A fever indicates an elevated body temperature, a natural response by the body’s immune system to fight off an infection or illness. Blood pressure measures the force of blood against the walls of your arteries as your heart pumps it. When the body experiences a fever, blood pressure can rise; this increase is typically temporary and represents a normal physiological adjustment. This temporary elevation is part of the body’s defense mechanisms, helping to manage the increased metabolic demands.
How Fever Affects Blood Pressure
The body’s metabolism significantly increases during a fever as it works to combat pathogens, which often leads to an elevated heart rate. A faster heart rate means the heart pumps more blood per minute, increasing the volume of blood in the arteries and raising blood pressure. This metabolic boost helps to circulate immune cells and other defense mechanisms more efficiently.
Initially, the body might try to dissipate heat through vasodilation, where blood vessels widen, which can temporarily cause a slight drop in blood pressure. However, this is usually followed by compensatory mechanisms, such as the increased heart rate, which typically lead to a net increase in blood pressure. If the fever causes shivering or feelings of coldness, the blood vessels can constrict, further influencing blood pressure by increasing resistance to blood flow.
Increased sweating is a common response to fever, which can lead to significant fluid loss and potentially dehydration. Dehydration can cause the blood volume to decrease, which might initially lower blood pressure. However, the body compensates for this reduced volume by increasing the heart rate to maintain adequate blood flow, contributing to a temporary rise in blood pressure.
The stress response triggered by illness also plays a role in blood pressure changes. When the body is under stress, it releases hormones like adrenaline and noradrenaline, which can narrow blood vessels and increase heart rate. These hormonal effects contribute to the temporary elevation in blood pressure during a febrile state.
Important Considerations During Fever
Individuals with pre-existing health conditions, such as chronic hypertension, heart disease, or kidney problems, should pay close attention to blood pressure changes during a fever. Their cardiovascular systems may be less able to adapt to temporary increases in blood pressure, potentially exacerbating their underlying conditions. Consulting a healthcare provider is advisable if they develop a fever.
Monitoring blood pressure at home can be beneficial for some individuals, especially those with known cardiovascular issues. While a temporary rise is common, consistently very high readings (e.g., above 180/120 mmHg) or unusually low readings, particularly if accompanied by symptoms, warrant professional medical evaluation. It is recommended to measure blood pressure after resting for a few minutes.
Certain symptoms or situations indicate a need for immediate medical attention during a fever. These include severe symptoms like confusion, persistent severe headache, difficulty breathing, or chest pain. Signs of severe dehydration, such as reduced urination, extreme thirst, or dizziness upon standing, also require prompt care. Seeking medical advice is prudent if the fever is extremely high (e.g., over 103°F or 39.4°C) or persists for several days without improvement.
General self-care measures can help manage fever symptoms and support the body’s recovery. Maintaining adequate hydration by drinking plenty of fluids like water or clear broths is important to counteract fluid loss from sweating. Getting sufficient rest allows the body to conserve energy and focus on fighting the infection. Over-the-counter fever-reducing medications, if advised by a healthcare professional, can help alleviate discomfort and reduce body temperature.