Viagra, Cialis and Spedra: a complete comparison guide
- Compare all three medicines side by side
- The onset differences: What the SmPCs say and what it means in practice
- Duration and spontaneity
- Food and alcohol effects
- Side effect profiles compared
- Who might be best suited to the different treatment options
- Cost and NHS availability
- How to switch between treatments safely
How Viagra, Cialis and Spedra compare
The three medicines share the same mechanism of action but differ across several dimensions that matter in practice. The table below sets out the key features of each, drawn from the current UK SmPCs, to give a clear basis for comparison before the sections that follow go into each area in more detail.
| Feature | Viagra / Viagra Connect (Sildenafil) | Cialis / Cialis Together (Tadalafil) | Spedra (Avanafil) |
|---|---|---|---|
| Active ingredient | Sildenafil citrate | Tadalafil | Avanafil |
| UK brand names | Viagra (POM), Viagra Connect (P) | Cialis (POM), Cialis Together (P) | Spedra (POM only) |
| Licensed doses | 25 mg, 50 mg, 100 mg (POM); 50 mg only (P) | 2.5 mg, 5 mg, 10 mg, 20 mg (POM); 10 mg only (P) | 50 mg, 100 mg, 200 mg (POM only) |
| Typical licensed starting dose | 50 mg | 10 mg on-demand; 2.5–5 mg daily | 100 mg |
| Take before sex | About 1 hour | About 30 minutes (on-demand); daily (low dose) | 15–30 minutes |
| Duration of effect | Up to 4–5 hours | Up to 36 hours | Up to 6–12 hours |
| Food effect | High-fat meal delays onset ~60 min, reduces peak by 29% | No significant food effect | High-fat meal delays onset ~75 min, reduces peak by 39% |
| Alcohol effect | Excessive alcohol may impair erections | Excessive alcohol may impair erections | Alcohol increases risk of hypotension |
| Common side effects | Headache, flushing, nasal congestion, dyspepsia, visual disturbance | Headache, dyspepsia, back pain, myalgia, nasal congestion, flushing | Headache, flushing, nasal congestion, back pain |
| Legal status | Viagra: POM. Viagra Connect: pharmacy medicine (P) | Cialis: POM. Cialis Together: pharmacy medicine (P) | POM only |
| Generic available in UK | Yes (generic sildenafil, widely available) | Yes (generic tadalafil) | No |
| Daily dosing option | No | Yes (2.5 mg or 5 mg) | No |
| NHS availability | Generic sildenafil: unrestricted prescribing. Branded Viagra: restricted | Generic tadalafil: restricted. Branded Cialis: restricted | Restricted |
Sources: Viagra Connect 50 mg SmPC; Cialis Together 10 mg SmPC; Spedra 100 mg SmPC; NICE ESNM45
Onset: what the SmPCs say
Onset is one of the most practically important differences between these three medicines, and also one of the most commonly misunderstood. Let’s break down each medication and how the onset differs.
What onset means in practice: Onset describes when a proportion of men who, on an empty stomach, began to achieve erections of sufficient rigidity for intercourse. It does not mean every man will respond within that window, and real-world onset depends on individual response, the presence of food, and the degree of sexual stimulation.
Viagra / Viagra Connect (Sildenafil): The SmPC recommends taking approximately one hour before sexual activity. In studies where patients had an empty stomach, the median time to onset of erections of sufficient rigidity was 25 minutes, with a range of 12 to 37 minutes.
Cialis / Cialis Together (Tadalafil): The Cialis Together SmPC recommends taking at least 30 minutes before anticipated sexual activity. Clinical studies demonstrated the ability to achieve successful intercourse as early as 30 minutes following 10 mg dosing.
Spedra (Avanafil): The Spedra SmPC states the recommended dose of 100 mg should be taken approximately 15 to 30 minutes before sexual activity. In a clinical study specifically designed to assess onset, avanafil 200 mg produced erections sufficient for penetration in some men as early as 20 minutes after dosing. At approximately 15 minutes after dosing, successful intercourse was achieved in 24.7% of attempts for the 100 mg dose and 28.2% for the 200 mg dose, compared with 13.8% for placebo.
Good to know
NICE ESNM45 notes that according to the SmPCs at the time of its publication, sildenafil should be taken one hour before sexual activity, whereas avanafil and tadalafil should be taken 25 to 30 minutes before. The current Spedra SmPC now states 15 to 30 minutes for the 100 mg and 200 mg doses. Always follow the instructions in the PIL supplied with your specific medicine.
Duration and spontaneity
Duration of effect is one of the most clinically meaningful practical differences between these three medicines.
Viagra / Viagra Connect (Sildenafil) is effective for up to four to five hours after dosing. This requires relatively precise timing around sexual activity, particularly as food can further delay the onset.
Cialis / Cialis Together (Tadalafil) is effective for up to 36 hours in on-demand dosing, and continuously when taken as a daily low dose. The 36-hour window is the most consistently reported practical advantage of tadalafil over the other PDE5 inhibitors: it allows sexual activity to occur naturally within a broad window without the need for precise timing. The daily 5 mg or 2.5 mg dose removes the need for any planning around dosing.
