A systolic reading of 173 mm Hg is firmly in the range of Stage 2 hypertension, a category that begins at 160/100 mm Hg and carries a meaningfully elevated risk of heart attack, stroke, and other cardiovascular events. That said, a single reading in a clinic or at home does not necessarily mean you need to rush to the emergency room. The distinction between “very high but manageable” and “get help now” depends on symptoms, how long the pressure has been elevated, and whether vital organs are showing signs of strain.
Where 173 Falls on the Scale
Blood pressure is reported as two numbers: systolic (the higher number, measuring pressure when your heart contracts) and diastolic (the lower number, between beats). A systolic reading of 173 exceeds the threshold for Stage 2 hypertension, which is defined as blood pressure at or above 160/100 mm Hg and is most often found in older adults who already face elevated cardiovascular risk.1PubMed Central. Treating stage 2 hypertension The diastolic number matters too. If your reading is 173/95, the systolic alone is enough to classify you in Stage 2, even though 95 would be lower-stage by itself. The higher of the two numbers determines your category.
For context, normal blood pressure sits below 120/80. Elevated is 120–129 systolic with a diastolic under 80. Stage 1 hypertension covers 130–139 systolic or 80–89 diastolic. Stage 2 starts at 140/90 under current U.S. guidelines, though some classification systems use 160/100 as the Stage 2 cutoff. Under any framework, 173 is well past the line.
Is It an Emergency?
This is probably the question weighing on you most, and the answer hinges almost entirely on how you feel right now. A blood pressure of 173 with no symptoms is treated very differently from 173 with chest pain, sudden vision changes, or trouble speaking. The critical distinction in clinical practice is between very high blood pressure that is causing acute organ damage and very high blood pressure that is not.
Hypertensive emergencies involve readings usually above 180/110 along with active damage to the brain, heart, kidneys, or blood vessels. The ESC Council on Hypertension has noted that when patients present with very high readings but no signs of organ damage, outcomes are not necessarily worse than those of patients with uncontrolled hypertension managed in an outpatient setting, and emergency department referral does not appear to improve blood pressure control or cardiovascular outcomes at six months.2European Heart Journal – Cardiovascular Pharmacotherapy. ESC Council on hypertension position document on the management of hypertensive emergencies In other words, if you are symptom-free at 173 systolic, you are not in the same danger zone as someone at 173 with a splitting headache and blurred vision. That does not mean you can ignore it. It means you should contact your doctor promptly rather than call an ambulance.
If you do have symptoms, take them seriously. In studies of hypertensive crises, the most common complaints were headache (reported in about three-quarters of patients), chest pain and shortness of breath (about two-thirds), dizziness (about half), and nausea or vomiting (roughly four in ten).3PubMed Central. Clinical presentation of hypertensive crises in emergency medical services When organ damage accompanies severely elevated pressure, the most frequent complications include stroke, acute fluid buildup in the lungs, and brain swelling from high pressure.4PubMed. Hypertensive urgencies and emergencies. Prevalence and clinical presentation Any combination of sudden confusion, difficulty speaking, severe headache unlike anything you have experienced, chest tightness, or visual disturbance alongside a reading of 173 or higher warrants an immediate call to emergency services.
Could the Reading Be Wrong?
Before making decisions based on a single reading, it is worth considering whether the number you saw actually reflects your resting blood pressure. Measurement technique matters more than most people realize. Research has shown that factors like talking during the reading, having your arm positioned too low or too high, using the wrong cuff size, recent alcohol intake, and exposure to cold can each distort a reading by more than 5 mm Hg.5BMJ. Measurement of blood presssure: an evidence based review Those errors can stack. If you talked during the measurement with your arm hanging at your side and a slightly too-small cuff, you could easily see a reading inflated by 10 to 15 points.
