The relationship between fever and blood pressure is a common question for many experiencing illness. While a fever signals the body is fighting an infection or inflammation, it generally leads to temporary shifts in blood pressure rather than causing sustained hypertension. The body’s response to illness involves various physiological adjustments that can influence blood pressure.
How Fever Affects the Circulatory System
When a fever develops, the hypothalamus, the body’s internal thermostat, raises its set point, initiating physiological changes. This elevation in body temperature increases the metabolic rate, demanding more oxygen and energy. Consequently, heart rate often rises to pump blood more rapidly and deliver necessary resources throughout the body.
This increased cardiac output can lead to temporary fluctuations in blood pressure. The body also adjusts blood vessel diameter; for instance, superficial blood vessels may dilate to help dissipate heat, while other areas might experience slight vasoconstriction. These dynamic changes are part of the body’s natural defense mechanisms and do not typically result in chronic high blood pressure.
Other Factors Influencing Blood Pressure During Illness
Beyond fever’s direct effects, other factors can influence blood pressure during illness. Pain and discomfort from sickness can trigger a stress response, releasing hormones that temporarily increase heart rate and narrow blood vessels, raising blood pressure. Anxiety about the illness or other life stressors can also contribute to these temporary elevations.
Dehydration, common with fever, vomiting, or diarrhea, reduces blood volume, which can cause blood pressure to drop. Certain over-the-counter medications, such as decongestants, can also elevate blood pressure by constricting blood vessels. Individuals with pre-existing conditions, especially hypertension, may find their blood pressure more prone to spikes during illness, highlighting the importance of monitoring in these cases.
When to Be Concerned and Seek Medical Advice
While temporary blood pressure fluctuations during a fever are common, certain signs warrant medical attention. Extremely high readings, especially if consistently 180/120 mm Hg or higher, should prompt immediate medical evaluation. Persistent high blood pressure even after the fever subsides is also concerning and requires professional assessment.
Accompanying symptoms such as chest pain, severe headache, sudden changes in vision, difficulty speaking, or shortness of breath alongside elevated blood pressure are warning signs of a potential medical emergency. During illness, it is advisable to monitor blood pressure, stay well-hydrated, and ensure adequate rest. If any alarming symptoms or sustained high readings occur, seeking prompt medical advice is important.