The SARS-CoV-2 virus, responsible for COVID-19, is known for its respiratory impact, but a growing body of evidence highlights its significant neurological consequences. These effects range from common issues like “brain fog” and fatigue to more severe psychiatric disturbances, including hallucinations. A hallucination is perceiving something that is not actually present, often involving the senses of sight, sound, or smell. Researchers recognize that neurological and psychiatric symptoms following infection are a distinct concern, affecting individuals during the acute phase and persisting for months as part of long COVID. Understanding the mechanisms behind these sensory changes is necessary for providing appropriate support and treatment.
The Spectrum of Post-COVID Sensory Disturbances
Hallucinations reported by COVID-19 patients cover a wide sensory range. Visual and auditory hallucinations are frequently reported, which may include seeing complex scenes or people who are not there, or hearing voices. These experiences can be part of a broader state of acute confusion and altered consciousness known as delirium, particularly in severely ill, hospitalized individuals.
The spectrum also includes tactile hallucinations, such as the sensation of bugs crawling on the skin, and disturbances in the chemical senses. Olfactory (phantom smells) and gustatory (phantom tastes) hallucinations are common post-COVID sensory issues. Patients may report persistently smelling unpleasant odors, such as burnt rubber or sulfur, when no source is present. These sensory alterations can manifest during the acute infection or emerge weeks or months later as part of a persistent post-viral syndrome.
Biological Factors Driving Neurological Symptoms
The sudden onset of hallucinations following a COVID-19 infection is not typically due to the virus directly invading the brain tissue. Instead, current scientific understanding points to an indirect, systemic disruption that affects brain function. A major contributing factor is the massive inflammatory response triggered by the body’s fight against the virus, often referred to as a “cytokine storm.”
This systemic inflammation involves the release of pro-inflammatory signaling molecules like interleukins and tumor necrosis factor-alpha (TNF-α) into the bloodstream. These molecules travel to the central nervous system, causing neuroinflammation. This process disrupts the balance of neurotransmitters and alters the normal electrical signaling pathways in the brain, which may manifest as psychotic symptoms.
The peripheral inflammation can also compromise the integrity of the blood-brain barrier (BBB), which normally acts as a protective filter for the brain. When the BBB becomes more permeable, inflammatory molecules and immune cells can enter the brain, intensifying the neuroinflammatory state. The virus’s ability to bind to the ACE2 receptor, expressed on brain vascular cells, also contributes to this breakdown.
In severe cases of COVID-19, low oxygen levels, or hypoxia, can lead to damage in various brain regions. When the lungs are severely affected, the brain is deprived of adequate oxygen, which impairs neuronal function and contributes to the development of delirium and hallucinations. Other indirect effects also play a part, including the stress of critical illness, prolonged hospital stays, sleep deprivation, and the use of certain medications, such as corticosteroids, which are known to have potential psychiatric side effects.
Identifying Individuals at Higher Risk
The likelihood of experiencing COVID-related hallucinations is not uniform across all infected individuals, with certain factors increasing vulnerability. Advanced age is consistently linked to a higher risk, as older adults are more susceptible to delirium and other neurological complications during acute illness. People with a pre-existing history of neurological or psychiatric conditions, such as a prior diagnosis of psychosis, also appear to be at greater risk of developing or exacerbating psychotic symptoms.
The severity of the COVID-19 infection itself is another strong predictor. Patients who experience a severe course of the disease, requiring admission to an Intensive Care Unit (ICU) or mechanical ventilation, have a significantly higher incidence of delirium that includes hallucinations. Prolonged hospital stays and the associated factors of isolation and sensory deprivation can also contribute to psychological vulnerability. This suggests that the interplay between biological vulnerability and the stressful, inflammatory environment of a severe infection creates the highest-risk scenario.
Managing and Treating COVID-Related Hallucinations
For individuals experiencing new or persistent hallucinations following a COVID-19 infection, the first step is to seek immediate medical consultation with a healthcare provider, ideally a neurologist or psychiatrist. A thorough evaluation is necessary to rule out other medical causes, such as brain tumors, epilepsy, or autoimmune encephalopathy, that may coincidentally present with similar symptoms. This process, known as differential diagnosis, often involves imaging tests like MRI or CT scans and an electroencephalogram (EEG) to measure brain activity.
Management strategies typically involve a combination of supportive care and targeted pharmacological interventions. Supportive care focuses on optimizing the patient’s overall well-being, including improving sleep hygiene, reducing environmental stressors, and ensuring adequate nutrition and hydration. For patients whose hallucinations are part of a broader psychotic episode, low-to-moderate doses of antipsychotic medications, such as risperidone or olanzapine, have proven effective in many cases. Close monitoring and follow-up care are crucial, particularly for those whose symptoms persist as part of long COVID, as the duration of treatment may need to be adjusted based on the patient’s recovery trajectory.