A cold or flu infection places physical demands on the body that can temporarily increase blood pressure, a concern for anyone, especially those managing hypertension. When the body fights a virus, the coordinated immune response often results in a measurable, short-term elevation of systolic and diastolic pressure readings. Understanding the mechanisms behind this temporary spike is important for safe self-care and knowing when to seek professional medical attention.
How the Body’s Response to Illness Raises Blood Pressure
The immune system initiates a complex response to fight off a cold or flu, directly affecting the cardiovascular system. As the body mobilizes defenses, it triggers systemic inflammation, releasing signaling molecules called cytokines into the bloodstream. This inflammation can cause blood vessel walls to tighten (vasoconstriction), increasing resistance to blood flow and raising blood pressure.
An infection also activates the body’s stress response, releasing hormones like adrenaline (epinephrine) and cortisol from the adrenal glands. Adrenaline increases both the heart rate and the force of heart contractions, requiring the heart to work harder to circulate blood. Cortisol helps regulate inflammation but also contributes to elevated blood pressure by affecting the vascular system.
Fever, a common flu symptom, further increases the heart’s workload. As body temperature rises, the metabolic rate increases, demanding more oxygen and energy. To meet this demand, the heart must pump blood faster and with greater force, contributing to the temporary rise in blood pressure. The physical strain of fighting the infection, coupled with dehydration, places additional stress on the cardiovascular system.
The Role of Common Cold and Flu Medications
Many over-the-counter (OTC) cold and flu products contain ingredients that can independently raise blood pressure. Decongestants are the most common culprits, as they are designed to narrow blood vessels in the nasal passages to reduce swelling and clear congestion. These medications, known as sympathomimetics, often contain pseudoephedrine or phenylephrine.
Pseudoephedrine is particularly effective at constricting blood vessels and stimulating the cardiovascular system, increasing heart rate and systemic blood pressure. Phenylephrine acts similarly, though its effect on systemic blood pressure is less pronounced when taken orally due to poor absorption and metabolism. Because these decongestants mimic the effects of stress hormones, they add to the body’s existing stress response, potentially causing an unsafe spike in blood pressure, especially for individuals with pre-existing hypertension.
Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, are frequently included in remedies to treat pain and fever. These drugs can raise blood pressure by causing the body to retain salt and water, a condition known as fluid retention. This increased fluid volume adds strain to the kidneys and heart, which can elevate blood pressure, sometimes by an average of 5 millimeters of mercury (mmHg). NSAIDs can also interfere with the effectiveness of certain prescription blood pressure medications, making hypertension control difficult.
Monitoring Blood Pressure and Seeking Medical Care
Anyone with hypertension should be highly selective when choosing cold and flu remedies, actively avoiding products containing decongestants like pseudoephedrine or phenylephrine. Instead, look for alternatives labeled as “safe for people with high blood pressure” or opt for symptom relief using a single-ingredient pain reliever like acetaminophen. Saline nasal sprays or strips offer congestion relief without the systemic cardiovascular side effects of oral decongestants.
Continue taking all prescribed blood pressure medications as directed by a healthcare provider. During an illness, monitor blood pressure more frequently than usual, recording readings to share with a doctor. A temporary rise is common, but sustained high readings warrant medical attention.
Call emergency services immediately if blood pressure readings reach 180/120 mmHg or higher, which is considered a hypertensive emergency. This extreme elevation is especially concerning if accompanied by severe symptoms like chest pain, severe headache, shortness of breath, numbness, weakness, or difficulty speaking. These symptoms can indicate a serious event like a stroke or heart attack and require immediate intervention.