High Blood Pressure Does Not Directly Cause Fever
High blood pressure and fever are separate conditions with different causes. High blood pressure (hypertension) is a chronic condition where the force of blood against artery walls stays elevated over time. Fever is a temporary rise in body temperature, usually a sign that your body is fighting an infection or responding to inflammation. One does not cause the other.
That said, the two can occur together — but when they do, a third condition is usually responsible. For example, a kidney infection can raise both blood pressure and body temperature at the same time. Understanding the difference matters because treating high blood pressure will not lower a fever, and treating a fever will not control high blood pressure.
Key Takeaways
- High blood pressure itself does not produce fever; they are separate conditions with different underlying causes.
- When fever and high blood pressure appear together, an infection or inflammatory condition is usually the real cause of both.
- Certain blood pressure medications can occasionally trigger a fever-like reaction, though true fever is rare.
- If you have high blood pressure and develop a fever, the fever needs its own investigation rather than assuming it is related to your hypertension.
When High Blood Pressure and Fever Occur at the Same Time
If you have high blood pressure and suddenly develop a fever, something else is happening in your body — not the high blood pressure itself. Common causes include urinary tract infections, pneumonia, kidney infections, and other bacterial or viral infections. These conditions can raise body temperature and also temporarily elevate blood pressure as your body mounts an immune response.
Inflammatory conditions like rheumatoid arthritis or lupus can also produce both symptoms. In these cases, treating the underlying infection or inflammation addresses both the fever and the blood pressure spike. Once the infection clears or inflammation subsides, blood pressure often returns to its baseline level.
Blood Pressure Medications and Fever-Like Symptoms
Some blood pressure medications can trigger reactions that feel like fever or produce a low-grade temperature. ACE inhibitors and certain other classes of antihypertensive drugs occasionally cause drug fever — a true fever caused by the medication itself rather than infection. This is uncommon but does happen.
If you started a new blood pressure medication and then developed a fever within days or weeks, mention both facts to your doctor. Do not stop taking the medication on your own, but do report the timing. Your doctor may switch you to a different medication or investigate whether something else is causing the fever. Drug fever typically resolves once the offending medication is stopped.
Hypertensive Crisis and High Temperature
A hypertensive crisis — a sudden, dangerous spike in blood pressure — can produce symptoms like chest pain, shortness of breath, severe headache, and blurred vision. It does not typically cause fever. If you experience a hypertensive crisis along with a high temperature, the fever is a separate problem requiring separate attention.
Hypertensive crisis is a medical emergency. If your blood pressure is very high (usually 180/120 or higher) and you have chest pain, difficulty breathing, or severe headache, call 911 or go to an emergency room when ready. If you also have a fever, tell the emergency team about both symptoms so they can investigate the fever's cause while managing the blood pressure emergency.
What to Do If You Have Both High Blood Pressure and a Fever
First, take your temperature to confirm you actually have a fever (typically 100.4°F or higher). Then contact your primary care doctor or an urgent care clinic. Describe both the fever and your blood pressure history so they can determine what is causing the fever.
Bring a list of any blood pressure medications you take, including when you started them. If you have recently started a new medication, mention that. Your doctor may check for signs of infection, review your medications, or order blood tests to find the cause. Do not assume the fever is related to your high blood pressure — it almost certainly is not, and treating it as a separate condition will get you answers faster.
Common Infections That Raise Both Blood Pressure and Temperature
Kidney infections are a frequent culprit. They produce fever, back pain, and painful urination — and they also raise blood pressure temporarily. Urinary tract infections can do the same, though usually with milder symptoms. Pneumonia and other respiratory infections often cause fever and can elevate blood pressure as your body fights the infection.
Sepsis — a life-threatening response to infection — produces high fever and can cause dangerous blood pressure changes (either very high or dangerously low). Sepsis is rare but serious and requires emergency care. If you have a high fever, confusion, rapid heartbeat, or difficulty breathing, seek emergency care when ready.
When to Contact Your Doctor
Contact your doctor if you have a fever above 100.4°F that lasts more than a few days, or if fever appears alongside other symptoms like cough, painful urination, back pain, or severe headache. Also contact your doctor if you recently started a blood pressure medication and then developed a fever, even a low-grade one.
Seek emergency care (call 911 or go to the nearest emergency room) if you have a very high fever (above 103°F), severe headache with a stiff neck, chest pain, difficulty breathing, confusion, or signs of a hypertensive crisis. These symptoms need when ready evaluation and are not something to manage at home.
Frequently Asked Questions
Can blood pressure medication cause a real fever?
Yes, though it is uncommon. Some blood pressure medications, particularly ACE inhibitors, can trigger drug fever — a true fever caused by the medication rather than infection. If you started a new blood pressure medication and developed a fever shortly after, tell your doctor. Do not stop the medication yourself, but report the timing so your doctor can investigate.
Does a fever raise blood pressure temporarily?
Yes. Fever itself can cause a temporary rise in blood pressure as your body's metabolic rate increases and your heart works harder. This is normal and usually resolves once the fever breaks. If your blood pressure stays high after the fever is gone, that is a separate issue worth discussing with your doctor.
What if I have high blood pressure and a fever but no other symptoms?
Contact your doctor. A fever without obvious symptoms still signals that something is happening in your body — often an infection in its early stages. Your doctor can examine you and run tests if needed. Do not assume it will go away on its own, especially if you have a chronic condition like high blood pressure.
Is it safe to take fever-reducing medication if I have high blood pressure?
Most over-the-counter fever reducers like acetaminophen are safe for people with high blood pressure. Ibuprofen and naproxen can raise blood pressure in some people, especially with long-term use, so ask your doctor before using them. Always tell your pharmacist about your high blood pressure when buying any over-the-counter medication.