Side effect? No, it's an effect. It's an amino acid, it's not "meant" for anything. It has a plethora of functions. NOS is marketed towards bodybuilding. I'll copy and paste from wiki:
Function
Arginine plays an important role in cell division, the healing of wounds, removing ammonia from the body, immune function, and the release of hormones.[citation needed] Arginine, taken in combination with proanthocyanidins[4] or yohimbine[5], has also been used as a treatment for erectile dysfunction.
The benefits and functions attributed to oral ingestion of L-arginine include:
* Precursor for the synthesis of nitric oxide (NO)
* Stimulation of the release of growth hormone.
* Improves immune function
* Reduces healing time of injuries (particularly bone)
* Quickens repair time of damaged tissue
* Reduces risk of heart disease
* Increases muscle mass
* Reduces adipose tissue body fat
* Helps improve insulin sensitivity
* Helps decrease blood pressure
* Alleviates male infertility, improving sperm production and motility
* Increases blood circulation throughout the body, including the sex organs
* Improves reproductive ability
[edit] In proteins
The distributing basics of the moderate structure found in geometry, charge distribution and ability to form multiple H-bonds make arginine ideal for binding negatively charged groups. For this reason arginine prefers to be on the outside of the proteins where it can interact with the polar environment. Incorporated in proteins, arginine can also be converted to citrulline by PAD enzymes. In addition, arginine can be methylated by protein methyltransferases.
[edit] As a precursor
Arginine is the immediate precursor of NO, urea, ornithine and agmatine; is necessary for the synthesis of creatine; and can also be used for the synthesis of polyamines (mainly through ornithine and to a lesser degree through agmatine), citrulline, and glutamate. For being a precursor of NO, (relaxes blood vessels), arginine is used in many conditions where vasodilation is required. The presence of asymmetric dimethylarginine (ADMA), a close relative, inhibits the nitric oxide reaction; therefore, ADMA is considered a marker for vascular disease, just as L-arginine is considered a sign of a healthy endothelium.
[edit] Treatment of herpes simplex virus
A low ratio of arginine to lysine may be of benefit in the treatment of herpes simplex virus. For more information, refer to Herpes - Treatment.
[edit] Possible increases in risk of death from heart disease
A clinical trial found that patients taking an L-arginine supplement following a heart attack didn't improve in their vascular tone or their hearts' ability to pump. In fact, more patients who were taking L-arginine died than those taking a placebo and the study was stopped early with the recommendation the supplement not be used by heart attack patients. [6][7][8] The supplement is still widely marketed.
[edit] Lung inflammation and asthma
The Mayo Clinic web page on L-arginine reports that inhalation of L-arginine can increase lung inflammation and worsen asthma.[9]
[edit] Growth hormone
Arginine increases the production of growth hormone.[10]
Submissive or Dominant?