Then there is the white-coat effect, which can raise blood pressure by more than 20 points systolic in up to 40 percent of patients.5BMJ. Measurement of blood presssure: an evidence based review If your 173 came from a nervous visit to the doctor’s office, it may not represent your usual blood pressure at all. This is one reason ambulatory blood pressure monitoring, where you wear a portable cuff that takes readings throughout a normal day, is considered the gold standard for confirming whether high readings in the office reflect reality.6PubMed Central. When and how to use ambulatory blood pressure monitoring and home blood pressure monitoring for managing hypertension If you own a home blood pressure monitor, taking several readings over a few days (sitting quietly for five minutes first, arm supported at heart level, bladder empty, no caffeine in the prior 30 minutes) will give you a much clearer picture than any single clinic number.
What Causes a Spike to 173
Plenty of people discover a reading of 173 during a routine check and wonder what pushed it so high. Chronic high blood pressure usually builds over years, driven by a combination of genetics, diet (especially sodium and alcohol intake), weight, inactivity, and aging. But acute spikes can be layered on top of that baseline by several triggers.
A variety of medications and substances can push blood pressure up, sometimes sharply. These agents generally work by causing your body to hold onto sodium and expand fluid volume, by stimulating the nervous system, or by acting directly on the smooth muscle of small arteries.7JAMA Internal Medicine. High Blood Pressure: A Side Effect of Drugs, Poisons, and Food Common culprits include over-the-counter anti-inflammatory drugs like ibuprofen and naproxen, decongestants containing pseudoephedrine, certain antidepressants, oral contraceptives, and stimulants including high-dose caffeine. Abruptly stopping some blood pressure medications can also trigger a rebound spike.8Archives of Internal Medicine. High Blood Pressure: A Side Effect of Drugs, Poisons, and Food Pain, a full bladder, anxiety, and even the stress of having your blood pressure taken can each add points to the reading. If you saw 173 on a day when you were in pain, had recently taken a decongestant, and were anxious about the reading itself, the “real” resting number could be substantially lower.
In a small fraction of cases, persistently high blood pressure in the 170s or above is caused by a treatable underlying condition. Roughly one in ten cases of hypertension, particularly when it develops early in adulthood or is resistant to standard drugs, traces to a secondary cause such as hormonal overproduction by the adrenal glands, narrowing of the arteries that supply the kidneys, or a structural heart abnormality.9PubMed. Diagnostic and Therapeutic Approach to the Major Secondary Causes of Arterial Hypertension in Young Adults: A Narrative Review These are worth investigating when blood pressure is difficult to control, when it worsens suddenly after years of being normal, or when it first appears at an unusually young age.
Why 173 Systolic Matters Even Without Symptoms
High blood pressure earned its reputation as a “silent killer” precisely because it can damage the body for years before symptoms appear. The organs most vulnerable are the heart, brain, kidneys, eyes, and large blood vessels.10PubMed Central. The burden of uncontrolled hypertension: morbidity and mortality associated with disease progression Left uncontrolled, sustained pressure in this range increases the likelihood of heart failure, atrial fibrillation, chronic kidney disease, dementia, and aortic problems on top of the more widely known risks of heart attack and stroke.11PubMed Central. High Blood Pressure and Cardiovascular Disease
The relationship between systolic blood pressure and bad outcomes is not a simple on-off switch at some threshold; it is a gradient. In research on older adults with isolated systolic hypertension, every additional 10 mm Hg of systolic pressure was associated with a roughly 26 percent higher risk of death and a 22 percent higher risk of stroke.12The Lancet. Risks associated with systolic blood pressure in treated and untreated older patients with isolated systolic hypertension and overview of randomised trials That means someone sitting at 173 faces meaningfully greater risk than someone at 153, who in turn faces more risk than someone at 133. Every bit of reduction counts.
