If you are comparing avanafil vs Viagra, the short answer is that avanafil usually starts working faster, often within 15 to 30 minutes, while Viagra (sildenafil) more often takes 30 to 60 minutes, but both are UK-licensed PDE5 inhibitors with similar effectiveness for many men when prescribed appropriately. If you have been prescribed one erectile dysfunction tablet and are wondering whether the other medicine might suit you better, you are asking a reasonable question.
For adult men in the UK looking into private prescription treatment for erectile dysfunction, the practical differences usually come down to timing, duration, the effect of food and alcohol, side effects, safety, cost, and how each medicine fits your medical history and routine rather than whether they work at all. This guide compares avanafil with sildenafil clearly and without declaring a winner, so you can judge which option may suit you better before seeking medical advice or a prescription.
What Avanafil and Sildenafil Have in Common as Erectile Dysfunction Medication
Both are phosphodiesterase type 5 inhibitors. In a normal erection, nitric oxide is released, which triggers a chain reaction involving cGMP, relaxing the smooth muscles in the penile blood vessels and increasing blood flow to the erectile tissue. PDE5 is the enzyme that breaks cGMP down. By slowing that breakdown, both medicines help achieve and maintain erections by increasing blood flow during sexual stimulation.
The practical consequence matters: both drugs are oral medicine used in the treatment of erectile dysfunction, but neither works unless you are sexually stimulated, and neither cures the underlying condition. They support a physiological process rather than replacing it. Sexual stimulation is still required for either medicine to work.
Both are prescription-only medicines in the UK, with one exception noted later regarding Viagra Connect.
Brand and Generic Sildenafil Names Explained
The terminology can be confusing, and several of the searches that bring people to this page reflect that, especially when comparing Avanafil and Sildenafil as two medications with different brand names.
| Active ingredient | UK brand | US brand | Generic available in UK |
|---|---|---|---|
| Avanafil | Spedra | Stendra | Yes |
| Sildenafil | Viagra | Viagra | Yes |
Here, "Viagra sildenafil" simply means that brand name Viagra contains sildenafil citrate. So "Spedra vs Viagra", "Stendra vs Viagra", "avanafil vs sildenafil" and "generic Spedra vs generic Viagra" are all versions of the same comparison. If you have seen the spelling "adenafil" or the brand "Avarante", these are most likely misspellings or repackaged references to avanafil, and you should check the active ingredient on any pack before use.
The generic and branded versions of each drug work in exactly the same way. For Viagra, the generic version is sildenafil, so choosing between branded and generic comes down to personal preference and price, while brand name Viagra usually costs more.
The Difference Between Avanafil and Sildenafil
Onset of action
This is the most meaningful practical difference between a fast-acting ED (Erectile dysfunction) medication and a slower-starting option. Avanafil typically begins working within around 15 to 30 minutes, although response times vary between individuals, so avanafil may be taken closer to sexual activity than sildenafil, whereas sildenafil is generally taken around 30 to 60 minutes before sexual activity as oral tablets taken in advance.
That difference has been measured directly rather than just estimated in clinical trials. In a randomised, double blind, multicentre trial of 220 patients comparing avanafil with sildenafil, avanafil demonstrated a significantly faster onset of action on the modified Sexual Encounter Profile 1 measure, at 84.8% compared with 28.2% for sildenafil, indicating faster onset. The same trial found avanafil non-inferior on the International Index of Erectile Function score at week 4 and showed statistically higher scores at weeks 8 and 12 in that study, with similar findings also discussed across clinical studies.
A note on that evidence: This study was sponsored and funded by Zydus Healthcare Limited, the manufacturer of one of the comparator products. Industry sponsorship does not invalidate a trial, but it is a relevant caveat when weighing a superiority claim, and we mention it because it is relevant to consider when interpreting the findings.
Duration
The two medicines have a broadly similar duration of action. Sildenafil typically remains active for around four to six hours. Avanafil remains effective for a comparable window, with some sources reporting up to six hours. Neither typically provides the prolonged duration of action associated with tadalafil, often called the weekend pill because of its longer duration, which is the relevant point if you have been comparing avanafil with tadalafil rather than with sildenafil.
Both medicines may remain in the body for around 24 hours even after their effects have worn off, which is why neither should be taken more than once in any 24-hour period.
Food and alcohol
Avanafil may be taken with or without food. The manufacturer notes that onset may be delayed if it is taken with food, compared with taking it on an empty stomach. Sildenafil is generally more affected : after a heavy or high-fat meal, its onset may be delayed to 90 to 120 minutes.
Both treatments can be affected by excessive alcohol, which may reduce effectiveness and increase the likelihood of side effects.
Side effect profile
Stendra (avanafil) and Viagra (sildenafil) have similar side effects because they work in the same way.
Common side effects include headache, facial flushing, nasal congestion, indigestion and dizziness.
Some studies suggest that headaches and flushing may be reported less often with avanafil than with sildenafil, but both medicines are generally well tolerated and the differences are relatively small.
If avanafil makes you feel dizzy or affects your vision, do not drive, cycle or operate machinery until you feel well again.
