Erectile dysfunction is one of the most common health problems affecting men and becomes more common with increasing age. Fortunately, the condition is treatable at any age and a majority of those seeking treatment are able to return to normal sexual activity.

The three most commonly prescribed oral medications used to treat erectile dysfunction are: Viagra (sildenafil), Levitra (vardenafil), and Cialis (tadalafil). All three medications are phosphodiesterase (PDE) inhibitors and are similar in the way they block the enzyme phosphodiesterase type 5 (PDE-5). The major advantage of these medications for sexual enhancement is that they do no cause an erection at inappropriate times, because they act only in response to sexual stimulation. If there is no sexual stimulation, the drug remains inactive within the body.

If desired results aren’t achieved using one of these options, the others may be tried. However, because these drugs work the same way, it’s unlikely that you’ll have success with one of you’ve failed to achieve an adequate erection with another.

Serious side effects may result from interactions with other medications, or if you are experiencing any other health issues. These drugs are not to be used by men taking any form of nitrates for chest pain, or alpha-blockers for high blood pressure. When taken with those drugs, ED drugs (PDE-5 inhibitors) can cause a sudden and dangerous drop in blood pressure. With all ED drugs, there is also a small risk of priapism, a prolonged erection in which blood fails to drain from the penis.

Like all medical treatments, prescription drugs for the treatment of erectile dysfunction should only be taken under the careful supervision of a physician.





Pfizer/ 1998


Eli Lilly& Co /2003

Available dose

25mg, 50mg, 100mg

2.5mg, 5mg, 10mg, 20mg

2.5mg, 5mg, 10mg, 20mg

Recommended dose








Should be taken

30-60 minutes prior to sexual activity on an empty stomach

25-45 minutes prior to sexual activity

20 minutes – 12 hours prior to sexual activity

Duration of effects

4 to 5 hours

4 to 6 hours

36 hours

Most common side effects

Facial flushing, headache, indigestion, altered vision

Headache, indigestions, facial flushing, back pain

Headache indigestion, back pain, muscle aches

Active Ingredient

Sildenafil Citrate


Vardenafil HCL