There are other erection drugs a lot like Viagra, such as Cialis (aka tadalafil) and Levitra (aka vardenafil). ‘Generic Viagra’ is an almost identical version of the drug but it’s not sold under these well known brand names. 

One well known generic version is Kamagra. The information here is true for both Viagra and the other types of erection drugs.

The pills work by increasing the flow of blood to the dick, giving harder, longer lasting hard-ons. Effects last around four hours. Cialis tends to last longer (up to one or two days for some men).

• Viagra offers a quick fix for many men with erection problems, whether the cause is physical or more in the mind. 
  

• Men with no real problems getting hard use these drugs too, to boost their sexual performance, especially if on chems that make getting hard-ons difficult.

But there is a flip side:

• Side effects can be a blocked nose, headache, a red face and chest, upset stomach or short-lived slight changes in vision
  

• They’re less likely to work if you’re anxious or your hard-on difficulties have a physical cause (diabetes, circulation or prostate problems).
  

• Rare side effects include blindness, stroke, heart attack or death. But this is usually in men who are older and/or have existing health problems, especially if they’re already on nitrate-based drugs for a heart condition.