what are the side effects of ginseng?!

Although generally well tolerated, caution is advised when consuming ginseng along with over-the-counter or prescription drugs.
According to a Sports Nutrition FAQ published by UMass Amherst, one of P. ginseng's most common side effects is the inability to sleep. However, other sources state ginseng causes no sleep difficulties. Other side effects can include nausea, diarrhea, headaches, epistaxis, high blood pressure, low blood pressure, and mastalgia. Ginseng may also lead to induction of mania in depressed patients who mix it with antidepressants.

Both American ginseng (Panax quinquefolius) and Asian ginseng (Panax ginseng) roots are taken orally as adaptogens, aphrodisiacs, nourishing stimulants, and in the treatment of type II diabetes, as well as for sexual dysfunction in men. The root is most often available in dried form, either whole or sliced. Ginseng leaf, although not as highly prized, is sometimes also used; as with the root, it is most often available in dried form.
This ingredient may also be found in some popular energy drinks, often the "tea" varieties; in these products, ginseng is usually present in subclinical doses and does not have measurable medicinal effects.It can be found in cosmetic preparations as well, but has not been shown to have clinically effective results.

Just anything can make a person addicted to it - depends on person. Generally no but same like drinking - everyone drinks and just a few become addicted.

http://en.wikipedia.org/wiki/Ginseng