Fifteen seconds a day beats any test you will be sent for.

THE ONE PIECE OF HOMEWORK

To keep a headache diary, record five things every day for two weeks: the date, whether you had any head pain, how bad it was in three levels (mild, interfered with the day, could not function), what you took and how many doses, and roughly what time it started.

Fifteen seconds a day for two weeks produces more useful information than any test you will be sent for. Here is exactly what to record and, more importantly, what to leave out.

The five fields

• Date.
• Any head pain at all? Yes or no. Including days you treated early and it never fully developed — those count.
• How bad, in three levels. Mild / interfered with the day / could not function. Not a number out of ten.
• What you took, and how many doses.
• Clock time it started, roughly. Punctuality is diagnostic in several disorders.

That is the whole thing. Two optional extras earn their place: bedtime and wake time, and anything unusual the day before — a missed meal, a long drive, alcohol, a shift change.

Why three levels beat a ten-point scale

A number out of ten is unreliable between people and unreliable within one person over time. Function is not. “Could not work” means the same thing in January and in June, and it is the thing treatment is actually aiming at. Clinics that ask for a 0–10 score are collecting a noisier signal than the one you could give them.

The two counting errors that hide the diagnosis

The first is excluding treated days. People record only the days the headache won, so a genuine 16-day-a-month pattern gets reported as six. That single error is why chronic migraine goes unrecognized for years, because the threshold that unlocks specific treatments is a day count.

The second is thinking in bad days rather than dosing days for medication. The question is not how much you took on the worst day; it is how many separate days you took anything. Past ten days a month of combination products or triptans, the treatment starts sustaining the pattern. Why that threshold matters.

What not to record

Do not track the barometer, the moon, or a long list of suspected trigger foods. Trigger hunting produces false associations at a high rate — you will find a pattern in noise because that is what humans do — and it converts the diary into a source of anxiety and dietary restriction that does not survive contact with evidence. Frequency and medication days are the two numbers that change decisions. Everything else is optional.

Paper or an app?

Whichever you will actually complete. Paper on the fridge beats an app you stop opening on day four. Completion rate is the only quality metric that matters here.

Frequently asked questions

How long do I need to keep it?

Two weeks is enough to be useful and to be worth an appointment. Two cycles if you are tracking a menstrual pattern — why.

What counts as a headache day?

Any day with head pain, including ones you treated early. Excluding treated days is the single most common error and it hides the diagnosis.

Should I track food triggers?

Generally no, unless something is glaringly reproducible. Trigger hunting mostly generates false positives and unnecessary restriction.

What if my pattern is obvious already?

Write it down anyway. An obvious pattern stated from memory and the same pattern shown in dated rows are treated very differently in a clinic room, fairly or not.

Can a headache diary show which type of headache I have?

It narrows the field quickly, and the start-time column does most of the work. Attacks that arrive at the same hour, often in the small hours, and come in bouts point toward cluster headache; attacks that bunch in the days around a period point toward menstrual migraine; a count that reaches fifteen days a month changes the category to chronic. The diary does not make the diagnosis by itself, the history and the neck examination do, but it turns a guess into a short list. Learn more: which headaches keep time, and why.

What the diary unlocks

• The frequency thresholds
• The overuse threshold
• The chronic migraine category
• What else to bring
• How it gets used in the room