Although rare, seek urgent medical attention if you develop chest pain, a sudden loss of vision or hearing, or an erection lasting more than 4 hours (priapism). Always read the patient information leaflet supplied with your medicine and report suspected side effects through the MHRA Yellow Card Scheme.
Comparison summary
| Feature | Avanafil (Spedra) | Sildenafil (Viagra) |
|---|---|---|
| Drug class | PDE5 inhibitor | PDE5 inhibitor |
| Typical onset | 15 to 30 minutes | 30 to 60 minutes |
| Typical duration | 4 to 6 hours | 4 to 6 hours |
| Effect of food | Onset may be delayed | Onset delayed more markedly after a heavy meal |
| UK licensed strengths | 50 mg, 100 mg, 200 mg (three doses) | 25 mg, 50 mg, 100 mg |
| Maximum frequency | Once in 24 hours | Once in 24 hours |
| UK availability | Prescription only | Prescription, 50 mg available as Viagra Connect |
| Relative cost | Higher | Lower, widely generic |
| Length of clinical record | Licensed since 2013 | Licensed since 1998 |
Is Avanafil Better Than Viagra?
This is among the most common questions asked about the pair, and the honest answer is that "better" depends entirely on what you need from the medicine.
Across the PDE5 class, response rates are broadly comparable, and clinical studies have reported high response rates with sildenafil, although effectiveness varies between individuals, so the choice is generally made on lifestyle fit rather than on raw efficacy. Both are prescription erectile dysfunction treatments, and the right option is usually chosen based on timing, food sensitivity, cost, and how you respond.
Avanafil may suit you if speed matters, if you have found sildenafil's food sensitivity inconvenient, or if sildenafil has not provided a satisfactory response. Sildenafil may suit you if cost is a significant factor, if you value the longer accumulated safety record, or if it already works well for you.
Neither is the correct answer for everyone. Treatment suitability depends on an individual clinical assessment, and your prescriber will determine which option is appropriate for your circumstances. Individual responses vary.
Safety, Side Effects, Interactions and Who Should Not Take These Medicines
This section applies to both drugs and is the part of the comparison that carries the most weight.
Absolute contraindication.
Stendra and Viagra should not be taken if you use nitrate medicines or nitric oxide donors, including amyl nitrite ("poppers"), because the combination can cause a dangerous drop in blood pressure. They are also not suitable for people taking riociguat or anyone who has had an allergic reaction to the medicine or its ingredients.
Interactions specific to avanafil.
Stendra (avanafil) can interact with some medicines, particularly certain treatments for HIV, fungal infections, heart conditions and antibiotics. Some of these medicines should not be taken with avanafil, while others may require a lower dose or a longer gap between doses.
Before starting treatment, tell your prescriber about all the medicines you take, including those for HIV, fungal infections, heart conditions or blood pressure. Also let them know if you have kidney or liver problems or any other medical conditions.
Cardiovascular history.
Sexual activity places additional demands on the cardiovascular system. If you have a heart condition, your prescriber will assess whether this erectile dysfunction medication or other ED medications are appropriate before prescribing.
Fertility.
Repeated administration of avanafil 100 mg over 26 weeks in healthy volunteers and men with mild erectile dysfunction was not associated with adverse effects on sperm concentration, count, motility or morphology.
Seek urgent medical attention
If an erection lasts longer than four hours, or if you experience sudden vision or hearing loss. Read the patient information leaflet for full side-effects and warning details.
This guide does not provide dosing instructions. Both medicines should be taken exactly as your prescriber has directed, and dose selection is a clinical decision made after assessment.
Cost and Access in the UK
Most men in the UK obtain sildenafil or avanafil through a private prescription, although some people may be eligible for NHS treatment depending on the underlying cause of their erectile dysfunction and NHS prescribing criteria.
Generic sildenafil is usually the least expensive option because it has been available for many years. Generic avanafil is also available, but it is newer to the market and is generally more expensive. Prices vary depending on the strength, pack size and pharmacy.
What to check before ordering treatment
Prices vary between pharmacies for reasons that are not always obvious. Before ordering, it is worth confirming:
- Whether the advertised price is per tablet or per pack, and how many tablets the pack contains.
- Whether the prescription and clinical assessment are included or charged separately.
- Whether delivery is included, and what the cost is for tracked or next-day options.
- Whether the pharmacy is registered with the General Pharmaceutical Council, which you can verify on the GPhC-register.
- Whether an appropriately qualified prescriber reviews your assessment before the medicine is dispensed.
Larger pack sizes usually reduce the per-tablet cost, but there is a sound argument for starting with a smaller quantity until you know how a given medicine works for you.
How the Online Prescription Process Works
- Complete a clinical questionnaire covering your symptoms, medical history, other medications and any cardiovascular history.
- Prescriber review. An independent prescriber assesses whether this ED (Erectile Dysfunction) treatment is appropriate for you, and may decline or request further information as the prescriber reviewing your case.
- Dispensing and delivery by a registered pharmacy, in discreet packaging.
- Follow-up. If the medicine does not suit you, a further review can consider alternatives within the same class.
An online assessment is not a substitute for seeing your GP. Erectile dysfunction (ED) can sometimes be associated with underlying conditions such as cardiovascular disease, diabetes or hormonal issues, and persistent symptoms deserve a proper investigation rather than treatment alone.
