How to keep a symptom diary

Almost everyone has tried to remember, in a waiting room, exactly when something started. It is genuinely hard. The days blur, the bad night moves around in your memory, and by the time you are asked you are guessing. A symptom diary is simply the fix for that — a few lines a day so the answer is already written down.

Start with the date it began

The single most useful thing in any record is when it started. Everything else — better, worse, the same — only means something against that first day. If you are already a few days in, note your best guess and say that it is one.

Write down what you notice, in your own words

You do not need medical language. “Throat raw, hard to swallow” is more use than a term you half-remember. Note the main things you are aware of, and whether each one seems to be easing or building.

Keep it to the things you would actually mention. A diary that lists everything is one you stop keeping by Thursday.

A diary kept lightly for three weeks beats a detailed one abandoned on day four.

Note what you have taken, and when

What you took and the time you took it. This is the part people most often cannot recall and most often get asked. If someone else gave it — a partner, a parent — note that too.

Keep half an eye on the ordinary things

Sleeping, eating, drinking, whether you managed the day. These sound too plain to be worth writing down and they are often the clearest signal of all. A week where you slept badly every night says something a list of symptoms does not.

Once a day is enough

The same time each day, at the end of it, when you can see the whole day. Not every hour. A diary kept lightly for three weeks beats a detailed one abandoned on day four.

And if you miss a day, leave the gap. A gap is information too — most people do not write anything down on the days they feel fine.

What it is for

Two things. It gives you a picture across weeks that you cannot hold in your head, and it gives you something to hand over. Ten seconds of reading tells a doctor or practitioner what ten minutes of recalling would not.