Why is only my bottom blood pressure number high?
The bottom number, diastolic, is the pressure between beats. Isolated high diastolic readings are more common in younger adults and often track with stress, alcohol, salt and weight.
It still counts. Sustained diastolic readings of 90 or above carry risk and respond to the same treatment as any high blood pressure.
Check your cuff fits and your arm is supported at heart height, because poor technique inflates the bottom number first. Then bring a week of readings to your doctor.
See a doctor promptly if
- A reading of 180/120 mmHg or higher with chest pain, breathlessness, weakness on one side, slurred speech, confusion or sudden visual change. This is an emergency
- Blood pressure of 140/90 mmHg or higher in pregnancy, especially with headache, upper abdominal pain, visual disturbance or sudden swelling
- A repeated reading of 180/120 mmHg or higher even without symptoms. This needs same-day medical assessment
- New severe headache, nosebleeds that will not stop, or breathlessness lying flat alongside high readings
- Blood in the urine, or a sharp fall in how much urine you pass, together with high readings
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Answered by the AskDoc Medical Team · Medically reviewed under our Medical Director, MBBS · How we review
If you are buying a monitor
Get an upper-arm cuff, not a wrist one, from a validated brand like Omron. Expect $30 to $60. Check the cuff size fits your arm; a too-small cuff reads high.
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Have your own result?
Send the report. A doctor explains every value in writing within 3 days.
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Health education, not medical advice.