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High blood pressure rarely announces itself — most people feel completely normal even when their numbers are elevated. That’s exactly why it’s dangerous, and why home monitoring matters. This guide explains the stages, the rare warning signs, and the line between “call your doctor” and “call 911.”
A blood pressure reading at or above 180/120 mm Hg is a hypertensive crisis. If it comes with chest pain, shortness of breath, weakness or numbness, trouble speaking, vision changes, or a severe headache, call 911 immediately — these can be signs of a heart attack or stroke.

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What counts as high blood pressure?

Using American Heart Association categories, Stage 1 hypertension is 130–139 systolic or 80–89 diastolic, and Stage 2 is 140/90 or higher. A reading above 180/120 is a hypertensive crisis. Because readings fluctuate, hypertension is diagnosed from multiple readings over time — not one number. See the full category breakdown.

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Does high blood pressure have symptoms?

Usually not. The common belief that high blood pressure causes headaches, flushing, or nosebleeds is largely a myth at typical elevated levels — most people have no symptoms at all. This is why it’s called the “silent killer” and why routine home monitoring is so valuable for catching it.

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When to contact your doctor

Reach out (non-urgently) if your home readings are consistently in the Stage 1 or Stage 2 range, if you notice an irregular-heartbeat flag on your monitor, or if your numbers change suddenly. Bring your log so your clinician can see the pattern. They may confirm a diagnosis, adjust treatment, or recommend lifestyle changes.

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When it’s an emergency

If you get a reading at or above 180/120:
  • Without symptoms: rest five minutes and re-measure. If it stays that high, contact your doctor right away.
  • With symptoms (chest pain, breathlessness, weakness/numbness, trouble speaking, vision changes, severe headache): call 911 — do not wait or drive yourself.

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The bottom line

A home monitor helps you and your doctor catch and manage high blood pressure early, but it doesn’t treat it. Lifestyle steps and any prescribed medication do the work — and you should never stop medication on your own. SonoHealth’s BPpro and BPMAX make consistent monitoring easy; see them at SonoHealth.com.
Related: Normal Blood Pressure Ranges · Home Monitoring Guide · How to Measure at Home · Heart Palpitations