Udenafil, a phosphodiesterase type 5 (PDE5) inhibitor, is the active ingredient in Zudena pills, which are used to treat erectile dysfunction (ED) in men.  Udenafil helps men get and keep a hard erection by increasing blood flow to the penis during sexual stimulation.  Although Zudena comes in a variety of strengths, one of the most often prescribed dosages is 100 mg.

Compared to some other ED drugs, Zudena usually starts to act 30 to 60 minutes after administration and can continue to be effective for 12 to 24 hours.  It should not be taken more than once in a 24-hour period and is often used as needed, before to planned sexual activity.

Headache, flushing of the face, congestion of the nose, lightheadedness, and occasionally indigestion are common adverse effects.  Although these side effects are often moderate and transient, they can occasionally become more serious and necessitate prompt medical attention, such as visual problems or prolonged erections (priapism).

Men who use nitrates or certain drugs for heart issues should avoid Zudena since it might cause hazardous decreases in blood pressure.  Before using Zudena, it's crucial to speak with your doctor to make sure it's safe for you, particularly if you have underlying medical conditions or are on other medications.