What is confusion? Confusion occurs when a person has difficulty understanding a situation or has disordered or unclear thoughts. It can be accompanied by memory loss, disorientation, or the inability to think quickly. Confusion can increase slowly over time or come on abruptly, depending upon the cause. It may be associated with serious infections, some chronic medical conditions, head injury, brain or spinal cord tumor, delirium, stroke, or dementia. It can also be caused by alcohol or drug intoxication, sleep disorders, chemical or electrolyte imbalances, vitamin deficiencies, or medications. It can also occur in the period following a seizure or as a result of hypothermia. Confusion in the elderly may be aggravated by environment changes, such as being admitted to the hospital, or as a result of sundowning (confusion occurring late in the day or at night, that may accompany certain types of dementia) in the late afternoon or evening. Behavioral changes can accompany confusion. Depending upon the cause, confusion may be a temporary, treatable condition or may be progressive. Seek immediate medical care (call 911)for the rapid onset of confusion, especially if it is accompanied by high fever (higher than 101 degrees Fahrenheit), neck stiffness or rigidity, rash, head injury, changes in level of consciousness or alertness, flushing or dry skin, severe nausea and vomiting, fruity breath, or other symptoms that cause you concern.