High diastolic blood pressure: causes and what to do

A high diastolic blood pressure reading means the bottom number, the pressure in your arteries between heartbeats, is elevated. Common contributors include age, family history, excess body weight, high sodium intake, alcohol, inactivity, poor sleep, and some medicines or health conditions. One reading cannot tell you the cause. Repeat it carefully, record several readings, and discuss a persistent pattern with your doctor. If a reading is 180/120 mmHg or higher with chest pain, shortness of breath, back pain, weakness, vision change, or trouble speaking, call 911.

When a high reading needs urgent attention

A high number by itself often causes no noticeable feeling, so do not use symptoms alone to judge your pressure. If your reading is 180/120 mmHg or higher, wait at least one minute and measure again. If it remains that high and you have chest pain, shortness of breath, back pain, numbness or weakness, vision change, or difficulty speaking, call 911. Those symptoms with a very high reading require emergency care. If the repeat is still that high but you have no symptoms, contact a healthcare professional promptly for instructions rather than trying to bring it down yourself.

A single unusual result can follow a rushed measurement, recent exercise, nicotine, caffeine, pain, or stress. Sit quietly and repeat it using a properly sized cuff. If repeated readings remain elevated, schedule a medical appointment even if you feel well. The hypertension stages guide explains how clinicians classify readings, and how to read a blood pressure reading covers the top and bottom numbers.

What the diastolic number tells you

The diastolic number measures pressure in the arteries while the heart relaxes between beats. The systolic, or top, number measures pressure when the heart contracts. Either number can be high. Under the 2017 ACC/AHA guideline, stage 1 hypertension includes a diastolic reading from 80 to 89 mmHg, and stage 2 includes 90 mmHg or higher; the category is based on whichever of the two numbers is in the higher category. A diagnosis is based on properly taken readings over time, not one result. The systolic versus diastolic explainer has more detail. Source: 2017 ACC/AHA guideline, PMID 29133356

When the bottom number is repeatedly high while the top number is below 130, clinicians may describe the pattern as isolated diastolic hypertension. The pattern needs context: age, medical history, and repeated measurements matter. It is different from the more common pattern in older adults where systolic pressure is high and diastolic pressure is lower. See high systolic with low diastolic pressure for that separate situation.

Diastolic blood pressure high causes

The short answer to “what causes diastolic blood pressure to be high?” is that several factors can contribute, and often there is no single identifiable cause. Blood pressure regulation involves blood vessels, kidneys, hormones, the nervous system, and the heart. A clinician may consider the following possibilities.

Possible contributor	Why it can matter	A useful next step
Age, family history, and weight	Risk tends to rise with age, and inherited traits and body weight can influence pressure	Review your overall risk with your clinician
High sodium intake and eating patterns	Sodium can affect pressure in some people; a diet low in produce and rich in processed foods may leave less room for heart-supportive foods	Track packaged and restaurant foods for a week
Alcohol, nicotine, and inactivity	These can affect cardiovascular health and readings; effects differ between people	Discuss realistic changes and support
Poor sleep or sleep apnea	Repeated sleep disruption and breathing pauses deserve attention as part of a blood pressure evaluation	Mention loud snoring, gasping, or daytime sleepiness
Medicines and substances	Some over-the-counter pain relievers, decongestants, stimulants, and other drugs may raise pressure	Bring a full medication and supplement list
Other health conditions	Kidney disease, diabetes, and hormone-related conditions can be relevant	Ask whether your history suggests further evaluation

These are possibilities, not a personal diagnosis. Many people with high blood pressure do not identify one clear cause. The guideline recommends clinicians review risk factors, medication use, and possible secondary causes when appropriate. Do not stop a prescription or change its timing based on a home reading. If you suspect a medicine is affecting your pressure, ask the prescriber or pharmacist to review it.

Why is my diastolic blood pressure high today?

A high result today may be temporary, especially if you measured right after walking, smoking, drinking coffee, having a stressful conversation, or rushing. A cuff that is too small, an unsupported arm, talking during the measurement, or crossing your legs can also make a reading less reliable. These factors do not prove that the pressure is normal; they mean it is worth repeating under consistent conditions.

For a useful home record, use a validated automatic upper-arm monitor and a cuff that fits. Avoid caffeine, smoking, and exercise for 30 minutes beforehand. Empty your bladder, sit quietly for five minutes with your back supported and feet flat, and rest your arm at heart level. Take two readings one minute apart, morning and evening, for several days unless your clinician advises otherwise. Record the time and anything unusual, then bring the monitor and log to your appointment. See how to take blood pressure at home or use the blood pressure checker.

