Why monitor oxygen when I’m sick?
Some respiratory illnesses can lower blood oxygen, sometimes before you feel dramatically worse. Checking your SpO2 a few times a day can help you notice a downward trend early and know when it’s time to call a clinician — turning a vague “am I getting worse?” into something more concrete.What’s a normal reading, and what’s low?
For most people a normal SpO2 is 95–100%. Readings drifting into the low 90s deserve attention and a recheck with good technique, and readings below about 90% generally warrant prompt medical contact. If you have a lung condition like COPD, your personalized target may differ — follow your doctor’s guidance.Track trends, not single numbers
One reading is a snapshot. Note your SpO2 and pulse at consistent times (for example, morning and evening), at rest, and keep a short log. A steady, gentle trend downward is more meaningful than a single odd value, which may just be cold hands or motion.Check your reading quality
Warm your hands, remove nail polish, sit still, and let the number settle. If a low reading appears but you feel completely fine, re-check before reacting. Conversely, if you feel breathless, get care even if the number looks normal.When to seek care
Contact a clinician for readings consistently below your normal range or a clear downward trend, and seek emergency help for severe breathlessness or the warning signs above. A pulse oximeter supports decisions — it doesn’t replace medical judgment.Related: Normal Oxygen Levels · Oximetry With COPD or Asthma · Accuracy Guide · How a Pulse Oximeter Works