I didn't know what it is so I did a search:
"Honestly, so many people post questions on Nolva and it's not as though it's a big secret. Nolvadex is the marketing name for Tamoxifen Citrate which is an estrogen receptor agonist meaning that it is itself an estrogen with very low activity but high affinity for estrogen receptor sites. This means Nolva will not affect circulating estrogen levels directly but will prevent circulating estrogen from reaching receptor sites where it can affect the body. Tamoxifen Citrate aka Nolva IS A DRUG used to treat breast cancer in women but has recieved acceptance in bodybuilding circles for use in PCT and preventing onset of gynomencia.
Nolva is better for preventing the onset of gynomencia and it's a debatable topic as to whether it can treat gynomencia at all. I have not heard of anybody successfully treating gynomencia with Nolva but then again real cases of gynomencia are extremely rare today because most people take adequate preventative measures or limit the use of aromatizing steroids. Having said this most people don't know what real gynomencia is and think any lump beneath their nipple region is benign growth of breast tissue or think saggy man boobs while at 20%+ body fat is gynomencia.
As for treating real gynomencia the only real option is surgery, however minor cases that appear like pecs tapering off to pointed nipples rather than a smoot flat appearence, frequently associated with prohormone or prosteroid use is a different matter. Cases such as the latter sometimes clear up themselves without doing anything so its difficult to tell from anecdotal evidence whether proposed remedies actually work but there have been some reports by people on this board that ATD, the key ingredient in Rebound XT and Ultra H.O.T may reduce gyno in minor cases. This would be the preferred option because ATD is an OTC supplement and all indications show that it's more effective for treating minor cases of gyno than Nolva."http://forum.bodybuilding.com/showthread.php?t=527274&page=1