What should you know about a USB spirometer?

The device records how much air you breathe out and how quickly you can blow. USB connectivity may let software display or store the result. A reading can be affected by posture, effort, a poor seal around the mouthpiece, coughing, recent activity, or the device’s calibration. One result cannot establish whether symptoms come from asthma, chronic obstructive lung disease, infection, anxiety, or another cause.

A low or changing result may be useful information, but it is not a substitute for an examination. Formal [Spirometry](/treatments/diagnostics-and-screening/spirometry/) follows a coached method and may include repeated efforts and medicine-related comparisons.

Follow the device instructions and your clinician’s plan. Sit or stand as advised, create a firm seal, take the required breath, and repeat only as directed. Record the date, symptoms, and relevant medicine use with the reading. Do not alter prescribed inhalers because of a single home result, and do not share mouthpieces.

If the numbers are unexpectedly low, inconsistent, or difficult to obtain, arrange a clinical review. Bring the device or its saved readings to an appointment so technique and equipment can be checked.

Get urgent help for severe breathlessness, blue or grey lips, inability to speak in full sentences, fainting, confusion, or rapidly worsening wheezing. A concerning spirometer result should never delay emergency care. Contact a clinician promptly for new breathlessness, chest pain, coughing blood, or a clear decline from your usual breathing.

Ask which measurement matters for you, how often to test, what technique to use, what change should prompt contact, and whether formal spirometry or another assessment is needed. Clarify whether your medicines should be taken before testing.