What to Do Right Now
If your reading of 173 just happened and you feel fine, take a breath. Sit quietly for five minutes and re-measure. If the number stays in the 170s across two or three readings, call your doctor’s office and describe the reading. You will likely be asked to come in within the next day or two. Severe, asymptomatic readings do not generally benefit from being slammed down in an emergency department; a controlled trial found that aggressive oral drug loading to rapidly reduce high but symptom-free blood pressure offered no clear advantage and carried a small but real risk of complications from dropping pressure too fast.13PubMed. Rapid reduction of severe asymptomatic hypertension. A prospective, controlled trial The goal is to bring the pressure down in a controlled way over days to weeks, not in the next hour.
If you already take blood pressure medication and your reading is 173, check whether you missed a dose. A skipped pill, especially of a beta blocker or a short-acting agent, is one of the most common explanations for an unexpected spike. Do not double up on your medication without talking to your prescriber. Take your usual dose, rest, and check again in an hour or two.
Treatment at This Level
For Stage 2 hypertension, current guidelines typically recommend starting medication and lifestyle changes at the same time, rather than trying lifestyle alone first. The evidence supports beginning with two blood pressure drugs from different classes rather than a single drug, because a combination approach brings pressure down more effectively and reaches target levels faster.14Blood Pressure Monitoring. Improving blood pressure control and clinical outcomes through initial use of combination therapy in stage 2 hypertension In clinical trials comparing two common two-drug combinations in patients with Stage 2 hypertension, systolic pressure dropped by roughly 32 to 36 mm Hg over six weeks, and nearly all participants reached their blood pressure targets.15PubMed. Tolerability and blood pressure-lowering efficacy of the combination of amlodipine plus valsartan compared with lisinopril plus hydrochlorothiazide in adult patients with stage 2 hypertension A drop of that magnitude would bring a reading of 173 down into the 137–141 range within weeks, with further reductions possible as doses are adjusted.
The most commonly used drug classes include ACE inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, and thiazide diuretics. Your doctor picks a combination based on your age, kidney function, other medications, and whether you have conditions like diabetes or heart failure that favor one class over another. Side effects vary by class but are generally manageable, and switching is common if the first combination does not suit you.
Lifestyle Changes That Move the Needle
Medication handles most of the heavy lifting when systolic pressure is in the 170s, but lifestyle modifications contribute genuine additional reductions and are part of every guideline. The most impactful changes are sodium reduction, weight loss if you are above a healthy weight, regular aerobic exercise, and a dietary pattern rich in fruits, vegetables, and low-fat dairy.
Research on a combined approach (the DASH diet plus reduced sodium intake) has shown that the effects stack with baseline blood pressure. Among people who started with the highest blood pressures, the combination of a low-sodium DASH diet versus a typical high-sodium American diet was associated with a systolic drop of roughly 21 mm Hg.16PubMed Central. Effects of Sodium Reduction and the DASH Diet in Relation to Baseline Blood Pressure For someone at 173, that kind of reduction on top of medication could be the difference between staying above target and reaching it. An 18-month randomized trial found that participants who adopted comprehensive lifestyle changes, including weight loss, reduced sodium and fat, and increased physical fitness, had about 23 percent lower odds of still having hypertension compared with those given advice alone.17PubMed. Effects of comprehensive lifestyle modification on diet, weight, physical fitness, and blood pressure control: 18-month results of a randomized trial
Alcohol deserves special mention. Even moderate drinking raises blood pressure, and cutting back consistently lowers it. If you drink regularly, reducing intake is one of the most straightforward and effective changes you can make.
