What effects does it have?

What is it?

Medication that chemically assists erections of the penis.

It's also known as Viagra.

How long does it last?

Sildenafil takes around half an hour to take effect, and the effects may last for several hours.

More information

Alternatives to sildenafil include tadalafil and vardenafil.

While tadalafil does have a longer lasting action than sildenafil and vardenfil, there is no evidence that any of the treatments is more effective than the others 1.

There is good medical evidence that all three treatments are safe 2, with the vast majority of side effects being minor (flushing, headaches, temporary back pain) and subsiding within a few weeks of treatment 3.

You can read more about erectile dysfunction treatments on the NHS Choices website.


  1. 1 Hatzimouratidis, Konstantinos and Hatzichristou, Dimitrios G (2005) “A comparative review of the options for treatment of erectile dysfunction.” Drugs, 65(12), pp. 1621–1650.
  2. 2 Porst, Hartmut, Burnett, Arthur, Brock, Gerald, Ghanem, Hussein, et al. (2013) “SOP conservative (medical and mechanical) treatment of erectile dysfunction.” The journal of sexual medicine, 10(1), pp. 130–171.
  3. 3 Carson, Culley C and Lue, Tom F (2005) “Phosphodiesterase type 5 inhibitors for erectile dysfunction.” BJU international, 96(3), pp. 257–280.

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Page last updated: July 2018