Sildenafil vs Viagra: What’s the difference?
- How sildenafil and Viagra are pharmacologically identical
- The regulatory process behind generic medicines in the UK
- Price comparison: What you can expect to pay for branded vs generic medicines in 2026
- Viagra Connect vs prescription sildenafil: The important distinction between OTC and prescription versions
- How to access both safely
Sildenafil is Viagra: the direct answer
Sildenafil citrate is the active ingredient in Viagra. When Pfizer developed Viagra in the 1990s, sildenafil was the molecule they discovered worked for erectile dysfunction. Pfizer patented the drug under the brand name Viagra, meaning they were the only company permitted to manufacture and sell it for a defined period.
When Pfizer's UK patent expired in 2013, other manufacturers were permitted to produce sildenafil under its generic name. The result is that dozens of MHRA-approved sildenafil tablets are now available in the UK, all containing the same active ingredient at the same doses, all subject to the same regulatory standards, and all producing the same clinical effect.
Good to know
The NHS actively encourages prescribing generic sildenafil over branded Viagra on cost-effectiveness grounds. NHS guidance on generic medicines is clear that a generic approved by the MHRA is therapeutically equivalent to its branded equivalent.
Brand vs generic: How it works in the UK
When a pharmaceutical company develops a new medicine, it is granted a patent that gives it exclusive rights to manufacture and sell that drug for a set period, typically around 20 years from the original patent filing date. During this period, the brand version is the only option available.
Once the patent expires, other manufacturers can apply to the MHRA to produce a generic version. To receive approval, they must demonstrate that their product contains the same active ingredient at the same dose and that it is bioequivalent, meaning it is absorbed by the body in the same way and produces the same blood levels as the original.
Generic sildenafil has been MHRA-approved in the UK since 2013. Every generic sildenafil tablet on the UK market has gone through this process. The tablet may look different, have a different name, or come from a different manufacturer, but the medicine inside is the same.
Good to know
Generic medicines may contain different inactive ingredients (fillers, coatings, colourings) from the branded version. These do not affect how the medicine works, but in very rare cases a person may have a sensitivity to a specific inactive ingredient.
If you notice a difference in how you feel after switching, mention it to your prescriber.
Are the effects the same?
Yes. Because generic sildenafil and Viagra contain the same active ingredient at the same dose, the effects are the same. The onset of action, duration, efficacy, and side effect profile are all equivalent.
Both work by inhibiting PDE5, the enzyme that breaks down cGMP in the smooth muscle of the penis. This increases blood flow during arousal and supports the ability to achieve and maintain an erection. A 50 mg tablet of generic sildenafil will produce the same pharmacological effect as a 50 mg Viagra tablet.
Why choose generic sildenafil over branded Viagra?
For the overwhelming majority of men, the answer comes down to one thing: cost.
Generic sildenafil is significantly cheaper than branded Viagra. As a rough guide for UK private prescription pricing in 2026:
| Product | Typical cost per tablet (100 mg) |
|---|---|
| Branded Viagra (100 mg) | £15 to £25 per tablet |
| Generic sildenafil (100 mg) | £1 to £5 per tablet |
Prices are indicative and vary between providers. Always confirm current pricing with your chosen GPhC-registered provider.
For a man taking sildenafil regularly, the cost difference over a year is significant. Given that the clinical effect is identical, there is no medical reason to pay a premium for the branded version.
Availability is another practical consideration. Generic sildenafil is widely stocked across UK pharmacies and regulated online providers, whereas branded Viagra may be less consistently available in all settings.
Why might someone still prefer branded Viagra?
There are a few reasons some men still choose Viagra over generic sildenafil, none of which are related to efficacy.
Brand familiarity is the most common reason. If you have used Viagra successfully for years, there can be a psychological reassurance in the consistency of the packaging, appearance, and experience. For some men, this familiarity itself contributes to confidence, which is not a trivial consideration when treating erectile dysfunction.
Perception of quality is another factor, though it is not supported by clinical evidence. The regulatory requirements for MHRA-approved generic sildenafil are rigorous, and there is no clinical basis for assuming a branded tablet is superior.
If brand familiarity matters to you, that is a valid personal preference. If efficacy and value are the priority, generic sildenafil delivers both.
Viagra Connect: The OTC option
One important distinction is worth understanding clearly, that not all sildenafil requires a prescription.
