Generic Viagra is sildenafil citrate made by companies other than the original brand owner, and an FDA-approved generic must contain the same active ingredient, in the same strength and form, and work the same way in the body as brand-name Viagra. The real risk is not the approved generic itself but fake “generic Viagra” sold by unlicensed websites, which may contain too little, too much or the wrong drug. Buy it only with a prescription, from a licensed pharmacy, after a doctor has checked that sildenafil is safe for you; our erectile dysfunction treatment page explains the wider options.
Sources: FDA — Generic Drug Facts; J Sex Med (PubMed) — Internet-ordered Viagra (sildenafil citrate) is rarely genuine (Campbell et al., 2012)
- Approved generic Viagra (sildenafil) must match the brand’s active ingredient, strength, dosage form and route, and be bioequivalent to it.
- Generic Viagra tablets may differ in color, shape and inactive ingredients; that does not make them weaker.
- Revatio is also sildenafil, but in 20 mg tablets taken three times a day for pulmonary arterial hypertension. Never take Revatio and Viagra together.
- In a Pfizer-run test of 22 websites selling Viagra, 77% of the tablets received were counterfeit, with only 30–50% of the labeled dose.
- FDA’s BeSafeRx rule: use only a pharmacy that requires a prescription, is state-licensed, lists a physical address and has a pharmacist you can talk to.
- What generic Viagra actually is
- Is generic Viagra as good as the brand?
- Revatio vs Viagra: same molecule, different strengths
- How generic Viagra is taken
- Counterfeit generic Viagra: what testing has found
- “Herbal Viagra” and tainted supplements
- How to buy generic Viagra safely
- Who should not take generic Viagra
- When to see a doctor
- FAQs about generic Viagra
What generic Viagra actually is
Viagra is the brand name of sildenafil citrate, a phosphodiesterase type 5 (PDE5) inhibitor. During sexual arousal, nerves in the penis release nitric oxide, which raises a messenger molecule called cGMP and relaxes the smooth muscle of the erectile tissue so blood can flow in. Sildenafil slows the enzyme that breaks cGMP down, which makes erections easier to get and keep. It does not work without sexual stimulation.
Brand Viagra comes as blue, rounded, diamond-shaped film-coated tablets of 25 mg, 50 mg and 100 mg, stamped “VIAGRA” on one side and “VGR 25”, “VGR 50” or “VGR 100” on the other.
Source: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
Strictly speaking, there is no such thing as “generic Viagra”: Viagra is a trademark, so a legal generic is sold under its chemical name, sildenafil (or sildenafil citrate), with the maker’s own imprint. When people search for generic Viagra, they almost always mean these approved sildenafil tablets. A website that sells “generic Viagra” pills carrying the Viagra name is a warning sign in itself: in a study of 22 websites claiming to sell Pfizer’s Viagra, 90% also offered illegal “generic Viagra.”
Sources: J Sex Med (PubMed) — Internet-ordered Viagra (sildenafil citrate) is rarely genuine (Campbell et al., 2012); FDA — Generic Drugs: Questions & Answers
Generics, including generic Viagra, reach the market after the brand’s patents and marketing exclusivities expire, or after those patents are successfully challenged. They cost less mainly because their makers do not have to repeat the animal and clinical studies done for the original drug. FDA notes that a single generic competitor can cut prices by around 30%, and that with five competing generics prices can drop by nearly 85%.
Source: FDA — Generic Drug Facts
Is generic Viagra as good as the brand?
For an FDA-approved generic Viagra product, yes. To be approved, a generic must have the same active ingredient, strength, dosage form (for example a tablet) and route of administration (by mouth) as the brand. It must also be manufactured to the same strict standards, carry the same label information with limited exceptions, and be bioequivalent to the brand.
Bioequivalence means that the generic delivers the same amount of active ingredient into the bloodstream, at the same rate, as the brand. In practice, a 50 mg generic Viagra (sildenafil) tablet is expected to work the same way in your body as a 50 mg Viagra tablet. FDA also states that all approved drugs marketed in the U.S. must meet the same quality standards, wherever they are made, and the agency inspects manufacturing plants for good manufacturing practices before approval and keeps monitoring products once they are sold.
