Cialis vs Viagra: Which One’s Better? (2024)

Learn the difference between Viagra and Cialis to determine which one could be best for you in our ultimate guide to these popular ED medications.

Updated: Wednesday 31 January 2024


viagra-vs-cialis

Viagra and Cialis are two of the most popular medications for erectile dysfunction. Viagra was developed by Pfizer Pharmaceuticals and gained approval for use in the UK in 1998. Following this, Cialis made its debut five years later in 2003.

Over the years, both of these ED treatments have become renowned for their effectiveness and remain popular given the prevalence of ED in the UK.[1] But what is the difference between Viagra and Cialis, and are there any other ED meds and treatments that can help with relieving the associated symptoms?

Continue reading to find out the answers to these questions in this comprehensive guide prepared by our experts.

What is the difference between Viagra and Cialis?

Active ingredients (Tadalafil vs Sildenafil)

Cialis and Viagra have different active ingredients - Cialis pills contain Tadalafil whereas Viagra pills contain Sildenafil. With that said, both Tadalafil and Sildenafil are classified as Phosphodiesterase-5 (PDE-5) inhibitors that cause the arteries supplying blood flow to the penis to relax, resulting in a temporary increase in blood flow and causing an erection following sexual arousal.[2]

Onset of effects

Cialis takes between 15 to 30 minutes before the effects can be felt after ingestion, while Viagra takes between 30 to 60 minutes. This difference is mainly because of how food intake affects the rate of absorption of the active ingredients inside each medication.

The Tadalafil inside Cialis tends to be absorbed into the bloodstream quickly irrespective of whether food has been consumed prior. In comparison, taking Viagra after a heavy or high-fat meal can delay its absorption, leading to a longer time before it becomes effective.[3]

Recommended reading: What to do if your ED medication isn’t working

Duration of effects

One of the biggest differences between Viagra and Cialis is the duration of effects. Viagra typically lasts for 4 hours, while Cialis typically lasts for up to 36 hours. There are two key reasons for this difference:

  1. The half-life of the active ingredient in Cialis (Tadalafil) is 17.5 hours,[4] which is significantly longer than the half-life of the active ingredient in Viagra (Sildenafil). This means that the concentration of Tadalafil in the blood takes 17.5 hours to reduce by half.

  2. The highest concentration of Tadalafil in the blood is generally reached about 2 hours after ingestion irrespective of food intake.[5] In comparison, it can take up to 3 hours to reach the highest concentration of Viagra in the blood if a high-fat meal is consumed before the treatment is taken.[6]

Viagra vs Cialis dosage

Viagra dosage

Viagra is available in three doses:

  • 25 mg (low dose)
  • 50 mg (standard dose)
  • 100 mg (high dose)

Cialis dosage

Cialis is available in the following doses:

  • Cialis On-demand (10 mg and 20 mg) tablets, which last for up to 36 hours where tablets are taken at least half an hour before planned intimacy.
  • Cialis Daily, which has the same active ingredient as Cialis On-demand but at lower strengths of 2.5 mg and 5 mg and is formulated to be taken daily, providing a continuous level of Cialis in the body and allowing you to achieve or maintain an erection at any desired time.

The difference in dosage between Viagra and Cialis is primarily due to the time taken for the onset of effects as well as the duration of effects.


Due to its long-lasting effects, Cialis is effective in lower daily dosages, allowing for continuous treatment of ED. In comparison, Viagra has a shorter duration of action which is why the appropriate dosage must be tailored to match individual needs and health.

Ultimately, the correct dosage of Viagra or Cialis will vary from person to person depending on factors such as their health, frequency of sexual activity, response to ED meds, and more. Therefore, it is imperative to consult a pharmacist or GP before taking any erectile dysfunction medication.

Viagra vs Cialis side effects

Cialis and Viagra produce minimal side effects for the majority of men who take them. Some men may experience mild side effects and less than 1% of those who take them report substantial side effects. The risk of Viagra and Cialis side effects can be minimised by consulting a pharmacist or GP before taking these ED meds.

Some side effects of Viagra and Cialis include:

  • Headaches
  • Facial flushes
  • Dizziness
  • Nasal congestion
  • Indigestion

In addition to the above, Viagra can cause blurred vision and Cialis can cause muscle aches. However, both of these side effects are extremely rare.

Viagra vs Cialis price

Cialis is more expensive than Viagra, however, it is often seen as a more cost-effective option due to its long duration of action. With that said, generic Sildenafil and generic Tadalafil are much cheaper than Viagra and Cialis despite being medically identical to their branded counterparts.

Comparing branded and generic Cialis and Viagra

Sildenafil vs Viagra

Sildenafil (generic Viagra) and Viagra are medically identical, which means there is no chemical difference between the two ED treatments. The only difference is branding and pricing - Sildenafil is cheaper than Viagra as it is generic (unbranded).

Viagra is the brand name originally developed and marketed by Pfizer, while generic Sildenafil is the unbranded version of the same medication. The name "Viagra" is a brand name used to market Sildenafil.

