The Body's Fight-or-Flight Response and Blood Pressure
When you get sick, whether with a common cold, the flu, or another infection, your body activates its immune system to fight off the illness. This intensive process is perceived by your body as a form of physical stress. As a result, your adrenal glands release stress hormones such as adrenaline and cortisol, triggering the body’s 'fight-or-flight' response. This hormonal surge causes your heart rate to increase and your blood vessels to constrict, or narrow. Both of these actions increase the force with which blood pushes against the artery walls, which is measured as a rise in blood pressure. For most healthy individuals, this is a temporary and normal physiological response that subsides once the illness resolves.
How Different Illness Factors Affect Your Blood Pressure
Beyond the general stress response, several specific symptoms and effects of being sick can directly impact your blood pressure.
Fever and Increased Heart Rate
Fever is a common symptom of many illnesses and a clear sign your body is battling an infection. The increase in body temperature causes your heart to beat faster, pumping blood more rapidly to circulate heat and immune cells throughout your body. This increased workload on the heart directly contributes to a temporary rise in your blood pressure reading.
Dehydration and Blood Volume
Illness-related symptoms like fever, vomiting, and diarrhea can lead to a significant loss of fluids, resulting in dehydration. Your body's blood volume decreases when you're dehydrated. To compensate for the reduced volume, your heart has to work harder to circulate the remaining blood, which becomes thicker and more concentrated. This compensatory mechanism can cause a temporary spike in blood pressure. Conversely, severe dehydration can sometimes lead to dangerously low blood pressure.
Inflammation and Blood Vessels
As part of the immune response to an infection, the body releases chemicals that cause inflammation. While this process is vital for healing, widespread or persistent inflammation can cause blood vessels to become stiffer and narrower, increasing the resistance to blood flow and raising blood pressure. Conditions like chronic respiratory infections or certain autoimmune disorders can prolong this effect.
Common Medications That Can Raise Blood Pressure
Many over-the-counter and prescription medications used to treat cold and flu symptoms can have a significant effect on blood pressure. These are especially concerning for those with pre-existing hypertension.
- Decongestants: Common decongestants like pseudoephedrine and phenylephrine work by narrowing blood vessels in your nose to reduce swelling. This effect is not localized and can constrict blood vessels throughout your body, leading to an increase in blood pressure. Many cold and flu formulations contain these ingredients, so it is crucial to read the label carefully.
- NSAIDs: Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen, used for pain and fever, can cause the body to retain salt and water, which raises blood pressure. Acetaminophen (Tylenol) is often a safer alternative for those with high blood pressure.
- Other Medications: Certain antidepressants, steroids, and some herbal supplements can also affect blood pressure levels.
Temporary Spike vs. Chronic Concern: A Comparison
| Factor | Healthy Individual | Individual with Hypertension |
|---|---|---|
| Effect of Illness | Experiences a temporary and mild increase in BP that returns to normal after recovery. | Faces a greater risk of a significant and potentially dangerous spike in BP. |
| Medication Risks | Generally minimal effect from common OTC medications. | Must avoid certain medications (like decongestants) that could dangerously raise BP. |
| Actionable Steps | Focus on rest, hydration, and treating symptoms. Monitoring is less critical but can be done. | Requires consistent and careful blood pressure monitoring and consultation with a doctor. |
| When to Worry | If the BP spike is severe or accompanied by chest pain or vision changes. | At any sign of persistent high readings, symptoms of a hypertensive crisis, or other concerning changes. |
The Surprising Flip Side: When Illness Lowers Blood Pressure
While an increase in blood pressure is common during illness, some conditions can cause it to drop. In severe cases of infection, such as septic shock, the body's response can cause blood vessels to dilate widely, leading to a dangerous drop in blood pressure. Additionally, severe dehydration from persistent vomiting or diarrhea can cause blood pressure to fall. Symptoms of low blood pressure include dizziness, lightheadedness, and fainting. This underscores the unpredictable and variable nature of how illness affects the body's cardiovascular system.
Managing Your Blood Pressure When Sick
Managing your health carefully when ill is especially important if you have a history of high blood pressure. Here are some strategies to help.
- Monitor Your Blood Pressure: If you have hypertension, continue to take your readings as usual while you are sick. This helps you and your doctor track any significant changes. Keep a log of your readings to share with a healthcare provider if needed.
- Stay Hydrated: Drinking plenty of fluids, such as water, broth, and electrolyte solutions, can help prevent dehydration and support healthy blood volume. Adequate hydration is one of the most effective ways to manage fever and sickness.
- Choose Medications Carefully: Always check the labels of over-the-counter cold and flu medications. If you have high blood pressure, opt for formulas specifically marked for individuals with hypertension. Avoid decongestants and choose acetaminophen for fever and pain relief instead of NSAIDs. If in doubt, consult a pharmacist or your doctor.
- Prioritize Rest: Resting gives your body the energy it needs to fight the infection without putting extra strain on your heart. Avoid strenuous activity and allow your body to recover.
- Manage Stress: Anxiety about being sick can further elevate blood pressure. Practicing relaxation techniques like deep breathing or meditation can help manage stress levels. For more information on stress and blood pressure, visit the American Heart Association website.
When to Seek Medical Attention
While a temporary increase in blood pressure during an illness is often no cause for alarm, certain symptoms warrant immediate medical attention. Call your doctor if you experience persistently high readings, especially if they are over 180/120 mmHg. You should also seek medical help if you experience any of the following alongside high blood pressure when you are sick: chest pain, shortness of breath, severe headache, confusion, or changes in vision.
Conclusion
The short answer to the question, "Does your blood pressure go up when you are sick?" is yes, it can, and for a variety of reasons. Illness, fever, dehydration, and certain medications can all contribute to a temporary spike in your blood pressure. For most people, this is a normal part of the body's response and resolves with recovery. However, for those with pre-existing hypertension or other cardiovascular issues, it requires careful monitoring and management. By staying informed and proactive, you can navigate illness safely and protect your heart health.
