Drugs like Viagra, Cialis or Levitra, are the first-line treatment for erectile dysfunction after addressing and correcting medical conditions that contribute to ED with lifestyle changes like diet and exercise. Among the three commercially available PDEIs, analysis shows comparable efficacy. Randomized, controlled studies have shown small, but noteworthy differences among the three drugs.  

Patients who have erectile dysfunction secondary to radical prostatectomy, diabetes mellitus or severe peripheral vascular, have a lower response rate than those with no previous health issues. Diseases that contribute to injury or compromise of the blood supply may be responsible for the lack of success in patients who suffer from them.

Although these drugs have similar efficacy, urologists may need to tailor treatment regimen based on 1) patient’s preference for a particular drug 2) cost of treatment 3) duration of action 4) desired frequency for sexual intercourse 5) adverse-effect profile 6) patient perception. Below is a comparison of these three commonly used agents:
 

Viagra (sildenafil)

• Onset of action: 30 mins
• Duration of action: 4-6 hours
• High fatty meals reduced serum concentration by 29% and increases time to reach maximum serum concentration by 1 hour
• Initial recommended dose: 50mg
• Side effects: headache, flushing, sensitivity to light, upset stomach, runny nose, abnormal vision

Levitra (vardenafil)

• Onset of action: 30mins
• Duration: 4-6 hrs. (on average a little longer than Viagra!)

• High fatty meals reduced serum concentration by 18% and increases time to reach maximum serum concentration by 1 hour
• Initial recommended dose: 10mg

Cialis (tadalafil)

• Onset of action: ½-2 hrs (fastest of all three)
• Duration: 36 hrs (longest of the three)
• Initial recommended dose: 10 mg
• Absorption NOT affected by eating fatty foods
• Side effects: headache, dyspepsia, back pain, rhinitis
  
  

What are the differences among Viagra, Levitra and Cialis?

These drugs all belong to a class of medication known as phosphodiesterase inhibitors (PDEIs) and work by the same mechanism. Choosing one drug over the other depends on their onset of action, duration, contraindications and other individualized preferences. However, because they are similar, if you are unable to see results with one, it is unlikely that another in the same class would work.

What side effects should I be aware of before starting these medications?

Just like all drugs, there are side effects when using PDEIs. Deciding which ones are more tolerable is a matter of choice. Specific side effects are associated with certain drugs, for example; Cialis is commonly associated with back pain, and Viagra with light sensitivity.