> ## Documentation Index > Fetch the complete documentation index at: https://docs.sonohealth.com/llms.txt > Use this file to discover all available pages before exploring further. # Monitoring Your Oxygen During a Respiratory Illness at Home > How to use a pulse oximeter while recovering from a cold, flu, COVID, or chest infection, what trends to watch, and when a low reading means seek care. When a respiratory illness has you coughing and short of breath, a fingertip pulse oximeter can offer reassurance and an early warning sign. The key is to track trends and pair the number with how you actually feel. A pulse oximeter does not diagnose or treat illness. Severe breathlessness, chest pain, bluish lips, confusion, or trouble staying awake is an emergency — call 911 even if the reading looks borderline. ## 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%](/pulse-oximeter/normal-oxygen-levels). 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](/pulse-oximeter/copd-asthma-monitoring) 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](/pulse-oximeter/pulse-oximeter-accuracy-guide). ## 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](/pulse-oximeter/normal-oxygen-levels) · [Oximetry With COPD or Asthma](/pulse-oximeter/copd-asthma-monitoring) · [Accuracy Guide](/pulse-oximeter/pulse-oximeter-accuracy-guide) · [How a Pulse Oximeter Works](/pulse-oximeter/how-a-pulse-oximeter-works)