While fever is a widely recognized response to a viral infection, indicating the body’s immune system is actively fighting pathogens, a less common but significant phenomenon can also occur: a drop in body temperature. This might seem counterintuitive given the body’s usual fever response. However, under certain circumstances, a viral infection can indeed lead to a lower than normal body temperature, a condition that warrants attention.
Understanding Body Temperature Regulation
The human body maintains a stable internal temperature, typically around 98.6°F (37°C), through a process called thermoregulation. This precise control is managed primarily by a small region in the brain known as the hypothalamus, often referred to as the body’s thermostat. The hypothalamus constantly receives signals from temperature sensors throughout the body, including the skin and internal organs.
When the body senses it is too cold, the hypothalamus initiates responses to generate and conserve heat. These responses include shivering, which produces heat through muscle contractions, and vasoconstriction, where blood vessels near the skin narrow to reduce heat loss. Conversely, if the body becomes too warm, the hypothalamus triggers mechanisms like sweating, which cools the body as moisture evaporates from the skin, and vasodilation, where blood vessels widen to release heat. A healthy adult’s normal oral temperature can range from 97°F (36.1°C) to 99°F (37.2°C), with slight variations depending on factors like age, activity, and time of day.
Viral Infections and the Body’s Temperature Response
Upon encountering a viral infection, the body’s immune system typically mounts a robust defense, often resulting in a fever. This occurs when immune cells release substances called pyrogens, which can originate from the virus itself or from the body’s own immune response. These pyrogens travel to the hypothalamus and effectively reset its temperature set point to a higher level.
The elevated temperature created by a fever is a protective mechanism, as it can make the body a less favorable environment for viral replication and can enhance the efficiency of immune cells. While fever is a common and usually beneficial sign of the body fighting off infection, it is also possible for a viral infection to lead to a lower than normal body temperature.
Mechanisms Behind Low Body Temperature During Viral Infection
Physiological mechanisms can contribute to a low body temperature during a viral infection. One factor is an overwhelming immune response, particularly in severe infections like sepsis. In such cases, the immune system’s release of inflammatory chemicals, known as cytokines, can become dysregulated, leading to a profound impact on the hypothalamus and causing a temperature drop rather than a rise. This severe inflammatory state can disrupt the body’s normal thermoregulatory control.
Metabolic exhaustion can also play a role, especially in vulnerable individuals. Fighting off a viral infection requires significant energy expenditure, which can lead to metabolic slowdown. When the body’s energy reserves are depleted, its ability to produce sufficient heat can be compromised, resulting in a lower core temperature.
Viral infections can sometimes affect the autonomic nervous system, which regulates involuntary bodily functions, including temperature control. If this system becomes dysfunctional, the body’s ability to manage heat production and loss can be impaired. In some severe viral illnesses, dehydration and malnutrition can also contribute. Reduced fluid intake and poor appetite can further lower the metabolic rate and impact the body’s capacity to maintain warmth.
Recognizing and Responding to Low Body Temperature
Recognizing the signs of low body temperature, or hypothermia, during a viral infection is important. Symptoms can include shivering, which may stop as the temperature continues to drop, along with confusion, slurred speech, and lethargy. The skin may feel cold, breathing might become slow and shallow, and the pulse could be weak. In infants, signs can include bright red, cold skin and lack of energy.
If someone experiences persistent or significantly low body temperature during an infection, seek medical attention promptly. While awaiting professional help, actions can be taken to warm the individual:
- Gently move the person to a warmer, dry place.
- Remove any wet clothing.
- Wrap them in warm blankets or dry coats.
- Offer warm, non-alcoholic, sweet drinks, if the person is conscious.