Is triclosan harmful?
Triclosan (2,4,4′-trichloro-2′-hydroxydiphenyl ether) is a nonionic, broad spectrum, antimicrobial agent that, because of its favorable safety profile, has been incorporated into a variety of many personal care products, including deodorant soaps, underarm deodorants, shower gels, and health care personnel handwashes. Triclosan exhibits a moderate degree of substantivity to the skin, and, in many products, it imparts a remnant antimicrobial effect.Here is the link. 

U.S. Food and Drug Administration (FDA) states that "Triclosan is not currently known to be hazardous to humans."

Despite having significant uses, it also posses little amount of adverse effects on prolong use.It impairs muscle function and skeletal muscle contractile property.This research has only been conducted in mice and results were not good; when mice were exposed to triclosan, heart muscle function was reduced by 25 percent and grip strength was reduced by 18 %.
So result has concluded that it might cause skeletal and heart muscle failure in humans as well.Here is the link.

Exposures to triclosan can also cause dermatitis, or skin irritation, and an increase in allergic reactions, especially in children.Due to its link with dioxin, it has been suspected to cause other health problems like weakening of the immune system, decreased fertility, miscarriage, birth defects, and cancer.Here is the link

But to eradicate these effects,FDA has been engaged in an ongoing scientific and regulatory review of this ingredient. FDA does not have sufficient safety evidence to recommend changing consumer use of products that contain triclosan at this time.

So we can conclude that, it cannot be considered entirely harmful for human body.