Being sick can cause a temporary elevation in blood pressure. Blood pressure is measured by two numbers: systolic pressure (force when the heart beats) and diastolic pressure (pressure when the heart rests). A short-term illness, such as a cold or the flu, may lead to an acute spike, but these readings usually return to normal once the illness resolves. Understanding the difference between a temporary spike and sustained high blood pressure (hypertension) is important for managing your health.
The Body’s Acute Response to Illness
An acute illness triggers a systemic reaction that affects the cardiovascular system. This response is mediated by the activation of the sympathetic nervous system, known as the “fight or flight” response. The body perceives infection as a stressor, leading to the release of powerful hormones.
The adrenal glands release catecholamines, such as adrenaline and noradrenaline, in response to this stress. These hormones cause the heart to beat faster and with greater force. They also constrict many of the body’s smaller blood vessels, and this combination of increased cardiac output and narrowed vessels immediately raises blood pressure.
In addition to the hormonal response, illness causes systemic inflammation as the immune system fights the infection. Inflammatory molecules circulating in the bloodstream can alter the function of the blood vessel lining. This temporary change in vascular function contributes to the acute elevation in blood pressure. These physiological changes typically subside as the infection clears.
Medications That Affect Blood Pressure
Over-the-counter (OTC) medications used to treat cold and flu symptoms often cause temporary blood pressure spikes. Decongestants are particularly noteworthy because they contain ingredients designed to narrow blood vessels. While this action reduces swelling in the nasal passages and alleviates congestion, it affects the entire body.
Ingredients like pseudoephedrine and phenylephrine constrict blood vessels systemically, which increases blood pressure. Pseudoephedrine works by stimulating adrenergic receptors, leading to vasoconstriction. Individuals who already have high blood pressure should be cautious with these products.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, can also interfere with blood pressure regulation, especially with consistent use. These pain relievers may impair kidney function by reducing blood flow. This effect can lead to the retention of sodium and fluid, which directly contributes to higher blood pressure readings. Checking product labels for warnings is advisable for individuals managing hypertension.
Sustained High Blood Pressure Due to Underlying Chronic Illness
While acute illness causes temporary spikes, certain long-term conditions can lead to sustained, or secondary, hypertension. This form of high blood pressure is a symptom of a deeper medical problem that does not resolve when a short-term illness ends. The most common cause of secondary hypertension is chronic kidney disease (CKD).
When the kidneys are damaged, their ability to regulate fluid volume and salt balance becomes impaired. Failure to properly excrete sodium and water results in volume expansion, placing constant pressure on the circulatory system. Kidney damage can also trigger the activation of the renin-angiotensin-aldosterone system, a hormonal pathway that constricts blood vessels and further elevates pressure.
Chronic inflammatory and autoimmune diseases, such as systemic lupus erythematosus or rheumatoid arthritis, also increase the risk of sustained hypertension. The chronic systemic inflammation involved in these conditions can cause lasting damage to the arterial walls, leading to stiffness and dysfunction. This ongoing vascular injury contributes to persistently elevated blood pressure, requiring dedicated medical management.
When to Monitor and Seek Medical Attention
Individuals with pre-existing hypertension should monitor their blood pressure more frequently when they are sick. Temporary spikes should be noted and discussed with a healthcare provider. It is important to inform your doctor about all over-the-counter medications you are taking, as decongestants and certain pain relievers can interfere with prescribed blood pressure drugs.
A severe and sudden spike in blood pressure warrants immediate medical consultation. A reading of 180/120 mmHg or higher is classified as a hypertensive crisis and requires prompt attention. This is considered a medical emergency if accompanied by symptoms.
Symptoms of Hypertensive Crisis
- Chest pain
- Severe headache
- Confusion
- Sudden shortness of breath
If you record a reading this high, rest for a few minutes and recheck; if the number remains elevated, seek emergency medical care.