As mentioned previously, Viagra is more expensive than generic Sildenafil because of the brand value associated with it. Generic Sildenafil became available after the patent for Viagra expired, allowing other pharmaceutical companies to produce Sildenafil at a lower price.

Recommended reading: Viagra vs Sildenafil

Tadalafil vs Cialis

Tadalafil and Cialis are medically identical to one another with the only difference being branding and pricing - Tadalafil is cheaper than Cialis as it is generic (unbranded).

Generic Tadalafil became available after the patent for Cialis expired, allowing other pharmaceutical companies to produce Tadalafil at a lower price.

Is Cialis better than Viagra?

Whether Cialis is better for an individual to take than Viagra or vice versa ultimately depends on their preferences for factors like the time taken for the onset of effects, the duration of action, and flexibility with food intake.

For instance, Cialis lasts up to 36 hours, providing a larger window for spontaneous sexual activity, whereas Viagra lasts about 4-6 hours. Moreover, Cialis can produce effects quicker than Viagra as the latter is more likely to be affected by food intake.

Other erectile dysfunction medications and treatments

Viagra Connect

Viagra Connect is an over-the-counter version of Viagra. It contains 50 mg of the same active ingredient as Viagra (Sildenafil) and is a PDE-5 inhibitor that works by increasing blood flow to the penis by relaxing the muscles in the blood vessel walls to help with achieving and maintaining an erection following sexual arousal.

Recommended reading: One Year of Viagra Connect

Cialis Together

Cialis Together is an over-the-counter version of Cialis. It contains 10 mg of the same active ingredient as Cialis (Tadalafil) and also inhibits the PDE-5 enzyme in the body to relax muscles in the blood vessel walls and improve blood flow to the penis following sexual arousal.

Vardenafil

Vardenafil is also a PDE-5 inhibitor, but it has a slightly different molecular structure to other ED treatments, making it more suitable for diabetics.

Spedra (Avanafil)

Spedra is also a PDE-5 inhibitor and contains the active ingredient Avanafil. The molecular structure of Avanafil allows for a quicker onset of effects (as little as 15 minutes) compared to other erectile dysfunction medications.

VaxAid Deluxe

VaxAid Deluxe utilises hydrotherapy to create a seal on the pelvic seat, improving blood flow in the penis using a vacuum pump. In contrast to ED meds, VaxAid Deluxe is a non-oral treatment for erectile dysfunction.

Recommended reading: Which erectile dysfunction treatment is best for me? (2024)

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 Sources 
  1. Li et al. (2022). ‘Prevalence, comorbidities, and risk factors of erectile dysfunction: results from a prospective real-world study in the United Kingdom’, International Journal of Clinical Practice, Article ID 5229702. doi: 10.1155/2022/5229702.
  2. Dhaliwal & Gupta. (2023). PDE-5 Inhibitors. Available at: https://www.ncbi.nlm.nih.gov/books/NBK549843/ [Accessed 30 November 2023].
  3. Mayo Clinic. (2023). Erectile dysfunction: Viagra and other oral medications. Available at: https://www.mayoclinic.org/diseases-conditions/erectile-dysfunction/in-depth/erectile-dysfunction/art-20047821 [Accessed 30 November 2023].
  4. Cui et al. (2014). Efficacy and safety of long-term tadalafil 5 mg once daily combined with sildenafil 50 mg as needed at the early stage of treatment for patients with erectile dysfunction’, Andrologia, 47(1), pp. 20-24. doi: 10.1111/and.12216.
  5. European Medicines Agency. (n.d.). Cialis Product Information. Available at: https://www.ema.europa.eu/en/documents/product-information/cialis-epar-product-information_en.pdf#page=12 [Accessed 30 November 2023].
  6. U.S. Food and Drug Administration. (n.d.). Viagra (sildenafil citrate) tablets. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/020895s027lbl.pdf#page=28 [Accessed 30 November 2023].
Kamran Bell

Written by: Kamran Bell

Pharmacist・GPHC Number 2231070

Kamran graduated with a four-year master's degree in pharmacy from Aston University in 2021. He completed a pre-registration year at a community pharmacy before working there for a further year. At Pharmica, Kamran provides expert patient advice and addresses clinical questions to ensure the health and well-being of our patients.

Carolina Goncalves

Medically Reviewed by: Carolina Goncalves

Superintendent Pharmacist・GPHC Number 2088658

Carolina Goncalves is the Superintendent Pharmacist at Pharmica, where she ensures patients receive exceptional healthcare and support, as part of a seamless online pharmacy service.

With a comprehensive professional background spanning more than 13 years, Carolina has extensive experience supporting Men’s and Women’s health. Carolina is responsible for providing expert treatment advice to thousands of patients in areas such as Sexual Health, Erectile Dysfunction, Hair Loss, Weight Loss and Asthma.

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Erectile Dysfunction: Everything You Need to Know
Erectile Dysfunction: Everything You Need to Know
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