Sildenafil vs Viagra: same drug, generic vs brand

The short answer: sildenafil and Viagra are the same drug. Viagra is the brand name for sildenafil citrate tablets, approved for erectile dysfunction. [1] Generic sildenafil tablets for erectile dysfunction carry the same active ingredient and the same 25, 50, and 100 mg strengths. [2] FDA requires generics to have the same active ingredient, strength, dosage form, and route as the brand and to be bioequivalent to it. [3] The one real source of confusion is that sildenafil is also sold, as Revatio and its generics, for a different disease at a different dose. [4]

Sildenafil is not a peptide. We cover it because it belongs to the standard drug class that sexual health peptides such as PT-141 are compared with. This page reports FDA label facts. It is not a substitute for a prescriber, who needs to check your heart health and medications first.

What is the difference between sildenafil and Viagra?

The difference is the name on the box and the manufacturer, not the medicine.

• Active ingredient. Both contain sildenafil citrate, a phosphodiesterase-5 (PDE5) inhibitor. [1] [2]
• Approval standard. A generic must match the brand in active ingredient, strength, dosage form, and route of administration, be manufactured to the same standards, and be bioequivalent. FDA states that approved generics work the same way and have the same risks and benefits as the brand. [3]
• Label. A generic label is the same as the brand's, with certain exceptions. [3] The indication, dose, warnings, and contraindications you read below apply to both.
• Appearance and cost. Generics can look different, and they tend to cost less because they do not repeat the brand's clinical trials. [3]

Sildenafil 20 mg, Revatio, and pulmonary hypertension

Revatio is sildenafil approved for pulmonary arterial hypertension (PAH), high blood pressure in the arteries of the lungs, in adults and in children aged 1 to 17. The adult dose is 20 mg three times a day, with titration up to 80 mg three times a day if needed. [4] Generic 20 mg sildenafil tablets carry the same PAH indication. [5]

The approval rests on the SUPER-1 trial, in which 278 people with symptomatic PAH were randomized to placebo or sildenafil 20, 40, or 80 mg three times daily for 12 weeks. All doses improved the distance walked in six minutes, by 45 to 50 meters more than placebo. [7]

So "sildenafil 20 mg" and "Viagra" are the same molecule approved for different diseases. The Viagra label says the safety of combining Viagra with Revatio, other sildenafil products for PAH, or other PDE5 inhibitors has not been studied, that such combinations may further lower blood pressure, and that they are not recommended. [1]

Viagra label dose for erectile dysfunction

Sildenafil is FDA approved, so its label dose is public information. For most patients, the recommended dose is 50 mg taken as needed about 1 hour before sexual activity, though it can be taken from 30 minutes to 4 hours before. Based on effect and tolerance, the dose can be raised to a maximum of 100 mg or lowered to 25 mg, and it should be taken no more than once a day. It can be taken with or without food. [1]

The label recommends considering a 25 mg starting dose for people over 65, those with liver impairment or severe kidney impairment, and those taking strong CYP3A4 inhibitors or erythromycin. People on an alpha-blocker should be stable on it first and start at 25 mg. With ritonavir, the maximum is 25 mg in 48 hours, because ritonavir raised sildenafil blood levels 11-fold. [1]

How well sildenafil works

The pivotal trials were published in 1998. In a 12 week flexible-dose study, 69% of attempts at intercourse were successful in men taking sildenafil, compared with 22% in men on placebo. In a separate 24 week study of 532 men, higher doses produced greater improvement in erectile function. [6]

The American Urological Association's guideline says men should be told about every treatment that is not contraindicated for them, as potential first-line options, and choose through shared decision-making. [8] Our erectile dysfunction page summarizes the standard of care alongside the peptide evidence.

Sildenafil side effects

Because generic sildenafil and Viagra are the same drug, they share the same side effects.

Common side effects. In flexible-dose trials of Viagra (734 men on the drug, 725 on placebo), the adverse reactions reported by at least 2% of men and more often than on placebo were [1]:

• Headache: 16% versus 4% on placebo
• Flushing: 10% versus 1%
• Indigestion (dyspepsia): 7% versus 2%
• Nasal congestion: 4% versus 2%
• Abnormal vision: 3% versus 0%, mostly a mild, temporary color tinge, light sensitivity, or blurred vision
• Back pain, dizziness, and rash: 2% each

At the higher doses used for pulmonary hypertension, side effects are more frequent. In SUPER-1, headache affected 46% of patients on 20 mg three times a day versus 39% on placebo, and flushing, indigestion, diarrhea, and limb and muscle pain were also more common on the drug. [4]

Serious warnings. The label tells patients to [1]:

• Get emergency treatment for an erection lasting more than 4 hours (priapism).
• Stop the drug and seek care for sudden loss of vision in one or both eyes, which could be a sign of non-arteritic anterior ischemic optic neuropathy (NAION).
• Stop the drug and seek prompt care for a sudden decrease or loss of hearing.
• Use caution with alpha-blockers or other blood pressure drugs, since the combination can cause low blood pressure.

It also says sexual activity carries a potential cardiac risk for people with existing heart disease, and that Viagra should not generally be used by men for whom sexual activity is inadvisable because of their cardiovascular status. [1]

The nitrate contraindication

This is the most important safety rule for sildenafil. It is contraindicated in anyone using nitric oxide donors, such as organic nitrates or nitrites, in any form, whether regularly or only occasionally, because sildenafil increases their blood pressure lowering effect. [1] Nitrates are common heart medicines for chest pain, and the label says it is unknown when nitrates can be given safely after a dose of sildenafil. [1]

Sildenafil is also contraindicated with guanylate cyclase stimulators such as riociguat, and in anyone allergic to sildenafil. [1] The PAH form carries the same nitrate and riociguat contraindications. [4]

Where peptides fit

Two peptides are sometimes promoted for erections. Neither replaces sildenafil.

• Bremelanotide (PT-141). In a randomized trial of men who had not responded to sildenafil, 33.5% of those given bremelanotide had positive results versus 8.5% on placebo, with more drug-related side effects. [9] Its FDA approval, as Vyleesi, covers only premenopausal women with low sexual desire. [10] See the PT-141 page.
• Melanotan II. In a 10 man crossover study, it produced erections in 8, with nausea and yawning as side effects. [11] It is unapproved, sold as an unregulated injectable, and linked to priapism in case reports. [12] Are peptide injections safe explains what is unknown about products like it. See melanotan II and the PT-141 vs melanotan II comparison.

For desire and arousal problems in women and men, the sexual dysfunction page grades each option.

Buying sildenafil safely

Sildenafil is a prescription drug in the United States. FDA's BeSafeRx campaign explains how to tell a legitimate online pharmacy from an illegal one; the safest route is a prescription filled at a state-licensed pharmacy. [13] A prescriber also checks for nitrates, alpha-blockers, and heart conditions, the issues behind the label's most serious warnings.

The takeaway

Sildenafil vs Viagra is a choice between a generic and a brand of the same medicine, held to the same FDA standard, with the same side effects. The 20 mg tablets are the pulmonary hypertension version, taken on a different schedule, and should not be combined with the erectile dysfunction version. Whatever the name on the label, never take sildenafil with nitrates.