Disadvantage of ketamine is

When administered to adult patients as a sole anaesthetic agent, ketamine frequently causes emergency reaction characterized by anxiety, hallucination, delirium. Moreover, ketamine shows cardiovascular stimulant propey (increases hea rate and BP), increases salivary and bronchial secretions, and may increase intracranial, intraocular and pulmonary pressure. All of these features have been advocated as limitations for its usefulness.(Refer: stoelting's pharmacology and physiology in anaesthetic practice, 5th edition, pg no.294)