Living organisms, particularly human are exposed to chemical substances or toxins at least once during the lifetime and it is not without any consequences. Toxicology studies the relationship between the doses of drugs and its effects on living organisms. It is a study that deals with the symptoms, treatments, detection and mechanism of how to cope with it. It particularly emphasizes the amount of chemical exposure and its consequences. It deals with the study of xenobiotics and alsostudy toxic effects of agents (drugs) whose purpose is to ameliorate or prevent a disease. Clinical toxicology is processes with are involved with the different forms of toxic chemicals and they associated with the different forms of diseases. It typically coincides with other sciences like as biochemistry, pharmacology and pathology. Clinical toxicology deals with the adverse effects of agents such as chemical, drugs etc. Toxicity is a degree from which the substance can get damage. Toxicity can affect the whole organism such as animals, plants, bacteria and humans beings. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Subchronic toxicity is the ability of a toxic substance to cause effects for more than one year but less than the lifetime of the exposed organism. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure, sometimes lasting for the entire life of the exposed organism.