardenafil?

Sildenafil and vardenafil’s side effects are similar and your mileage may vary depending on your dose, medical history, and other considerations.

 

• Low blood pressure (hypotension). ED drugs, which belong to the PDE-5 inhibitor category of drugs, work by relaxing the penis’ blood vessels to enable greater blood flow into it. In doing so, they help produce and maintain erections longer. However, their effects aren’t just limited to penile blood flow––they affect the entire circulatory system. The relaxation of blood vessels may cause blood pressure to drop precipitously. In some cases, this effect is desirable in a drug. But for people with low blood pressure or people taking medicine to reduce their blood pressure, the risks of developing extremely low blood pressure can be fatal.
• Priapism. Priapism is a painful and serious medical condition when an erection lasts for more than four hours. If priapism isn’t relieved immediately, it can cause irreversible damage to penile tissue. All PDE-5 inhibitor drugs, including sildenafil and vardenafil, increase your risk of experiencing priapism. They might be responsible in one out of four cases of priapism.

 

What are the side effects of sildenafil?

Here are the most common side effects of Sildenafil as follows:

 

• Facial redness/flushing
• Headaches/dizziness
• Heartburn
• Indigestion
• Lower back pain
• Nasal congestion
• Nausea or weakness

 

About 3% of individuals in clinical studies experienced changes in vision after taking sildenafil (Viagra). This effect was temporary and reported as causing a blue tinge to their vision perception. Fortunately, this side effect is rare and temporary.

Sildenafil may also increase individuals’ risk of developing non-arteritic ischemic optic neuropathy (NAION) in people who are predisposed with other risk factors for this condition. NAION may cause changes in vision that may be temporary or permanent. 

Individuals with risk factors for cardiovascular disease such as hypertension, high cholesterol, or diabetes, or a history of strokes or heart attacks may experience chest pain or heart attacks. That said, if you have a medical history of cardiovascular disease, or have risk factors for it, seek your healthcare provider’s medical advice before going on sildenafil.

 

What are the side effects of Vardenafil?

Vardenafil has common side effects similar to sildenafil, such as:

 

• Headaches
• Nasal congestion
• Facial redness/flushing
• Dyspepsia (heartburn)
• Nausea
• Dizziness
• Light-headedness
• Back pain
• Flu-like symptoms

 

Vardenafil can also cause changes in color perception and raises your NAION risk. Like Sildenafil, these changes are generally temporary. Existing clinical trials do show that vision-related side effects may be lower with vardenafil than with sildenafil. However, other studies show that visual side effects may be the same between both drugs.

Some individuals who take vardenafil may experience prolonged QT or a slowing of some of the heart’s electrical pathways that may lead to changes in the person’s heart rhythm. People taking drugs that affect QT intervals or those with a history of QT prolongation may develop further prolongations.

 

 

What are the drug interactions between Sildenafil and Vardenafil?

 

Talk to your healthcare provider before going on an ED drug regimen. Share your medical history, including any supplements or prescription drugs you’re currently taking to reduce the risk of adverse drug interactions.

Since sildenafil and vardenafil are both PDE-5 inhibitor drugs, they have similar interaction warnings. 

One of the most dangerous interactions with PDE-5 inhibitors is the risk of developing a massive drop in blood pressure, particularly when you take them with nitrates. Nitrates are often used to treat chest pain and other cardiovascular conditions. Don’t take nitrates with PDE-5 inhibitors because they can cause fatal, extreme drops in blood pressure.

Likewise, individuals taking antihypertensives, such as alpha-blockers to reduce their blood pressure or treat prostate health concerns like prostate enlargement should exercise caution when taking sildenafil or vardenafil. Antihypertensives reduce blood pressure as do ED drugs, so combining both may lead to an extreme decrease in blood pressure.

Taking sildenafil or vardenafil if you are taking riociguat, a treatment for pulmonary arterial hypertension may also cause a serious drop in blood pressure.

 

Moreover, certain drugs that inhibit the CYP3A4 enzyme (such as ketoconazole, erythromycin, and ritonavir among others)  may affect the concentration of sildenafil or vardenafil in your bloodstream, increasing your risk of developing side effects. Drinking grapefruit juice may also interfere with this enzyme, affecting sildenafil or vardenafil drug concentrations.

 

Sildenafil and vardenafil may have other potential drug interactions. Consult your healthcare provider or pharmacist if you have any additional questions about either drug.