Spedra (Avanafil) has a duration of effect of up to six to 12 hours based on its half-life of approximately six to 17 hours, which is intermediate between sildenafil and tadalafil. Its most distinctive feature is the faster onset rather than duration.
For men for whom spontaneity is the primary consideration, tadalafil on-demand or daily tadalafil offers the greatest flexibility. Avanafil offers a faster onset than sildenafil with less time pressure around administration, but a shorter window than tadalafil.
Food and alcohol effects
Food and alcohol can meaningfully affect how well ED medicines work, and the three treatments differ considerably in how sensitive they are to both. Understanding this is important, particularly if you regularly take the medicine around mealtimes or social occasions.
Viagra / Viagra Connect (Sildenafil): A high-fat meal delays the time to maximum effect by approximately 60 minutes and reduces peak concentration by 29%. Avoiding a large fatty meal before taking sildenafil is practically important for reliable onset.
Cialis / Cialis Together (Tadalafil): Food does not significantly affect the rate or extent of absorption. Cialis Together can be taken with or without food. This is a practical advantage for men whose sexual activity often follows a meal.
Spedra (Avanafil): A high-fat meal delays the onset by approximately 75 minutes and reduces peak concentration by 39%, a more pronounced food effect than sildenafil. The SmPC recommends that onset of activity may be delayed if taken with food. Men who want to take advantage of avanafil’s faster onset are best advised to take it on an empty stomach or after a light meal.
Alcohol: All three medicines advise against excessive alcohol before sexual activity. The SmPC for avanafil makes a specific pharmacological note: combination with alcohol can increase the potential for symptomatic hypotension. All three SmPCs note that excessive alcohol independently impairs erectile function.
Side effect profiles compared
All three medicines share a broadly similar class-level side effect profile, as expected for PDE5 inhibitors. The most commonly reported effects across all three are headache, flushing, and nasal congestion.
| Side effect | Viagra / Viagra Connect (Sildenafil) | Cialis / Cialis Together (Tadalafil) | Spedra (Avanafil) |
|---|---|---|---|
| Headache | Very common (≥1 in 10) | Common (≥1 in 100) | Common (≥1 in 100) |
| Flushing | Common | Common | Common |
| Nasal congestion | Common | Common | Common |
| Dyspepsia / indigestion | Common | Common | Uncommon |
| Back pain | Not specifically listed as common | Common | Uncommon |
| Myalgia | Uncommon | Common | Uncommon |
| Visual disturbance / colour changes | Common | Uncommon | Uncommon (blurred vision) |
| Dizziness | Common | Uncommon | Uncommon |
Notable differences between the profiles:
Visual disturbances are more commonly associated with Viagra, reflecting its relatively lower selectivity for PDE5 over PDE6 compared to Cialis together and Spedra. The visual colour change (blue-green tinge) reported with Viagra is a well-documented class effect at higher doses. Avanafil has approximately 100-fold selectivity for PDE5 over PDE6, which is higher than sildenafil and may explain its lower rate of visual side effects in trials.
Back pain and myalgia are more specifically associated with Cialis than with the other two medicines. They are listed as common in the Cialis Together SmPC and are thought to be related to tadalafil’s inhibition of PDE11, which is present in muscle tissue.
Dyspepsia is more commonly reported with Viagra and Cialis than with Spedra, where it is listed as uncommon rather than common.
An important limitation on comparison: NICE ESNM45 notes explicitly that it is not known how the efficacy, tolerability, and safety of Spedra compared with the other PDE5 inhibitors, as there are no direct head-to-head comparisons and indirect comparisons are limited by differences in study design, populations, and outcome definitions. The side effect frequency comparisons above are drawn from separate SmPCs and should be interpreted with that limitation in mind.
Important !
Stop taking any PDE5 inhibitor and seek immediate medical attention if you experience sudden vision loss or sudden hearing loss. These are rare but serious effects associated with the class. Report any suspected side effects to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.
Who might prefer which medicine
These are practical considerations for discussion with a prescriber, not recommendations. Individual suitability is always confirmed through a clinical assessment.
Viagra / Viagra Connect (Sildenafil) may suit men who:
- Want a widely available and well-established treatment with a long track record
- Are happy to plan around a one-hour pre-dose window
- Prefer a lower cost per tablet via generic prescription
- Want the option of pharmacy access without a GP (Viagra Connect at 50 mg)
Cialis / Cialis Together (Tadalafil) may suit men who:
- Want the greatest flexibility around timing, particularly the 36-hour on-demand window
- Have sex more than once or twice a week and would benefit from daily low-dose dosing
- Take other medication after meals and need a medicine unaffected by food
- Want the option of pharmacy access without a GP (Cialis Together at 10 mg)
- Have a significant psychological component to their ED and benefit from removing performance timing pressure
Spedra (Avanafil) may suit men who:
- Want the fastest possible onset
- Have experienced significant visual side effects with sildenafil
- Find the timing window of sildenafil inconvenient but do not want a 36-hour duration
Good to know
European clinical guidelines advise that the choice of PDE5 inhibitor depends on the frequency of intercourse and the man’s personal experience of these medicines. Men who have tried one PDE5 inhibitor and found it unsatisfactory, whether through lack of effect, side effects, or practical inconvenience, may find a different option within the class suits them better.