Prescription sildenafil (available in 25 mg, 50 mg, and 100 mg) requires a valid prescription from a registered prescriber. This applies to both generic sildenafil and branded Viagra at these doses.
Viagra Connect is a 50 mg sildenafil tablet that has been approved by the MHRA for sale without a prescription (over the counter) in UK pharmacies since 2018. It is available from pharmacists who conduct a brief suitability check before supplying it.
| Product | Dose | Prescription required? | Where available |
|---|---|---|---|
| Generic sildenafil | 25 mg, 50 mg, 100 mg | Yes | GP, online clinic, pharmacy |
| Branded Viagra | 25 mg, 50 mg, 100 mg | Yes | GP, online clinic, pharmacy |
| Viagra Connect | 50 mg | No | Pharmacy (after suitability check) |
Viagra Connect is only available in 50 mg. If you need a different dose, or if the pharmacist's suitability assessment identifies a reason you should not take it without further medical review, a prescription route is required.
Important!
Viagra Connect is not suitable for men taking nitrate medicines, certain antihypertensives, or those with specific cardiovascular conditions.
How to access sildenafil safely in the UK
There are three main routes to accessing sildenafil in the UK. Each differs in terms of convenience, cost and the level of clinical oversight involved.
Via your GP
Your GP can prescribe generic sildenafil on the NHS where it meets prescribing criteria. NHS prescriptions are subject to the standard prescription charge in England (currently £9.90 per item), and are free in Scotland, Wales, and Northern Ireland for eligible patients.
Via a pharmacist (Viagra Connect only)
For the 50 mg OTC dose, a pharmacist can supply Viagra Connect after a brief consultation to confirm suitability. No prescription is needed, but the pharmacist will ask about your medical history and current medicines.
Via a regulated online clinic
Private online clinics connect you with UK-registered prescribers who can assess your suitability and issue a private prescription for generic sildenafil at any licensed dose. DoktorABC connects UK patients with licensed prescribers and GPhC-registered pharmacies for private ED treatment, with a medical assessment completed online.
Important!
Always ensure any online provider you use is registered with the GPhC (gphc.org.uk) and requires a genuine medical assessment before issuing a prescription.
Sildenafil is a prescription-only medicine for good reason, and any site offering it without a prescriber review is not operating legally or safely.
Final thoughts
Sildenafil and Viagra are the same medicine. For most men, generic sildenafil offers an identical clinical outcome at a fraction of the cost of the branded version, and the NHS and MHRA both support this position. Whether you access it via your GP, a pharmacist, or a regulated online clinic, what matters is that you receive a proper medical assessment before starting, use it as directed, and know when to seek advice.
If you have questions about whether sildenafil is right for you, or what dose is appropriate for your circumstances, a UK-registered prescriber is the right first port of call.
FAQ
Is sildenafil as good as Viagra?
Yes. Sildenafil is the active ingredient in Viagra. Generic sildenafil approved by the MHRA is bioequivalent to branded Viagra, meaning it produces the same blood levels, the same clinical effect, and the same side effect profile. The NHS prescribes generic sildenafil as the first-line option on cost-effectiveness grounds.
What is the difference between Viagra and sildenafil?
Viagra is the brand name; sildenafil is the generic name for the same active ingredient. The difference is in the manufacturer, packaging, and price, not in the medicine itself. Both are available in 25 mg, 50 mg, and 100 mg doses and require a prescription except for Viagra Connect 50 mg.
Is generic sildenafil safe?
Yes, when obtained from a GPhC-registered pharmacy following a medical assessment. All MHRA-approved generic sildenafil meets the same regulatory standards as branded Viagra. Buying from unregulated sources carries risks of counterfeit or substandard products.
Can I switch from Viagra to generic sildenafil?
Yes. Because they contain the same active ingredient at the same dose, switching is straightforward. There is no clinical reason to titrate or adjust when switching between the brand and its generic equivalent. If you have any concerns, mention the switch to your prescriber.
Is Viagra Connect the same as prescription sildenafil?
Viagra Connect contains the same active ingredient (sildenafil 50 mg) as prescription sildenafil. The difference is that it is available without a prescription following a pharmacist suitability check, whereas prescription sildenafil requires a prescriber assessment and is available in additional doses (25 mg and 100 mg).
The DoktorABC medical advisory board
Dr. Roland Ruiken
Medical advisor, Norway
Dr. Viktor Simunovic
Medical advisor, Croatia