US-licensed healthcare providers
Free 2-day shipping
Genuine, FDA-approved treatments
Disclaimer: The information provided on this page is not a substitute for professional medical advice, diagnosis, or treatment. If you have any questions or concerns about your health, please talk to a healthcare provider.
Sildenafil should be taken without food 30-60 minutes before sex and lasts up to 6-8 hours.
Serious side effects include an erection lasting more than 4 hours, sudden vision loss in one or both eyes, and sudden hearing decrease or loss. If these occur, seek medical attention immediately.
Talk to your provider about your medical conditions and medications before taking sildenafil.
Do not take sildenafil if you are allergic to its ingredients or if you are already taking nitrates (such as nitroglycerin), street drugs called “poppers” (such as amyl nitrate, amyl nitrite, butyl nitrate), or guanylate cyclase stimulators (such as riociguat).
How does sildenafil citrate work?
In order to understand how sildenafil citrate works to treat ED, it’s important to first understand the basics of how erections work.
cGMP causes the corpora cavernosa to relax, allowing blood to rush into the cavernosal arteries.
While blood rushes into the penis, the veins that drain blood from the penis get compressed causing the increased blood to be trapped in the penis causing an erection.
An enzyme called phosphodiesterase-5 breaks down cGMP leading the penis to return to its flaccid state.
PDE5 inhibitors (PDE5i), like sildenafil citrate, block this enzyme, leading to higher levels of cGMP and improving the ability to obtain and maintain an erection.
Important safety information
What you should know before taking sildenafil.