Symptom, Sign and Side Effect Terms

Symptoms people experience, clinical signs, and unwanted effects of illness or treatment. Browse definitions and meanings below.

101 terms

What is the difference between a symptom and a sign?

A symptom is something the person experiences and reports: pain, nausea, dizziness, fatigue. A sign is something another person can observe or measure: a rash, a temperature, a heart murmur, swelling. Pain is a symptom because nobody else can see it. A fever is a sign because a thermometer records it.

The distinction is not academic. A condition that produces symptoms without signs can be hard to demonstrate, and one that produces signs without symptoms can advance unnoticed. A side effect is a third category again: an effect of a treatment rather than of the illness, and it can present as either a symptom or a sign.

Terms in this topic

Alphabetical order
  • Pain with a clear beginning and a clear cause, which fades as the injury behind it heals.

  • A finding rather than a diagnosis: something occupying the space beside the womb, which could be any of a dozen things.

  • Whether an unwanted development counts as an effect or merely an event turns on one question: did the treatment cause it?

  • New restlessness in an older adult points more often to a physical illness than to a psychiatric one, which is where the search starts.

  • The pattern of loss, and whether the follicle survives, matter more than the amount, because one determines whether hair can return.

  • Chest discomfort that arrives on exertion and leaves at rest is the heart complaining about a supply line that has narrowed.

  • A description of conduct that disregards other people's rights, and not, in clinical use, a word for being shy or private.

  • A useful alarm system that has become a problem when it fires without a threat, or keeps firing after one has passed.

  • aphasia

    / uh-FAY-zhuh /

    An acquired impairment in producing or understanding language.

  • apnea

    / AP-nee-uh /

    A temporary cessation of breathing.

  • A missing letter rather than a different symptom: the same joint pain, spelled the way it is often typed and rarely corrected.

  • How many joints hurt, whether they match on both sides, and how long morning stiffness lasts sort the causes faster than the pain itself.

  • Unevenness between two parts that should match, a finding whose weight depends entirely on where in the body it appears.

  • Feeling nothing is not the same as nothing happening, which is the entire reason screening programs exist.

  • Ataxia is impaired coordination of voluntary movement, causing unsteady walking, clumsy limb motion, or imprecise gestures despite normal muscle strength.

  • Walking that has lost its coordination, wide and lurching, as though the legs were no longer taking instruction accurately.

  • Short term relief that teaches itself: stepping away eases the fear at once, and that immediate ease keeps the pattern running.

  • A slow pulse is a problem only when it fails to deliver enough blood; in a trained athlete the same reading is fitness.

  • Intense increases in pain that occur with rapid onset even when pain-control medication is being used.

  • The reversible half of an asthma attack: muscle squeezing airways shut, distinct from the swelling and mucus that clear far more slowly.

For learning, not diagnosis. This glossary provides general educational information and is not a substitute for advice from a qualified healthcare professional. If you may be experiencing a medical emergency, contact local emergency services.