Why the Systolic Number Tends to Climb With Age
If you are over 50, there is a good chance your diastolic number is normal or even low while your systolic number is the one causing trouble. This pattern, called isolated systolic hypertension, is the most common form of high blood pressure in older adults. It happens because the large arteries, especially the aorta, stiffen with age. When the aorta loses its elasticity, it can no longer cushion the pressure wave from each heartbeat, so the peak pressure (systolic) rises while the trough (diastolic) may actually fall.18PubMed Central. The conundrum of arterial stiffness, elevated blood pressure, and aging Studies have confirmed that people with isolated systolic hypertension have stiffer aortas and impaired blood vessel function compared with age-matched people with normal blood pressure.19PubMed. Isolated systolic hypertension is characterized by increased aortic stiffness and endothelial dysfunction
This matters practically because treating the high systolic number in isolation can sometimes push the already-low diastolic number even further down, which raises concerns about inadequate blood flow to the heart and brain. In frail older adults, strict systolic control may cause syncope, falls, electrolyte problems, acute kidney injury, and fractures.20PubMed Central. Hypertension in frail older adults: current perspectives Treatment targets for people over 75 or 80 are often more relaxed than for younger adults, with the tradeoff between stroke prevention and fall risk receiving careful individual consideration.
The Morning Surge Problem
Blood pressure is not a fixed number. It follows a daily rhythm, dipping during sleep and rising sharply in the early morning hours. For some people, the morning surge is dramatic. In a study of older adults with hypertension, those whose morning surge exceeded 55 mm Hg had nearly triple the rate of stroke compared with those whose surge was smaller, even after accounting for differences in 24-hour blood pressure.21PubMed. Morning surge in blood pressure as a predictor of silent and clinical cerebrovascular disease in elderly hypertensives: a prospective study If your 173 reading came first thing in the morning, it may represent the peak of a surge rather than your average daytime level. That does not make it harmless. The surge itself appears to be an independent risk factor for stroke, which means controlling it is part of good blood pressure management.
This is another reason ambulatory monitoring, or at least home readings at different times of day, provides a much more useful picture than a single office reading. If your numbers are consistently in the 170s across multiple time points over several days, the urgency of treatment is higher than if 173 was a one-time morning spike that settles to the 140s by afternoon.
173 During Pregnancy
Blood pressure management during pregnancy uses different thresholds and carries unique stakes. A systolic reading of 173 during pregnancy is a medical emergency and requires immediate evaluation, because very high blood pressure in pregnancy can rapidly progress to preeclampsia or eclampsia, both of which threaten the life of both the mother and the baby. Research has shown that elevated mean arterial pressure during the second trimester is associated with a significantly higher risk of developing severe preeclampsia later in pregnancy.22PubMed. Elevated midtrimester mean arterial blood pressure in women with severe preeclampsia If you are pregnant and see a systolic number in the 170s, do not wait for symptoms. Contact your obstetrician or go to labor and delivery immediately. The medication choices and the speed of treatment differ from what is appropriate for non-pregnant adults, and delay carries real risk.
When 173 Keeps Coming Back
If your blood pressure consistently reads in the 170s despite taking medication as prescribed, you may have what is called resistant hypertension. Before accepting that label, there are several things to rule out. Poor medication adherence is the most common explanation: even small lapses, like forgetting a dose twice a week, can prevent adequate control. Interactions with other drugs, including anti-inflammatory painkillers and certain supplements, can blunt the effect of blood pressure medication. And pseudo-resistance from white-coat effect is surprisingly common, particularly in older adults.20PubMed Central. Hypertension in frail older adults: current perspectives Ambulatory monitoring is the best way to separate true resistance from artificially elevated office readings.6PubMed Central. When and how to use ambulatory blood pressure monitoring and home blood pressure monitoring for managing hypertension
If resistance is confirmed, investigation for secondary causes becomes worthwhile. Primary aldosteronism, where the adrenal glands overproduce a hormone that causes sodium retention, is the most common secondary cause and is more frequent than once thought. Other possibilities include kidney artery narrowing, thyroid disorders, and obstructive sleep apnea, which raises blood pressure through repeated nighttime oxygen drops and stress hormone surges.9PubMed. Diagnostic and Therapeutic Approach to the Major Secondary Causes of Arterial Hypertension in Young Adults: A Narrative Review Identifying and treating these underlying conditions can sometimes bring blood pressure down when additional medications cannot.