Your pulse, or heart rate, measures how many times your heart beats in one minute and is a fundamental sign of your body’s state. When you are feeling unwell, it is common to notice this rate has increased, a condition medically known as tachycardia. This elevation results from your body engaging its defenses to fight off infection or manage illness. Understanding this automatic response helps clarify why your heart is working harder and when this natural increase requires medical attention.
The Physiological Reason for Pulse Elevation
The immune response to illness dramatically increases the body’s demand for energy and resources. A significant factor driving an elevated pulse is fever, which increases the core body temperature. For every rise of one degree Fahrenheit, the heart rate accelerates by about ten beats per minute to manage heat and circulate blood more effectively.
The rise in temperature also accelerates the body’s metabolic rate, causing cells to consume oxygen and generate waste products faster. To meet this heightened demand, the heart must pump blood, which carries oxygen and nutrients, more rapidly. The presence of an invader also triggers the sympathetic nervous system, the body’s “fight-or-flight” mechanism. This system releases stress hormones, such as epinephrine and norepinephrine, which stimulate the heart muscle to beat faster.
Dehydration, a common side effect of illness from sweating or fluid loss (vomiting and diarrhea), is another cause of a faster pulse. When the body loses fluid, the total volume of blood circulating decreases. The heart compensates for this lower blood volume by increasing its rate to maintain sufficient blood pressure and ensure oxygen delivery. Furthermore, inflammation caused by the immune system releasing inflammatory markers, like cytokines, can directly signal the heart to increase its pace.
Recognizing Concerning Increases in Heart Rate
While an elevated heart rate is a standard response to illness, a pulse that is excessively high or remains elevated long after a fever breaks can signal a complication. For most adults, a resting heart rate consistently above 100 beats per minute is considered tachycardia. A rate that remains over 120 beats per minute, especially at rest, warrants evaluation by a healthcare professional.
Symptoms accompanying a fast pulse are often more telling than the number alone and should prompt immediate medical attention. These warning signs include chest pain or discomfort, or a sudden feeling of shortness of breath. It is also concerning if the rapid pulse is associated with lightheadedness, dizziness, or feeling faint.
Sometimes, the heart rate appears disproportionate to the actual fever, rising much faster than expected. This can indicate a more severe underlying issue, such as severe dehydration, a cardiovascular complication, or a widespread infection like sepsis. Fluttering or pounding sensations in the chest, known as palpitations, also suggest an underlying rhythm disturbance that needs assessment.
Practical Steps for Monitoring and Managing Your Pulse
Tracking your pulse while ill is a straightforward way to monitor your body’s response and recovery. You can manually check your pulse by placing your index and middle fingers on the inside of your wrist below the thumb, counting the beats for a full minute. Many wearable devices and pulse oximeters also provide accurate readings that can be helpful for tracking trends.
Simple strategies can often help bring a non-dangerous elevated pulse down. The most direct action is ensuring adequate hydration by drinking plenty of water, clear broth, or electrolyte solutions. Replacing lost fluids increases the blood volume, which reduces the need for the heart to pump faster.
Getting sufficient rest is paramount, as physical activity requires the heart to work harder. Reducing a fever with over-the-counter fever reducers will often lower the heart rate, addressing the original physiological trigger. By consistently monitoring your pulse and taking these self-care steps, you can support your body’s fight against illness while watching for any signs that require professional care.