Diagnosis means deciding what is making someone unwell or sick and naming that disease. Mostly, members of the medical profession or para-medics can make diagnoses. Self-diagnosis means deciding yourself what's wrong with you, and naming the disease. To start, you need to have a symptom or two. Most people start looking stuff up about diseases and diagnosis when they have a symptom. A symptom is something that's wrong with you like a cough, or a pain somewhere, or stiffness, or hoarseness, or blurred vision, or dizziness. These are all symptoms. Very often, a couple of them occur together.

'What's wrong with me?' you ask. Then you go to the doctor and ask the doctor, 'What's wrong with me?' The doctor examines you, or sends you out for tests (like x-rays or blood tests), weighs you, measures you, asks you questions about your life, looks at your records, and then makes a diagnosis. Doctors do this with a certain amount of confidence because they have training and experience. That means they have studied diseases and their symptoms, can compare what they see with normal or non-diseased cases, and they have seen all this before.

The diagnosis a doctor makes is usually followed by an attempt to treat the illness or condition either by medication, a change of diet (what you eat) or a change in behaviours (what you do)... or all three. Or you can be referred to an expert in the field, called a specialist. A specialist can then confirm and check everything the doctor has reported, can either change the diagnosis, agree or disagree, and decide on a course of action. One course of action could be surgical intervention (an operation).

When you get a symptom and decide to skip all the doctor bit and decide for yourself, it means you run a number of dangers.

Let's say you have a cough, a rash on your ankle and you feel dizzy when you stand up after lying down. That's three symptoms. Gee, you are worried, so you go online and look these symptoms up. They are three very common symptoms and often occur together. They occur in a number of diseases - some of them rather strange and uncommon.

One of the descriptions of diseases is rather similar to the way you are feeling. Aha, you think - that's what I have! Then you read about the disease and are terrified out of your mind, because it's something you never thought you could get. In fact, you had never heard of it before today.

You go about for a week with a sense of disquiet. You don't want to tell anyone because it's really serious and they might worry. You also don't really want to check with a doctor for two reasons: one, you already know what you have, and two: he might tell you worse things like you are going to lose a limb or die soon. Or that you have to take really expensive medicine. Or have an operation!

You worry for a month until someone notices the rash on your ankle and tells you to stop eating strawberries because they are giving you hives, and your cough's gone. What happened to the disease the website said was pretty much close to terminal (life threatening)?

Have you worried for nothing? Or are you still sick? Should you take that cure you saw advertised that pretty much heals everything from sunburn to cancer? It was only $29.95 plus postage.

You have painted yourself into a corner and only a dose of sense will get you out.

Here's what you have done.

You have found a disease that fits the symptoms.

Without training or experience, you have decided what's wrong with you and named that disease as yours.

With nothing and no one to compare your three symptoms with, you have made a decision that could be wrong or right, but you decided it's right.

You have neither measured, weighed or examined yourself for all the things doctors are trained to check before they make a pronouncement. You have not compared your present state to other states you have been in, or similar states others have been in... sick or healthy.

You have not undergone any tests.

You have made decisions you are neither trained nor paid to do. Even doctors rarely diagnose themselves, and they know they could probably guess right.

So this is how not to do it. Do not feel a symptom or two and rush straight online to find out what's wrong with you. Do not match up your symptoms with a disease, decide that's it, and call it yours. Do not self-prescribe over the counter medication or send off for some magical pills that can cure everything. Do not give up hope or tell yourself you do not need a doctor.

This is the easy way to get stressed, and it's a bit on the silly side.

Besides, although there are many well-informed sites and sites that are run by real doctors, you have no real way of knowing which sites are good, which sites are very well-intentioned but full of mistakes, which sites are copied off others, and which sites are merely pretending to be helpful while trying to sell you their snake-oil.

There is no real way to distinguish between good and bad diagnosis sites or good and bad symptom sorter sites. Anyone can set up a site and call themselves Doctor Doses.

Self-diagnosis should really be confined to being observant about how you are feeling, being exact in describing how you feel to a professional, and watching yourself to see if those symptoms change.

Consulting a doctor if symptoms persist is not only helpful advice you find printed on the back of over the counter medicines. It's actually common sense.