"Indications" in medicine may have two different definitions, which both take into account the idea that indication is another word for sign or reason. In the first definition, people with certain conditions display indications or signs that they should be treated in a specific way, either by being given some form of medication, or by undergoing specific therapies like surgeries. Symptoms can also be indications of diseases, and doctors can use these symptoms as a method of diagnosing disease or even determining the death of a patient based on the signs or symptoms present.
There are many ways to determine what symptoms a person has that may indicate or justify a certain treatment. Doctors may do a physical examination or simply listen to a patient’s account of symptoms to determine the best course of action. If this doesn’t provide enough information, there are ways to more specifically decide the right thing to do. These could include evaluating blood or tissue to see if there are elements there that can be treated.
Alternately, things like x-rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI) are possible interventions that may help narrow down the best treatment. Calling for additional tests is usually indicated by a doctor’s first evaluation of symptoms. For example, a patient at a doctor’s office who has an extreme sore throat and high fever presents with indications that a strep test should be performed. If this test is positive, this is indication to treat the condition with antibiotics, and there are certain antibiotics indicated in best treatment of strep.
There can also be medications or treatments contraindicated by a patient’s symptoms or previous medical history. The doctor treating for strep throat might be inclined to give a medicine like penicillin. If a patient has an allergy to this medicine, this would be a contraindication, or absolutely not recommended. Since penicillin is contraindicated, doctors would look for another antibiotic that would effectively treat strep but wouldn’t be likely to result in a negative or allergic reaction.
Symptoms can indicate treatment or they can be indications of disease, which might then be used to determine treatment. The symptoms of sore throat and high fever are indications of strep throat, which help physicians decide to test for confirmation of the illness. Wheezing and inability to catch the breath could possibly indicate asthma. Doctors have to narrow it down, since there are many diseases with very similar symptoms. Having as many specific indications possible is useful, but more advanced testing is often needed to make a determination on diagnosis, and on treatment.
Patients can determine some indications too. On most package inserts from medications, there is a list of indicated uses. Sometimes people will use things for off-label purposes, but many times a medication fits within the specific indicated use. If people don't see their condition as an indication to use the drug, they could discuss the matter with physicians. It should be noted that off-label use is pretty common.