Sources: FDA — Generic Drug Facts; FDA — Generic Drugs: Questions & Answers
What can differ between brand and generic sildenafil
FDA generally allows minor differences in appearance, such as color, so a generic Viagra tablet will often be white or a different shade of blue, with a different shape and imprint. Inactive ingredients such as fillers, coatings and dyes may also differ. FDA says that in most cases these make no difference, but in a minority of patients inactive ingredients may affect tolerability or absorption. If you have a known allergy to a dye or filler, ask the pharmacist to check the product’s ingredient list.
Source: FDA — Generic Drugs: Questions & Answers
| Feature | Brand Viagra | FDA-approved generic sildenafil | Illegal “generic Viagra” online |
|---|---|---|---|
| Active ingredient | Sildenafil citrate | Sildenafil citrate (same) | Unknown; may be wrong, too little, too much or none |
| Strengths for ED | 25, 50, 100 mg | 25, 50, 100 mg | Whatever is printed, often inaccurate |
| Bioequivalence | Reference product | Must be shown to FDA | Never tested |
| Appearance | Blue diamond, “VGR” imprint | May differ in color and shape | Often copies the brand look |
| Prescription | Required in the U.S. | Required in the U.S. | Usually not asked for |
| Patient leaflet and warnings | Included | Included | Often missing |
Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; FDA — Generic Drug Facts; J Sex Med (PubMed) — Internet-ordered Viagra (sildenafil citrate) is rarely genuine (Campbell et al., 2012)
Revatio vs Viagra: same molecule, different strengths
Many men are surprised to find that sildenafil is sold under two brands. Viagra and generic Viagra treat erectile dysfunction. Revatio, and its generic versions, treats pulmonary arterial hypertension (PAH), a form of high blood pressure in the arteries of the lungs. Revatio is approved for adults and for children aged 1 to 17.
The molecule is the same, but the product is built for a different job. Revatio tablets contain 20 mg of sildenafil, and the usual adult dose is 20 mg three times a day, taken regularly rather than before sex. Revatio also comes as an oral suspension (10 mg/mL once reconstituted) and as an injection for hospital use.
Sources: DailyMed (FDA label) — REVATIO (sildenafil) prescribing information; MedlinePlus — Sildenafil
| Viagra (and generics) | Revatio (and generics) | |
|---|---|---|
| Condition treated | Erectile dysfunction | Pulmonary arterial hypertension |
| Tablet strengths | 25, 50, 100 mg | 20 mg |
| Usual schedule | As needed, about 1 hour before sex, max once a day | 20 mg three times a day, every day |
| Other forms | Tablets only | Oral suspension 10 mg/mL; injection |
| Combine with the other? | No | No: “Avoid use with Viagra or other PDE-5 inhibitors” |
Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; DailyMed (FDA label) — REVATIO (sildenafil) prescribing information
The safety message is simple: take only one sildenafil product at a time, whether Revatio, brand Viagra or generic Viagra. Both FDA labels advise against combining sildenafil with other PDE5 inhibitors, because the combination may lower blood pressure further, and MedlinePlus states that you should be treated with only one of these products at a time. If you already take Revatio for PAH, tell your doctor before any ED treatment is started. And because 20 mg tablets are labeled and dosed for a different condition, never build your own ED dose from them without a prescription that says exactly what to take.
Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; MedlinePlus — Sildenafil
How generic Viagra is taken
Generic Viagra (sildenafil) is taken in exactly the same way as the brand. For most men, the recommended starting dose is 50 mg, as needed, about 1 hour before sexual activity, although it can be taken anywhere from 30 minutes to 4 hours beforehand. Depending on effect and side effects, a doctor may raise the dose to a maximum of 100 mg or lower it to 25 mg. The maximum is one dose per day.
A 25 mg starting dose is suggested for men over 65, men with liver problems or severe kidney impairment, and men taking alpha-blockers, erythromycin or strong CYP3A4 inhibitors. With ritonavir, the label limits sildenafil to 25 mg in any 48-hour period.
