High diastolic blood pressure is a type of hypertension. Doctors do not know precisely why it happens, but obesity, high triglyceride levels, smoking, and alcohol may contribute.

Doctors describe blood pressure using two measures: systolic and diastolic pressure. They present a reading with the systolic number appearing above the diastolic. Systolic measures the pressure during the heart’s contraction, while diastolic is the pressure in the period between heartbeats.

Many people put a lot of emphasis on the systolic number. However, studies show that each increase of 10 millimeters of mercury (mm Hg) in diastolic pressure in people ages 40–89 years doubles the risk of heart disease or stroke.

Doctors define isolated diastolic hypertension (IDH), or high diastolic blood pressure, as above 80 mm Hg in individuals with normal systolic blood pressure.

This article discusses the common causes of high diastolic blood pressure and its associated risks, how to help prevent high blood pressure, and the treatment options.

If an individual has hypertension, they have an increase in both systolic and diastolic blood pressure.

However, if an individual has elevated diastolic blood pressure, they have IDH. Doctors classify stage 1 IDH as a diastolic blood pressure of 80–89 mm Hg diastolic blood pressure. They classify stage 2 IDH as diastolic blood pressure above 90 mm Hg.

Learn more about blood pressure readings.

IDH is uncommon and accounts for less than 20% of hypertension cases.

Doctors do not understand why an individual may develop diastolic hypertension. They suggest it may result from the narrowing of arterioles due to hormones in the body.

Common causes of IDH include:

However, some potential and preventable causes of IDH also include the following:

Obesity

Doctors usually associate hypertension with obesity. However, they also link having overweight or obesity to IDH.

To reduce the risk of IDH, a person can take steps to reach a moderate weight through diet and exercise.

A doctor can suggest alternative weight management options if a person finds it challenging to make dietary changes or increase physical activity.

Alcohol consumption

Some studies show that alcohol consumption contributes to IDH.

To help prevent high blood pressure, the AHA recommends that males consume no more than two alcoholic drinks per day and females consume no more than one alcoholic drink per day.

The AHA states that one drink is either:

  • 12 ounces (oz) of beer
  • 4 oz of wine
  • 1.5 oz of 80-proof spirits
  • 1 oz of 100-proof spirits

Learn more about ways to reduce alcohol consumption.

Research associates smoking with IDH. A study in China found that among individuals ages 90 years and over, current or previous heavy smoking increased diastolic blood pressure.

Learn more about ways to give up smoking.

Elevated triglycerides, or blood fats, are another potential cause of IDH that doctors also link to other health risks.

Almost 1 in 3 Americans have high triglycerides. When these blood fats are high, they lower “good” HDL cholesterol. If individuals have elevated blood triglycerides and high “bad” LDL cholesterol, this increases their risk of heart disease and stroke.

People can lower their blood triglycerides by making dietary changes. For example, following a Mediterranean-style diet rich in oily fish, fruit, vegetables, and whole grains may help reduce blood triglycerides and IDH.

There are certain risk factors for high diastolic blood pressure that a person cannot control.

They include:

  • Age: Diastolic hypertension is common in people under 50 years of age. IDH is rare in older adults.
  • Family history: Having family members with hypertension increases an individual’s risk of IDH.
  • Cardiovascular events: If an individual has experienced an incident that damaged the heart muscle, this increases their risk of IDH.
  • Diabetes: People with diabetes and raised blood sugar levels may be more likely to develop IDH.
  • Hypothyroidism: Around 30% of individuals with low thyroid hormone levels have IDH.
  • Kidney disease: Individuals with chronic kidney disease may also have IDH.
  • Biological sex: In a large 2019 study of almost 2.5 million participants, researchers found that the prevalence of IDH was significantly higher among males, at 4.5% of the overall population, compared with females at 2.2%.

If an individual has normal systolic blood pressure, lowering the diastolic blood pressure can affect the brain’s blood flow regulation, leading to a stroke.

According to a study, researchers associated IDH with an increased risk of subsequent cardiovascular events.

IDH increases an individual’s risk of various health conditions, including:

Reducing diastolic blood pressure may cause heart problems, particularly in young individuals with normal systolic blood pressure. Therefore, in this group, doctors may opt not to treat IDH.

IDH is uncommon in older adults, but doctors may choose a nonsurgical approach if they diagnose IDH. The best approach is for doctors to treat older adults depending on their underlying cardiovascular disease.

Medication options for IDH include:

Doctors may also recommend that individuals make lifestyle changes to reduce their IDH, including:

  • reducing alcohol consumption
  • maintaining a moderate weight
  • exercising daily or most days
  • eating a balanced diet
  • avoiding tobacco
  • monitoring blood pressure levels at home

If someone monitors their blood pressure at home and does not see lower readings despite implementing lifestyle changes, they should contact a medical professional. Doctors can help determine the underlying cause of their high blood pressure.

A person should seek immediate medical attention if they have two readings of 180/120 mm Hg or higher within 5 minutes, especially if they are experiencing a headache or nosebleed.

Below are frequently asked questions regarding blood pressure.

What does it mean if my diastolic blood pressure is high?

High diastolic blood pressure increases a person’s heart disease and stroke risk. It means an increase in pressure in the cardiovascular system between heartbeats, which can impair oxygen delivery to the heart muscles.

Should I worry if my diastolic is high?

Doctors do not associate increased diastolic blood pressure with cardiovascular events in younger individuals.

However, increases in diastolic pressure in those ages 40–89 years raise the risk of heart disease and stroke. Therefore, individuals should work with a doctor to find suitable treatment options and improve their outlook.

What is the best way to lower diastolic blood pressure?

Doctors can recommend lifestyle interventions, medication, and surgery if necessary to treat high diastolic blood pressure. It is best to consult a medical professional if a person believes their blood pressure is too high.

Is 90 diastolic too high?

Any diastolic blood pressure reading over 80 mm Hg is too high.

Diastolic pressure is the bottom number of a blood pressure reading.

IDH occurs if someone has elevated diastolic blood pressure, increasing a person’s risk of heart disease and stroke.

Smoking, consuming alcohol, obesity, and high blood fat may lead to IDH. Additionally, certain groups of people have an increased risk of IDH, including younger males and people with diabetes or previous cardiovascular events.

High diastolic blood pressure is rare in younger people, and doctors may not treat this group. They may recommend treatment in older individuals based on their current heart health status.

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