What is the difference between Symptom and Sign?

In Medicine a Symptom is generally subjective what patient feels or what patient complains of for example Tiredness, Headache, Feverish, Stomach ache etc.,

Where as a Sign is Objective evidence of a disease, such as blood in stool, a skin rash- it can be identified by the Doctor, Nurse, Family members and by the patient himself.

Lay man often feel 'symptom' is what he complains of and will understand the term 'sign' if used by a doctor as having the same meaning as symptom.

Few examples of Symptoms and sign

Patient complains of Feverish which is a symptom

Doctor identifies raise in body temperature by Thermometer which is a sign

Patient notices skin rash and complains of having skin rash to Doctor, in this case skin rash is both a sign and symptom.

Patient cannot complain of High blood sugar or High blood pressure it can only be identified by test so these are always a sign.

Diseases are many symptoms are few, many diseases or infections have symptoms in common however may differ in the onset, pattern, frequency e.t.c

A History of Symptoms presented by a patient becomes very important for a doctor to diagnose patient’s condition and manage his case.

In next post we shall understand in detail about History taking.