Being sick with a cold, flu, or other infection can temporarily raise your blood pressure by several points, even if it’s normally well controlled. This happens because your immune system’s response to infection triggers a chain of events that tightens blood vessels, increases heart rate, and shifts how your kidneys handle sodium and water. The good news: most of the spike is temporary, and there are straightforward ways to keep it in check while you recover.
Why Illness Raises Blood Pressure
When your body fights off a virus, the immune response releases inflammatory signals that cause blood vessels to constrict. At the same time, infection can disrupt a hormone system in your kidneys that regulates blood pressure, leading to higher levels of a protein called angiotensin II. This protein narrows blood vessels further and tells your kidneys to hold onto more sodium and water. Studies on influenza patients found markedly increased levels of this blood pressure-raising protein compared to healthy controls.
Fever adds its own layer. It raises your heart rate, shifts fluid balance, and increases your body’s overall metabolic demand. Pain and poor sleep pile on stress hormones that push readings higher still. If you already have high blood pressure, these combined effects can send your numbers into uncomfortable territory.
Stay Hydrated, but Strategically
Dehydration is common during illness from fever, sweating, vomiting, or simply not drinking enough. Losing fluid triggers your nervous system to compensate by increasing heart rate and constricting blood vessels to maintain circulation. Research shows that even moderate fluid loss (around 3% of body weight) significantly increases heart rate responses and activates the same stress pathways that raise blood pressure.
Drink water, broth, or electrolyte drinks steadily throughout the day rather than in large amounts at once. If you’re running a fever, your fluid needs are higher than normal. One practical gauge: your urine should stay pale yellow. Dark urine means you need more fluids. Avoid relying on caffeinated beverages as your primary source, since caffeine can nudge blood pressure up on its own.
Choose the Right Pain and Fever Relievers
Acetaminophen (Tylenol) is the safest choice for fever and body aches when blood pressure is a concern. Anti-inflammatory drugs like ibuprofen (Advil, Motrin) and naproxen (Aleve) raise systolic blood pressure by an average of 2 mmHg compared to acetaminophen. That number climbs to 6 mmHg in people taking beta blockers for their blood pressure. If you’re already running high, that extra push matters.
One hidden trap: effervescent or dissolving tablets. Many fizzy cold and pain products contain enormous amounts of sodium as part of their dissolving agent. A single effervescent pain or cold tablet can contain 450 to 575 mg of sodium. Taking the maximum recommended daily dose of a product like Alka-Seltzer Classic delivers 3,560 mg of sodium, which is 178% of the entire daily recommended limit. One study found that effervescent acetaminophen tablets containing 545 mg of sodium per dose raised 24-hour systolic blood pressure by 5 mmHg. If you take acetaminophen, choose standard swallowable tablets or capsules instead of dissolving formulations.
Avoid Decongestants That Spike Blood Pressure
Pseudoephedrine (Sudafed) and phenylephrine, the active ingredients in most oral decongestants, work by constricting blood vessels in your nasal passages to reduce swelling. The problem is they constrict blood vessels everywhere else too. This mechanism directly raises blood pressure, and the effect can last for hours with each dose. People often take these medications daily for a week or more during a cold, compounding the risk.
For a stuffy nose, saline nasal spray is the safest alternative. It loosens mucus and reduces congestion without any blood pressure effect. Nasal corticosteroid sprays (like Flonase) are another option that works locally without systemic effects on your cardiovascular system. Steam inhalation from a hot shower or a bowl of hot water with a towel over your head can also provide temporary relief.
Watch Multi-Symptom Cold Products
Combination cold and flu products are particularly risky because they bundle multiple active ingredients together. A single “nighttime cold relief” capsule might contain acetaminophen, a decongestant, a cough suppressant, and an antihistamine. The decongestant hiding inside can raise your blood pressure without you realizing it. Always read the “active ingredients” panel on the box. If you see pseudoephedrine or phenylephrine listed, choose a different product.
Some cough suppressants containing dextromethorphan (the “DM” in many brand names) are generally fine at normal doses but can raise blood pressure and heart rate at higher amounts. Stick to the recommended dose and don’t double up by taking two products that both contain it.
Breathing Techniques for Quick Relief
Slow, controlled breathing can produce a measurable drop in blood pressure within minutes. Research shows that a single 10-minute session of slow breathing temporarily lowers both systolic and diastolic blood pressure as well as heart rate. The technique works by activating your body’s natural pressure-regulating reflexes and calming the stress response that illness amplifies.
A simple approach: breathe in slowly through your nose for about 6 seconds, hold gently for 6 seconds, then exhale slowly for 6 seconds. Repeat this cycle for 10 minutes. You can do this lying in bed while sick. It won’t replace medication or other measures, but it helps take the edge off a temporary spike, especially if anxiety about your readings is making things worse.
Keep Taking Your Blood Pressure Medications
If you’re already on blood pressure medication, don’t skip doses while sick. Some people worry about their readings dropping too low, but stopping medication abruptly is far more dangerous than continuing it during an illness. If you’re vomiting and can’t keep pills down for more than a day, contact your prescriber about alternative options.
Be aware that some cold medications interact with blood pressure drugs. NSAIDs like ibuprofen can blunt the effectiveness of ACE inhibitors and calcium channel blockers, leading to a 3 mmHg systolic increase on top of the drug’s own blood pressure effect. This is another reason to stick with acetaminophen when possible.
Rest and Reduce Physical Demand
Your cardiovascular system is already working harder than usual during illness. Fever alone can increase your resting heart rate by 10 beats per minute for every degree of temperature elevation. Trying to push through your normal routine, exercising, or even standing for long periods adds to the load. Resting in a comfortable, slightly elevated position (propping yourself up with pillows) helps your heart work more efficiently and can keep readings lower than lying completely flat, especially if congestion is an issue.
Reducing sodium intake from food also helps during illness. Canned soups, a go-to sick food, are notoriously high in sodium. A single can of chicken noodle soup can contain over 1,500 mg. If you’re craving soup, look for low-sodium versions or make broth at home where you can control the salt.
When Blood Pressure During Illness Is an Emergency
A reading of 180/120 mmHg or higher is a hypertensive crisis. If you see this number and have any of the following symptoms, call 911 immediately: chest pain, severe headache, vision changes, difficulty speaking, sudden weakness on one side of your body, confusion, or seizures. These signs indicate that the high pressure may be damaging your organs.
If your reading hits 180/120 but you feel relatively okay, sit down, take slow breaths, and recheck after 5 minutes. A single high reading during illness, especially if you just took a decongestant or are in pain, may come down once those factors are addressed. But if it stays at or above 180/120 on a second reading, you need emergency care regardless of symptoms.