Hello, Thanks for writing to Healthcare Magic. I do understand your concerns. Flomax is mostly used as a first line drug for benign prostatitic hyperplasia. The most commonly encountered side effect of this drug is dizziness. This is because the drug binds to the receptors called alpha 1. These are the same receptors present in blood vessels as well. When this drug binds and blocks the blood vessel receptors it decreases the blood pressure leading to dizziness. Moving on to your question, there is another drug called Finasteride. This drug decreases testosterone level. So the major drawback will be decreased size of the testicle in due course of time. If Flomax is not tolerated well he can even opt for surgical intervention such as TURP that are done Trans urethrally.