The feeling of an altered state or a mild “high” when you are sick is a common biological phenomenon. This sensation is a complex, coordinated response orchestrated by your immune system and brain working together. The body shifts its priorities to focus all available resources on fighting the infection, a process that causes changes in mood, perception, and cognitive function. This temporary state is a survival mechanism conserved through evolution across many species.
What Does Feeling High Actually Mean
The sensation often described as “feeling high” when ill is better categorized as an altered mental status involving several distinct experiences. One common component is lightheadedness or dizziness, which can result from temporary changes in blood flow and pressure throughout the body. This feeling can make a person feel unsteady or slightly detached from their surroundings.
Another aspect is dissociation, where a person feels mentally detached from their body or their environment seems unreal, sometimes described as feeling foggy. Additionally, a mild form of delirium or fever dreams can occur, involving vivid and sometimes unsettling alterations in reality perception. These combined sensations create the unusual feeling that people often report experiencing during an illness.
How Inflammation Affects the Brain
The primary driver behind this altered state is the body’s inflammatory response, specifically the actions of chemical messengers called cytokines. When an infection occurs, innate immune cells release pro-inflammatory cytokines (such as Interleukin-1 beta, Interleukin-6, and Tumor Necrosis Factor-alpha) to coordinate the immune defense against pathogens. This response triggers a highly organized strategy known as “sickness behavior,” which is mediated in the central nervous system.
These cytokine molecules act as signals that communicate the presence of infection to the brain. Cytokines can signal the brain by crossing the blood-brain barrier or by activating specialized cells and nerves. Once in the brain, these inflammatory signals affect the hypothalamus, a region that controls body temperature and homeostatic functions, leading to fever and fatigue.
Furthermore, cytokines alter the activity of neurotransmitters like serotonin and dopamine, which regulate mood, motivation, and cognitive function. This chemical disruption causes the cognitive impairment, lethargy, loss of appetite, and altered mood that characterize sickness behavior. This is an adaptive, neurologically mediated response that forces the individual to rest and conserve energy for recovery.
Physical Factors That Change Perception
While the chemical signaling of inflammation is the main cause of sickness behavior, several physical factors can amplify or cause similar perceptual changes. Fever, or an elevated body temperature, directly affects brain function and metabolism. When the body’s temperature is significantly raised, neuronal function can be disrupted, which may lead to confusion, difficulty concentrating, and, in cases of very high fever, delirium or hallucinations.
Another significant factor is dehydration and electrolyte imbalance, which are common when fighting an illness. Fluid loss from sweating due to fever, or from vomiting and diarrhea, reduces the overall volume of blood in the body. This reduced blood volume can cause a drop in blood pressure, leading to lightheadedness, dizziness, and cognitive fogginess.
Certain over-the-counter cold and flu medications can also contribute to an altered mental state. Many common remedies contain ingredients like antihistamines or decongestants that have psychoactive side effects, such as drowsiness or disorientation. These pharmacological effects can compound the body’s natural sickness behavior, making the feeling of being “high” more pronounced.
When to Consult a Doctor
While altered sensations are often a normal part of the body’s immune response, specific signs indicate a potentially serious medical issue requiring professional attention. Seek immediate medical care if you experience severe, persistent confusion, disorientation, or difficulty being roused. These symptoms suggest a significant change in brain function beyond typical sickness behavior.
Other red flags include an extremely high fever, generally above 103°F (39.4°C) in adults, a stiff neck, or the inability to keep fluids down due to persistent vomiting. Hallucinations should also prompt a medical consultation if they are severe, persistent, or accompanied by other concerning symptoms.