Is Viagra (sildenafil) safe? What you need to know

An estimated 30 million people in the United States live with erectile dysfunction (ED). Contrary to popular belief, ED doesn’t just impact older adults–roughly 1 in 4 people newly diagnosed with ED are younger than 40. No matter your age, if you’re affected by ED, you’ve probably heard of Viagra. 

Viagra (sildenafil citrate) has been on the market since 1998, which is more than two decades ago, and it remains a safe and effective medication for treating erectile dysfunction when used as prescribed by a healthcare provider. Taking too much Viagra or taking Viagra too frequently, however, may increase your risk of side effects. If you’re considering talking to your doctor about “the little blue pill,” make sure you discuss your health history and additional medication with your healthcare provider.

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An estimated 30 million people in the United States live with erectile dysfunction (ED). Contrary to popular belief, ED doesn’t just impact older adults–roughly 1 in 4 people newly diagnosed with ED are younger than 40. No matter your age, if you’re affected by ED, you’ve probably heard of Viagra. 

Viagra (sildenafil citrate) has been on the market since 1998, which is more than two decades ago, and it remains a safe and effective medication for treating erectile dysfunction when used as prescribed by a healthcare provider. Taking too much Viagra or taking Viagra too frequently, however, may increase your risk of side effects. If you’re considering talking to your doctor about “the little blue pill,” make sure you discuss your health history and additional medication with your healthcare provider. 

Viagra and its generic alternative, sildenafil, are safe if you follow your healthcare provider’s instructions. That said, taking Viagra more frequently or using a higher dose than you are prescribed can be dangerous and lead to more side effects. Taking other medications or supplements may also affect how safe Viagra is for you. 

Like all prescription drugs dispensed in the United States, the treatment didn’t become available to the public for the treatment of ED until the FDA deemed Viagra safe and effective, following robust clinical trials and a thorough approval process. 

Erections are pretty complex, and many things can prevent them from working as easily as you might hope. To get an erection, your blood vessels that supply blood to your penis, as well as nerves throughout your body, need to work together. When you’re aroused (and sometimes when you’re not,) the blood vessels leading into the spongy tissues of the penis dilate or open up. This allows more blood to flow into the penis. If there are any issues with the nerves or the blood vessels involved in the process, it can result in less firm erections than you or your partner might like. 

 The active ingredient in Viagra is sildenafil, a type of drug called a PDE-5 inhibitor that improves blood flow to the penis. It works by blocking the effects of an enzyme called PDE-5 (phosphodiesterase-type 5), keeping the blood vessels open and allowing more blood flow to reach the penis, making for a stronger erection.

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Same active ingredient as the “Little Blue Pill” for up to 95% less

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Evidence suggests that long-term Viagra use is relatively safe. Complications are generally rare among people taking Viagra and its generic sildenafil as prescribed.

All medications come with a risk of certain side effects, though, and Viagra is no exception. According to the product label, the most common side effects are:

• Headache

• Facial flushing (redness)

• Stomach pain or discomfort (dyspepsia)

• Abnormal or blurred vision

• Nasal congestion

• Back pain

• Aching muscles

• Nausea

• Dizziness

• Rash

An erection lasting more than 4 hours (priapism) is an uncommon but serious side effect of Viagra and requires emergency medical attention to prevent permanent damage. 

Ultimately, your healthcare provider is your best source of medical advice and for knowing how to manage Viagra's side effects.

Luckily, most mild side effects of Viagra and its generic sildenafil disappear within a few hours of taking your medication. If you experience nausea or indigestion while taking Viagra, try taking the medication with a light snack (again, steer clear of high-fat foods that may lessen the effects of Viagra). If you experience headaches, dizziness, or flushing, turn off bright lights and lie down to rest. This will often relieve those side effects.

Alcohol may worsen the side effects of Viagra. If you’re struggling with pesky mild side effects, avoid drinking alcohol while taking Viagra.

Viagra is meant to be taken on an as-needed basis. You should take your medication exactly as prescribed at the recommended dose. The little blue pill comes in three dosage strengths (25 mg, 50 mg, and 100 mg). Your provider may adjust your dose based on how well it works or any side effects you may be experiencing. Regardless of your dose, you should only take a maximum of one dose of Viagra in any 24-hour period. You can take this prescription drug on an empty stomach or following a meal. However, if you eat a high-fat meal, it may take longer for Viagra to start working.

If you accidentally take more Viagra than your prescription calls for, contact your healthcare provider to avoid potential complications.

Knowing when to take Viagra is a key factor in determining how well the treatment will work for you. It’s meant to be taken on an as-needed basis about an hour before you plan to have sex. However, the treatment may be taken anywhere from 30 minutes to 4 hours before sexual activity.  If you’re looking for more spontaneity in your sex life, though, you can consider combination treatments like Ro Sparks, which contain a combination of two ED treatments: sildenafil and tadalafil. Instead of pills, Ro Sparks are dissolvable drops you place under your tongue. This allows the medication to enter your bloodstream directly, giving you an erection within 15 minutes on average. 

Viagra and its generic sildenafil will work slower or faster depending on you and your sex life—Viagra can only help you get hard and stay hard if you are already aroused, and it won’t work unless you are sexually stimulated. 

On average, Viagra works within one hour of taking the pill. If time is of the essence, taking the pill on an empty stomach may cause the medication to work faster. Conversely, avoid eating heavy, high-fat meals before taking Viagra. High-fat foods may make the drug work more slowly and lessen the effects.

ED affects both older and younger people alike. While Viagra is considered safe for most people with ED, some factors and health conditions may make people more prone to bad side effects. You should never take Viagra with nitrates or nitrates, as this drug combination can lead to a dangerous drop in blood pressure. People who should not take Viagra, or may be cautioned against taking it due to the risk of serious side effects, include:

• People with certain heart conditions that are considered too risky for sexual activity

• Those who take certain classes of medications, including alpha-blockers and antihypertensives

• People with a history of low blood pressure, irregular heartbeat, or heart failure

• Anyone who has experienced a stroke or heart attack in the past six months

The best way to know if Viagra is right for you is to speak to a healthcare provider about your concerns, especially if you have a heart condition. You can speak with a healthcare provider online right from the comfort of your home through Ro. A US-licensed doctor can evaluate your medical history and, if treatment is right for you, send you your medication right to your door. Learn more here.

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

January 16, 2024

Written by

Allison Gilchrist

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.