Habits that can support healthier readings

Lifestyle changes can help, but they are not a substitute for an individualized care plan. Start with one or two changes you can maintain, then review the home trend with your clinician.

Build meals around minimally processed foods. The DASH research diet emphasized fruits, vegetables, and low-fat dairy, alongside lower saturated and total fat. In an eight-week controlled feeding trial of 459 adults, the combination diet lowered average diastolic pressure 3.0 mmHg more than the control diet. That study tested a complete eating pattern, not a single food or supplement. Consider beans, vegetables, fruit, whole grains, and unsalted nuts, while checking sodium on packaged foods. Source: DASH trial, PMID 9099655. Our DASH diet guide gives practical meal ideas.

Move regularly and work toward a comfortable weight. Physical activity and weight management are standard parts of blood pressure care in the ACC/AHA guideline. Choose activity that fits your health, such as walking, and build gradually. If you have heart disease, significant symptoms, or have been inactive, ask your doctor what level is appropriate.

Protect sleep and review possible sleep apnea. Tell your doctor if you snore loudly, wake gasping, or feel sleepy in the daytime. A clinician can decide whether evaluation is warranted. Read more about hypertension and sleep apnea and our sleep habits for men over 50.

Keep alcohol moderate and avoid tobacco. Alcohol and nicotine can affect cardiovascular health and readings. Discuss a practical plan with your care team, and avoid smoking or vaping just before a measurement.

Check medicines and supplements with a professional. Bring a list of prescriptions, cold products, pain relievers, energy products, and supplements. Some can affect pressure or interact with prescriptions. Do not discontinue prescribed medicine on your own; ask the prescriber about changes in your readings.

What about supplements?

Small studies of particular ingredients do not show that a supplement can manage high blood pressure, or that an ingredient in a blend will work like the studied preparation. For example, one six-week controlled trial in 65 adults who were not taking blood pressure medicines found hibiscus tea reduced systolic pressure compared with placebo, while the diastolic difference was not statistically significant. It was a tea study, not proof for capsules or for treating a high bottom number. Source: PMID 20018807

A crossover trial in 60 prehypertensive men found lower average daytime and 24-hour systolic and diastolic readings during a six-week period using a specified olive leaf extract. The product’s extract and measured compounds were defined; that result cannot establish an effect from a different formula with undisclosed amounts. Source: PMID 26951205

Our supplement scores are strict: they consider ingredient evidence, whether doses are disclosed and comparable to research, label transparency, and value. Cardio Shield has some relevant ingredient research, but six botanicals share a 570 mg blend, so individual amounts cannot be checked. It has no located clinical trial of the finished formula. Read our heart and circulation supplement comparison and Cardio Shield review for label details. Talk to your doctor before using supplements, especially with medications. Never replace or adjust prescribed treatment based on a supplement. Results vary.

Next step

Take a week of careful readings and bring the log, your monitor, and a complete medication and supplement list to your doctor. That gives you a more useful conversation about what may be raising your diastolic number and what to do next.

Frequently asked questions

What causes diastolic pressure to rise?

A repeated rise can reflect age, family history, body weight, sodium intake, inactivity, alcohol, sleep problems, medicines, or another health condition. A clinician can assess your pattern.

What causes diastolic blood pressure to be low?

A low bottom number can occur with dehydration, illness, medicines, or age-related artery changes. Meaning depends on the top number and your symptoms. Fainting or chest pain with low pressure needs urgent care. See low blood pressure in older adults.

Can stress make my diastolic reading high?

Stress or pain may coincide with a temporary increase, but one reading cannot establish the cause. Sit quietly, repeat the measurement correctly, and track readings over several days. Persistent elevation deserves a medical discussion.

Should I worry if only the bottom number is high?

Do not ignore repeated high diastolic readings, even if the systolic number looks acceptable. The higher category from either number matters under the 2017 ACC/AHA guideline. Record results and ask your clinician how they fit your health history.

When should I call 911 for high blood pressure?

Call 911 for a reading of 180/120 mmHg or higher together with chest pain, shortness of breath, back pain, numbness or weakness, vision change, or difficulty speaking. If the repeat reading remains that high without symptoms, contact a medical professional promptly for direction.

Results vary. Talk to your doctor, especially if you take medications. New or worsening symptoms deserve medical care.