Source: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
The EAU guidelines describe sildenafil as working from about 30–60 minutes after a dose for up to 12 hours. In a 24-week dose-response study, improved erections were reported by 56% of men on 25 mg, 77% on 50 mg and 84% on 100 mg, compared with 25% on placebo. Our guide to Viagra dosage covers timing, food and dose adjustments in more detail, and sildenafil side effects are the same for brand and generic.
Source: EAU Guidelines — Management of Erectile Dysfunction
Counterfeit generic Viagra: what testing has found
Counterfeit sildenafil sold as generic Viagra is a well-documented problem, and unregulated websites are a major route for fakes. WHO defines falsified medical products as those that deliberately misrepresent their identity, composition or source, and notes that substandard and falsified products are often sold online or in informal markets. WHO estimates that at least 1 in 10 medicines in low- and middle-income countries is substandard or falsified.
Source: WHO — Substandard and falsified medical products (fact sheet)
Test purchases show how real the problem is for anyone shopping for Viagra or generic Viagra online. In 2011, Pfizer researchers ordered from 22 websites that appeared at the top of search results for “buy Viagra” and claimed to sell the genuine product:
- No website required a prescription or a health screening questionnaire.
- 17 of 22 samples (77%) were counterfeit, 4 (18%) were authentic and 1 was an illegal generic.
- Counterfeit tablets contained only 30% to 50% of the sildenafil dose printed on the label.
- The four “Canadian” pharmacies did not ship from a Canadian address; half of all shipments came from Hong Kong.
- Counterfeits lacked patient leaflets and safety warnings.
A 2010 review of counterfeit PDE5 inhibitors found doses ranging from 0% to more than 200% of the labeled amount. In one analysis, only 10.1% of samples sold as “Viagra 100 mg” were within 10% of the stated strength. Contaminants reported in fakes included talc, commercial paint, printer ink, amphetamine, paracetamol and the antibiotic metronidazole.
The same review describes an outbreak in Singapore in which counterfeit tadalafil and “herbal” ED products were contaminated with glyburide, a powerful diabetes drug. Of 150 people without diabetes admitted to hospital with low blood sugar, seven were in a coma and four later died.
“Herbal Viagra” and tainted supplements
Products marketed as “natural” or “herbal Viagra” are not generic Viagra at all. FDA regularly warns that sexual enhancement products sold online and in shops may contain hidden drug ingredients, pose a serious health risk and may not work. The agency adds that its notification list covers only a small fraction of the contaminated products on the market.
Source: FDA — Sexual Enhancement and Energy Product Notifications
A hidden PDE5 inhibitor is especially dangerous for men who take nitrates for chest pain, because the combination can cause a severe fall in blood pressure; the sildenafil label lists nitrates in any form as a contraindication. Since the label of a tainted supplement does not reveal the drug, the user cannot know the risk. If you are curious about non-drug approaches, our article on natural remedies for erectile dysfunction separates evidence from marketing.
Source: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
How to buy generic Viagra safely
FDA’s BeSafeRx campaign exists to help people buy prescription medicines, including generic Viagra, online safely. According to FDA, there are roughly 35,000 active online pharmacies at any time, and the National Association of Boards of Pharmacy estimates that only about 5% of them comply with U.S. pharmacy laws and practice standards. Fake medicines from rogue sites may contain the wrong ingredients, too little, too much or no active ingredient at all, or other harmful substances.
Sources: FDA — BeSafeRx: Your Source for Online Pharmacy Information; FDA BeSafeRx — Frequently Asked Questions
| Signs of a safe online pharmacy | Warning signs of an unsafe one |
|---|---|
| Always requires a doctor’s prescription | Does not require a prescription |
| Licensed with a state board of pharmacy | Not licensed in the U.S. or by your state board |
| Has a licensed pharmacist to answer your questions | No pharmacist available |
| Gives a physical U.S. address and phone number | Sends medicine that looks different from your local pharmacy’s, or in damaged, foreign-language or expired packaging |
| Protects your personal and financial data | Deep discounts or prices that seem too good to be true; charges for items never ordered |
Source: FDA BeSafeRx — Considering an Online Pharmacy?
