Tadalafil vs Viagra: How do they compare?

DoktorABC editorial team

Accurate, up-to-date health information written by our editorial team and reviewed by UK-registered prescribers.

What is tadalafil and how does it relate to Cialis?

Tadalafil is the active ingredient in Cialis, in the same way that sildenafil is the active ingredient in Viagra. Both are available in the UK as branded products (Cialis and Viagra) and as generic versions (tadalafil and sildenafil) at significantly lower prices. Generic versions contain the same active ingredient at the same dose and are subject to identical MHRA regulatory standards.

Both medicines work by inhibiting PDE5, an enzyme that breaks down cyclic GMP (a chemical messenger that relaxes smooth muscle and increases blood flow) in the penile arteries. This enhances the effect of nitric oxide in the presence of sexual stimulation, producing vasodilation and an erection. Neither medicine works without sexual arousal.

The key pharmacological difference is their half-life (the time it takes for the body to reduce drug concentration by half). Sildenafil has a half-life of three to five hours; tadalafil's is approximately 17.5 hours. This is why tadalafil remains active for up to 36 hours and can be taken as a once-daily low dose.

Tadalafil vs Viagra: Key comparison table

Prices based on UK private prescription data, April 2026.

Is tadalafil better than Viagra?

Neither is clinically superior. Both produce comparable rates of successful erections in clinical trials, and neither is recommended over the other in MHRA or NICE guidance for ED. The better choice depends on individual lifestyle and preference.

Tadalafil tends to suit men who prefer not to plan sexual activity around a medication window, who have sex frequently, or who find Viagra's food interaction inconvenient. Sildenafil tends to suit men who prefer occasional on-demand use, a shorter and more defined treatment window, or who are primarily motivated by cost.

Is tadalafil stronger than Viagra?

Not in any straightforward sense. Tadalafil and sildenafil have different molecular structures and different dose-response curves. The fact that tadalafil is effective at 10 to 20 mg while sildenafil requires 25 to 100 mg does not mean tadalafil is stronger; it reflects differences in molecular potency and pharmacokinetics rather than a difference in clinical effect.

Both medicines produce comparable clinical outcomes at their respective recommended doses. There is no clinical evidence that tadalafil produces firmer erections, higher success rates, or a more powerful response than sildenafil. Individual variation in response to each medicine is real and worth discussing with your prescriber, but it does not reflect one medicine being inherently stronger than the other.

Side effect comparison

The side effect profiles of tadalafil and sildenafil are broadly similar, as both are PDE5 inhibitors. The most common effects with both are headache, facial flushing, nasal congestion, and indigestion.

The most clinically notable differences are that back pain and muscle aches are more commonly associated with tadalafil, while visual disturbances (a bluish tinge or increased light sensitivity) are more associated with sildenafil.

Both medicines share the same absolute contraindication: they must never be taken with nitrate medications, as the combination can cause a severe and potentially life-threatening drop in blood pressure.

When is tadalafil the better choice?

Tadalafil is likely to suit you better if:

• You prefer spontaneity and do not want to time a dose around sexual activity
• You have sex more than twice a week, making daily tadalafil more practical than repeated on-demand dosing
• You want to avoid Viagra's food interaction, as tadalafil can be taken with or without food
• You have tried sildenafil and found the four to six-hour window insufficient or inconvenient
• Performance anxiety is a factor and removing the pressure of timing medication would be helpful

When is Viagra (sildenafil) the better choice?

Sildenafil is likely to suit you better if:

• You have sex occasionally and prefer straightforward on-demand use
• You want a shorter, more defined treatment window with no continuous medication in your system
• Cost is a primary consideration, as generic sildenafil is among the most competitively priced ED treatments available in the UK
• You have tried tadalafil and experienced back pain or muscle aches, which are more commonly reported with that medicine

How do you get tadalafil or Viagra in the UK?

Both medicines are prescription-only in the UK and require a clinical assessment by a UK-registered prescriber before they can be issued. A prescriber will review your health history, current medications, and any cardiovascular risk factors before recommending the most appropriate treatment and dose.

Both sildenafil and tadalafil are available on NHS prescription for eligible patients. Speak to your GP about whether you qualify for NHS-funded treatment. For patients who prefer private access, DoktorABC connects UK patients with licensed prescribers who can assess suitability for treatment and provide ongoing clinical guidance.

Final thoughts

Tadalafil and Viagra are both effective, well-evidenced treatments for ED. The decision between them is a practical one based on lifestyle, frequency of sexual activity, food habits, and individual tolerability rather than one being objectively better or stronger than the other. A conversation with your GP or a UK-registered prescriber is the most reliable way to determine which is most appropriate for you.

For a more detailed comparison of the two medicines including pricing, dose equivalence, and spontaneity considerations, see our full Cialis vs Viagra guide.

FAQ

The DoktorABC medical advisory board

Dr. Roland Ruiken

Medical advisor, Norway

Dr. Viktor Simunovic

Medical advisor, Croatia

To the medical advisory board