Cost and NHS availability
Cost and access vary considerably between the three medicines, and for many men these are as important as the clinical differences. Generic availability, NHS prescribing rules, and whether a prescription is needed at all each play a role in what is practically accessible.
Generic sildenafil (Viagra) is the most cost-effective option and is the only PDE5 inhibitor that can be prescribed on the NHS without restriction for men with erectile dysfunction. Generic sildenafil is available at a significantly lower cost per tablet than any branded option or the other PDE5 inhibitors.
Generic tadalafil (Cialis/ Cialis Together) is also available on prescription but NHS prescribing is restricted to specific patient groups under the same criteria that apply to branded tadalafil.
Generic Avanafil (Spedra) is currently available on the NHS only under restricted circumstances. At the time of the NICE ESNM45 publication, avanafil cost significantly more than generic sildenafil when starting doses were compared. Private prescribing is available through a registered prescriber.
Pharmacy access without a prescription (P medicines):
- Viagra Connect 50 mg and Cialis Together 10 mg are both pharmacy medicines available following a pharmacist consultation, without a GP appointment or prescription.
- Spedra has no pharmacy medicine equivalent and remains prescription-only at all doses.
Switching between treatments safely
If a PDE5 inhibitor has not worked as expected, or has caused side effects that make it difficult to continue, switching to a different option within the class is clinically reasonable. However, switching should always be done under prescriber guidance, for the following reasons:
- The appropriate starting dose of the new medicine needs to be confirmed individually.
- If one PDE5 inhibitor has not worked, it is worth establishing whether the reason was incorrect use (wrong timing, food effect, insufficient stimulation) before attributing it to the medicine itself.
- PDE5 inhibitors must never be combined. The SmPCs for all three medicines state that the safety and efficacy of combining PDE5 inhibitors with other treatments for erectile dysfunction, including other PDE5 inhibitors, have not been studied, and their use in combination is not recommended.
- If Spedra has not worked after an appropriate trial, it is not currently known whether switching to sildenafil or tadalafil would be effective, as men whose ED does not respond to one PDE5 inhibitor were excluded from the avanafil clinical trials.
Conclusion
Viagra/ Viagra Connect, Cialis/ Cialis Together, and Spedra are all effective PDE5 inhibitors with established evidence bases in clinical trials. The differences between them are clinically real but largely practical rather than efficacy-based: onset speed, duration of effect, the presence or absence of food restrictions, specific side effect patterns, cost, and the availability or otherwise of a pharmacy medicine option.
No direct head-to-head comparison across all three medicines has been published. Choosing between them on the basis of indirect comparisons alone is inherently uncertain, which makes the prescriber conversation the most important step. A clinician who understands your lifestyle, health history, and previous experience with ED treatment is better placed to make that recommendation than any comparison article.
FAQ
Is Viagra, Cialis, or Spedra most effective?
There are no published direct head-to-head trials comparing all three medicines. NICE ESNM45 notes explicitly that it is not known how avanafil compares to other PDE5 inhibitors in terms of efficacy and tolerability. All three have demonstrated statistically significant improvement over placebo in clinical trials. The most appropriate choice for any individual depends on their circumstances and should be discussed with a prescriber.
Which works fastest?
Spedra has the fastest documented onset. The Spedra SmPC recommends taking it 15 to 30 minutes before sexual activity at the 100 mg and 200 mg doses, and clinical data showed successful intercourse in some men from 15 minutes post-dose. Cialis and Viagra are recommended 30 minutes and one hour before sexual activity respectively, though individual response varies for all three.
Which lasts longest?
Tadalafil has the longest duration of effect at up to 36 hours for on-demand dosing, and continuously for daily low-dose dosing. Avanafil has an intermediate duration of up to six to 12 hours. Sildenafil lasts up to four to five hours.
Can I take two of these medicines together?
No. Combining PDE5 inhibitors is not recommended and has not been studied for safety or efficacy.
Can I get any of these without a prescription?
Viagra Connect (sildenafil 50 mg) and Cialis Together (tadalafil 10 mg) are pharmacy medicines available following a pharmacist consultation, without a GP appointment. Spedra (avanafil) is prescription-only at all doses and cannot be accessed without a prescriber assessment.
Does food affect all three the same way?
No. Cialis is the least affected by food and can be taken with or without a meal. Viagra’s onset is delayed by approximately 60 minutes by a high-fat meal. Spedra is most affected, with a delay of approximately 75 minutes and a greater reduction in peak concentration from a high-fat meal. For the fastest possible onset, Spedra is best taken on an empty stomach or well away from a large meal.
Is Spedra available on the NHS?
Spedra is available on the NHS only under restricted circumstances. Generic sildenafil is the only PDE5 inhibitor that can be prescribed on the NHS without restriction for men with ED. Speak to your GP about what is available for your specific circumstances.
The DoktorABC medical advisory board
Dr. Roland Ruiken
Medical advisor, Norway
Dr. Viktor Simunovic
Medical advisor, Croatia