How the tools calculate

Last updated: 28 October 2026

The calculators on this site are ports of the functions the Aurora app uses (MOHCalculator and MIDASScorer in AuroraCore). Both share a set of test cases, so the same numbers give the same result on the site and in the app.

Medication days counter

What is counted

Days, not doses. Several doses of one medicine on one day count as one day.
Acute (as-needed) medicine only. Preventive medicine taken daily is not counted.
The last 30 days. The app uses a rolling window that ends today.

Limits

Type of medicine	Days per month
Triptans	10
NSAIDs and aspirin	15
Acetaminophen (paracetamol)	15
Combination painkillers	10
Opioids	10
Ergotamines	10

The limits are those of ICHD-3 section 8.2, medication-overuse headache. Gepants (rimegepant, ubrogepant, zavegepant) and lasmiditan are not counted against a limit because ICHD-3 (2018) does not list them; this does not mean any frequency is safe. A 2021 American Headache Society consensus statement found that frequent use of rimegepant or ubrogepant does not appear to lead to medication-overuse headache; it did not cover zavegepant and noted possible overuse with lasmiditan. The US prescribing information for lasmiditan includes a warning about medication-overuse headache. The counter shows a note about this.

Bands

Share of the limit	Result
Under 60%	Below the monthly limit
60% to under 80%	Approaching the limit
80% to under 100%	Close to the limit
100% or more	At or over the limit

More than one type of medicine

ICHD-3 section 8.2.6 covers overuse of several types of medicine when none of them is over its own limit. The counter then uses the number of days on which any counted medicine was taken. A day with two types counts once.

The rule applies only when two or more counted types were used and no single type is over its own limit.
Acetaminophen and NSAIDs (including aspirin) together: 15 days. ICHD-3 section 8.2.3 regards all non-opioid painkillers as a single class and counts their days cumulatively against the 15-day limit.
Any combination that includes another type: 10 days, ICHD-3 section 8.2.6.

What the result is not

ICHD-3 criteria for medication-overuse headache require overuse for more than three months and headache on 15 or more days a month in a person with a pre-existing headache disorder. One month at or over the limit is a reason to discuss the count with a doctor, not a diagnosis. In the app, the label “meets criteria” requires four consecutive monthly checks at or over the limit and 15 or more headache days in the current window.

MIDAS calculator

Five questions, each a number of days in the last 3 months.
Score = sum of the five answers.
Grade I: 0–5, grade II: 6–10, grade III: 11–20, grade IV: 21 or more.
Two further questions, headache days and average pain, are recorded but not scored.
Days in questions 1 and 2 together cannot exceed 90, nor in questions 3 and 4, because the second question of each pair excludes the days of the first. The score therefore ranges from 0 to 270.