Hallucinations are the perception of something that doesn’t exist. They can be auditory (heard), visual (seen), tactile (felt) or olfactory (smelled).

These hallucinations can have many causes. The most common causes are recreational drugs and dementia or delirium. But they can also be caused by high fevers or certain illnesses. Some people who have survived serious, life-threatening illnesses, like septic shock, report having very vivid hallucinations while they were in the intensive care unit (ICU).

Hallucinations are often very disturbing and the memories can last, but scientists don’t understand them. A few researchers are looking at how often hallucinations occur among critically ill patients. One study looked at 289 critically ill patients who had been in an ICU for 24 hours or longer and been sedated and intubated (placed on a ventilator). The researchers found that 9.3% of the patient had nightmares and 6.6% said that they had experienced hallucinations. For some people, the hallucinations continue, even after they are no longer in the ICU environment. Another study found that after leaving the critical care area, some patients experienced, “amnesia, continued hallucinations or flashbacks, anxiety, depression, and dreams and nightmares.”

No clear cause for hallucinations

There are theories as to why patients may experience hallucinations, but there are no clear explanations yet. Patients in an ICU are not only fighting a very serious illness, they don’t get a lot of rest. Nursing care is necessary and frequent, and lights are on in the hallways. Even with dimmed lights, patients might not be able to sleep. There is a lot of noise that comes from nurses moving about and talking, machines operating, and alarms beeping. The constant stimulation often causes sleep deprivation. Serious lack of sleep can cause psychological distress.

If you experienced hallucinations while hospitalized for sepsis or septic shock, you are not alone. Some of the people who have shared their stories in our Faces of Sepsis section mention that they saw or heard things that they knew weren’t there.

Getting help

If you are having a hard time dealing with the after effects of sepsis, which can include bad dreams, hallucinations, even memories of the hallucinations, this could be part of post-traumatic stress disorder, or PTSD. There are counselors and therapists who specialize in treating PTSD. They may use a variety of methods, including cognitive therapy, tapping techniques, or eye movement desensitization reprocessing (EMDR). Counseling can be an important component of full recovery from sepsis.

Hallucinations are also a change in mental status. This could be a sign of sepsis.

If you suspect sepsis, call 9-1-1 or go to a hospital and tell your medical professional, “I AM CONCERNED ABOUT SEPSIS.” 

Would you like to share your story about sepsis or read about others who have had sepsis? Please visit Faces of Sepsis, where you will find hundreds of stories from survivors and tributes to those who died from sepsis.

Updated November 1, 2021.