Signs and symptoms

Signs and symptoms are two words that doctors use to describe how a medical problem causes changes in a person's body.
Signs.
A sign is a change in the body that can be heard, seen, felt, or smelled by a doctor. A sign may also be shown on medical tests like X-rays or blood tests. For example:
Symptoms.
A symptom is a change in the body that cannot be seen, heard, felt, or smelled by a doctor. It also cannot be shown on medical tests. A symptom is something that only the person having the symptom can see, hear, feel, or smell. For example:
Signs and symptoms often happen together.
Often, medical problems cause both signs and symptoms. For example: