Medication overuse headache (MOH) is the paradoxical condition where taking acute migraine medications too often transforms episodic migraine into chronic migraine. It’s defined in ICHD-3 as a distinct diagnosis, and it’s one of the most important patient-safety topics in headache care. MOH affects roughly 1–2 percent of the general population and a much higher fraction of patients in tertiary headache clinics.
The diagnosis exists because the pattern is so reliable: in patients with frequent acute medication use, withdrawing the medication typically reduces headache frequency over weeks to months. The relationship is not coincidence.
The overuse thresholds
ICHD-3 defines MOH by medication-class-specific thresholds, all measured as days per month for at least 3 consecutive months:
| Medication class | Threshold |
|---|---|
| Triptans | ≥ 10 days/month |
| Ergot alkaloids | ≥ 10 days/month |
| Opioids | ≥ 10 days/month |
| Combination analgesics (e.g., Excedrin) | ≥ 10 days/month |
| Simple analgesics (ibuprofen, acetaminophen, aspirin alone) | ≥ 15 days/month |
| Multiple classes combined | ≥ 10 days/month total |
| CGRP gepants | not currently associated with MOH |
A patient taking sumatriptan on 12 days/month for 4 months meets the criteria. So does a patient using only ibuprofen on 16 days/month for 4 months — even though they might think “it’s just ibuprofen, it’s harmless”.
Why this happens — mechanisms
The biology of MOH is incompletely understood, but the leading hypotheses include:
- Central sensitisation — frequent acute medication may paradoxically lower the migraine threshold over time, making attacks more likely.
- Receptor adaptation — triptan receptors (5-HT1B/1D) may become desensitised with frequent stimulation.
- Behavioural reinforcement — the immediate relief from acute medication creates a learning loop that increases consumption.
What’s clinically established is the reversibility: in most patients, withdrawing the overused medication produces a temporary worsening (1–4 weeks) followed by substantial improvement, often back to the patient’s prior episodic pattern.
The clinical course of MOH
The typical trajectory:
- Patient has episodic migraine, takes acute medications when attacks happen.
- Attack frequency increases (for any reason — life stress, hormonal changes, sleep disruption).
- Acute medication use rises in response.
- Above the overuse threshold for 3+ months, headache frequency continues to rise.
- Eventually, patient has near-daily headache and frequent acute medication use, with the medication providing diminishing benefit.
The trap is that to the patient, this looks like “my migraine is getting worse, I need more medication”. The clinical reality is often the reverse: the medication is contributing to the worsening.
How MOH is treated
The mainstay is withdrawal of the overused medication, with the specifics depending on the class:
- Simple analgesics, triptans, gepants: abrupt withdrawal is typically safe.
- Opioids, butalbital-containing medications, benzodiazepines: taper is required to avoid withdrawal syndromes.
- Bridge therapy during withdrawal: a different class of medication (sometimes prednisone, sometimes long-acting NSAIDs) helps manage the rebound week.
- Preventive medication started during withdrawal: addresses the underlying migraine pattern so the patient doesn’t recycle back into overuse.
This is not a process to attempt without medical supervision. The withdrawal period is uncomfortable and the management of bridge and preventive therapy is genuinely complex.
How Hermly handles MOH risk
Hermly is not a prescriber, but it can make the data visible:
- Medication frequency tracking — every medication you log (whether via Live Activity, the Action Button, or the in-app attack flow) counts toward the rolling 30-day window.
- Monthly report surfaces frequency — the doctor report includes a count of acute medication days per month.
- Safety nudge — if your 30-day attack count or medication count approaches the published MOH threshold, the monthly report surfaces it as a “topic worth discussing with your doctor” rather than as an alarm.
What Hermly does not do:
- Recommend that you stop or reduce a medication.
- Push notifications about medication use.
- Auto-detect MOH (it’s a clinical diagnosis that needs medical assessment).
If you suspect MOH may be developing — increasing acute medication use, increasing headache frequency despite using medications — the right move is to bring your data (Hermly’s monthly report or otherwise) to a neurologist or headache specialist who can evaluate the picture properly.
The harder truth
MOH is partially preventable through prescribing and patient education, but it’s also a side effect of having effective acute medications. When you have a triptan that works, the temptation to use it is real and rational. The thresholds exist because the data showed that beyond a certain frequency, the medication that helps individual attacks contributes to making attacks more frequent overall.
The way out is usually not “use less acute medication and suffer more attacks” but rather “address the underlying frequency with prevention” — which is why most MOH treatment plans involve starting a preventive medication during the withdrawal phase.