Low diastolic blood pressure is when the diastolic blood pressure falls below 60 mm Hg while the systolic blood pressure remains at a normal level. Low diastolic blood pressure decreases blood flow to the heart, which can cause the heart to weaken over time and potentially lead to heart failure. A 2016 study found that a diastolic blood pressure below 60 mm Hg is dangerous and people with this level are 50 percent more likely to have heart damage. This is compared with those who have a low diastolic pressure level between 80 and 89 mm Hg. The same study found that those with low diastolic blood pressure were 49 percent more likely to develop heart disease.

Symptoms of heart failure include shortness of breath, persistent cough, swelling in the lower body, tiredness, nausea, confusion, and palpitations. Anyone experiencing more than one of these symptoms should seek immediate medical attention.

It is important to note that what is considered low blood pressure for one person might be okay for someone else. Most healthcare providers consider blood pressure to be too low only if it causes symptoms. Occasional minor dizziness or lightheadedness can be caused by many things, such as spending too much time in the sun or in a hot tub.

In summary, a diastolic blood pressure below 60 mm Hg is considered dangerously low and can lead to heart damage and heart disease. Anyone experiencing symptoms of heart failure should seek immediate medical attention.