Herbal medicines have recently been used for treatment of various diseases. The unwanted reaction and other concern like authenticity of herbal drugs is one of the important issues that have been addressed in this article. Toxicity of various important herbal drugs which are used regularly may also induce fatal reaction in our body. Herbal drug interaction with conventional drug and their serious consequences may be also life threatening for the patients who consume herbal drugs. Drug mutagenicity and contamination of herbal drugs are discussed here with suitable example. Drug authenticity with suitable illustration is also depicted in this review article. The aim of this article is to deliver an insight to the critical points of modern herbal drugs therapy and to find the scope for future scientists to overcome the serious issues regarding the herbal drugs treatment in recent era.