Signs and symptoms

A diagram of a human torso labelled with the most common symptoms of an acute HIV infection
Signs (including enlarged liver and spleen) and symptoms (including headache and vomiting) of acute HIV infection

Signs and symptoms (S/S) are diagnostic indications of an illness, injury, or condition. While signs are objective and externally observable, symptoms are a person's reported subjective experiences.

A sign, for example, can be an elevated or lower than normal temperature or blood pressure, or an abnormal finding showing on medical imaging. A symptom is something out of the ordinary that is experienced by an individual such as feeling feverish, a headache or other pains in the body. Symptoms can be a result of the immune system's response to an infection, the physical manifestation of an abnormal body condition, or the effect of a consumed substance. Symptoms, though often indicative of a disease process, are not always diagnostically relevant, and can be idiopathic in nature.