A practical checklist
- Get a prescription first. A doctor confirms that sildenafil is right for you, checks your heart health and medicines, and chooses the dose.
- Verify the pharmacy. In the U.S., check the pharmacy against your state board of pharmacy database through FDA’s locator. FDA’s advice is blunt: if your online pharmacy is not listed, do not use it.
- Check what arrives. Compare the tablets and imprint with the product description and the pharmacist’s label, and make sure the patient leaflet is included. Packaging that is broken, in a foreign language or without an expiry date is a red flag.
- Report problems. Report suspected unsafe websites to FDA and side effects to FDA’s MedWatch program, or to your national medicines regulator outside the U.S.
Sources: FDA BeSafeRx — Locate a State-Licensed Online Pharmacy; FDA — How to Buy Medicines Safely From an Online Pharmacy
Rules for buying generic Viagra differ by country. In the UK, for example, the NHS explains that sildenafil is mostly prescription-only, but men can buy it from a pharmacy for erection problems after speaking with a pharmacist. Wherever you live, the safest route is the regulated one: a licensed prescriber and a licensed pharmacy.
Source: NHS — Sildenafil: a medicine for erection problems
Who should not take generic Viagra
Because generic Viagra and brand Viagra are the same drug (sildenafil), the same contraindications apply. Do not take either if you:
- Use nitrates or other nitric oxide donors in any form, including nitroglycerin and “poppers”.
- Take riociguat or another guanylate cyclase stimulator.
- Have had an allergic reaction to sildenafil or any ingredient of the tablet.
Source: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
The NHS adds that sildenafil may not be suitable if you have recently had a heart attack or stroke, have low or uncontrolled high blood pressure, liver or kidney problems, sickle cell anemia, leukemia or multiple myeloma, a curved penis that makes erections painful, or have ever lost vision from reduced blood flow to the optic nerve. A doctor should weigh these before prescribing. If you are not sure whether your erection problems need a fuller work-up, an erectile dysfunction test can help find the cause.
Source: NHS — Sildenafil: a medicine for erection problems
When to see a doctor
See a doctor before you start any sildenafil product, brand or generic Viagra, because erectile dysfunction can be an early sign of heart disease, diabetes or hormone problems. Book a review if sildenafil does not work after several attempts at the right dose; the EAU guidelines advise checking that the man has been using a licensed medication before calling it a treatment failure, which matters if your tablets came from an unverified source.
Source: EAU Guidelines — Management of Erectile Dysfunction
Get emergency help for any of these red flags after taking sildenafil or any product sold as sildenafil:
- An erection lasting more than 4 hours.
- Chest pain, fainting or severe dizziness during or after sex.
- Sudden loss of vision in one or both eyes, or sudden hearing loss.
- Signs of low blood sugar, such as sweating, shakiness or confusion, especially after an online or “herbal” product.
Sources: DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information; Int J Clin Pract (PMC) — Counterfeit phosphodiesterase type 5 inhibitors pose significant safety risks (Jackson et al., 2010)
If you would like a confidential assessment, our urologist-andrologist can review your health and recommend a safe, prescribed treatment; message us on WhatsApp or read about our erectile dysfunction treatment options.
FAQs about generic Viagra
Is generic Viagra the same as Viagra?
An FDA-approved generic Viagra (sildenafil) tablet contains the same active ingredient in the same strength and dosage form as Viagra and must be bioequivalent, meaning it delivers the same amount of drug into the body at the same rate. It may look different and use different inactive ingredients, but it is expected to work the same way and carries the same warnings.
Sources: FDA — Generic Drug Facts; FDA — Generic Drugs: Questions & Answers
Why does generic sildenafil look different from the blue pill?
FDA generally allows minor differences in appearance, such as color and shape, between generic and brand-name drugs. Brand Viagra is a blue, diamond-shaped tablet marked “VGR”; generic tablets carry their own maker’s imprint. A different look on its own is not a problem, but pills that copy the Viagra name and logo while being sold as “generic” are a warning sign.
Sources: FDA — Generic Drugs: Questions & Answers; DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
Can I use Revatio 20 mg tablets instead of Viagra?
Revatio and its generics contain sildenafil too, but they are 20 mg tablets approved for pulmonary arterial hypertension and taken three times a day. Do not turn them into an ED dose on your own or combine them with Viagra; any use for ED must be decided and written by your doctor.
Sources: DailyMed (FDA label) — REVATIO (sildenafil) prescribing information; DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
Is it safe to buy generic Viagra online?
Buying generic Viagra online can be safe if the online pharmacy is legitimate. FDA advises using only pharmacies that require a prescription, are licensed by a state board of pharmacy, list a physical address and phone number, and have a licensed pharmacist available. Sites that sell sildenafil without a prescription, offer prices that look too good to be true or ship from abroad should be avoided.
Sources: FDA BeSafeRx — Considering an Online Pharmacy?; FDA BeSafeRx — Frequently Asked Questions
How common is fake Viagra online?
Very common on unregulated sites. In a test purchase from 22 websites that claimed to sell genuine Viagra, 77% of the tablets received were counterfeit and contained only 30–50% of the labeled sildenafil dose. A separate review found counterfeit PDE5 inhibitor doses ranging from none to more than double the label, plus contaminants such as talc, paint and printer ink.
Sources: J Sex Med (PubMed) — Internet-ordered Viagra (sildenafil citrate) is rarely genuine (Campbell et al., 2012); Int J Clin Pract (PMC) — Counterfeit phosphodiesterase type 5 inhibitors pose significant safety risks (Jackson et al., 2010)
How do I check whether an online pharmacy is licensed?
In the U.S., use FDA’s BeSafeRx “Locate a State-Licensed Online Pharmacy” tool, which links to state board of pharmacy license databases. If the pharmacy is not listed, FDA says not to use it. Then confirm it requires a prescription, gives a U.S. street address and phone number, and has a licensed pharmacist you can speak to. Outside the U.S., check your national pharmacy regulator.
Source: FDA BeSafeRx — Locate a State-Licensed Online Pharmacy
What should I do if I think I received counterfeit sildenafil?
Stop taking them and keep the packaging. In the U.S., report the website to FDA and any side effects to MedWatch; elsewhere, report to your national medicines regulator. See a doctor for a proper prescription, and seek urgent care for chest pain, an erection lasting more than 4 hours, vision loss or signs of low blood sugar.
Sources: FDA — How to Buy Medicines Safely From an Online Pharmacy; DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
Medically reviewed by Assoc. Prof. Dr. Zülfü Sertkaya, urologist and andrologist (FEBU), Istanbul. Last reviewed: November 2026.
This article is for general information and does not replace an individual consultation with a qualified doctor.
- FDA — Generic Drug Facts
- FDA — Generic Drugs: Questions & Answers
- DailyMed (FDA label) — VIAGRA (sildenafil citrate) prescribing information
- DailyMed (FDA label) — REVATIO (sildenafil) prescribing information
- MedlinePlus — Sildenafil
- NHS — Sildenafil: a medicine for erection problems
- EAU Guidelines — Management of Erectile Dysfunction
- FDA — BeSafeRx: Your Source for Online Pharmacy Information
- FDA BeSafeRx — Considering an Online Pharmacy?
- FDA BeSafeRx — Frequently Asked Questions
- FDA BeSafeRx — Locate a State-Licensed Online Pharmacy
- FDA — How to Buy Medicines Safely From an Online Pharmacy
- WHO — Substandard and falsified medical products (fact sheet)
- J Sex Med (PubMed) — Internet-ordered Viagra (sildenafil citrate) is rarely genuine (Campbell et al., 2012)
- Int J Clin Pract (PMC) — Counterfeit phosphodiesterase type 5 inhibitors pose significant safety risks (Jackson et al., 2010)
- FDA — Sexual Enhancement and Energy Product Notifications
