Episodic vs chronic migraine
The distinction matters because it changes what you qualify for:
- Episodic migraine, fewer than 15 headache days a month.
- Chronic migraine, 15 or more headache days a month for at least 3 months, of which at least 8 days have migraine features.
Chronic migraine is what unlocks Botox under NHS guideline TA260 and (for most patients) the CGRP monthly injection drugs. A simple headache diary kept for 2 to 3 months is what evidences which category you're in.
NHS guideline CG150 in plain English
NHS guideline CG150 (Headaches in over 12s) covers acute treatment, prevention, when to refer, and what not to offer. Specifically for migraine:
- Acute: a triptan plus an NSAID or paracetamol, with an antiemetic if needed.
- Prevention: try preventives in turn, each at an adequate dose for at least 8 weeks.
- Address medication overuse before judging that preventives have failed.
- Refer to a headache clinic when preventives keep failing, when chronic migraine is suspected, or when CGRP/Botox is being considered.
Acute treatment
- Triptan (sumatriptan, rizatriptan, zolmitriptan, etc.) taken early in the attack.
- Plus an NSAID (ibuprofen, naproxen) or paracetamol.
- Antiemetic (e.g. metoclopramide, prochlorperazine) for nausea and to help absorption.
- Limit acute treatments to no more than 10 days a month to avoid medication overuse headache.
The preventive ladder
Preventives should be tried one at a time, at an adequate dose, for at least 8 weeks before deciding they've failed. CG150 names:
- Propranolol (a beta-blocker).
- Topiramate (anticonvulsant), with contraception advice because of teratogenic risk.
- Amitriptyline (off-label but recommended).
- Candesartan (commonly used second-line).
- Acupuncture (a course of up to 10 sessions) is also recommended for prevention in CG150.
Keep a list of what you've tried, the dose, how long for, and why it stopped. That list is the ticket to Botox and CGRP referral.
CGRP monthly injections
The CGRP (calcitonin gene-related peptide) monoclonal antibodies are the first migraine-specific preventives. They're self-injected (or infused) monthly or quarterly. All four are NHS-funded via NHS Technology Appraisals for people who meet the relevant TA criteria, and are prescribed by headache clinics, not GPs. Each TA is worth reading in full; the criteria differ in detail and are updated periodically.
- Erenumab (Aimovig), NHS guideline TA682. Recommended for preventing migraine in adults who have had at least 4 migraine days per month and where at least 3 preventive treatments have failed.
- Galcanezumab (Emgality), NHS guideline TA659. Recommended for chronic migraine where at least 3 preventives have failed.
- Fremanezumab (Ajovy), NHS guideline TA764. Recommended for chronic migraine where at least 3 preventives have failed.
- Eptinezumab (Vyepti), NHS guideline TA871. Recommended for chronic migraine where at least 3 preventives have failed. Given by IV infusion every 12 weeks.
The wording above is a plain-English summary, the TAs themselves contain the binding criteria (commissioning arrangements, stopping rules, response thresholds) and are updated periodically. Always check the current TA for the drug your specialist is considering. A letter to the GP naming the relevant TA and asking for a headache clinic referral is the standard route.
Botox for chronic migraine
NHS guideline TA260 recommends botulinum toxin type A for chronic migraine in adults whose headaches have not responded to at least 3 prior preventives, and where medication overuse has been addressed. Treatment is a series of small injections to the head and neck every 12 weeks, by a trained specialist. Continued only if there's a clear response.
Medication overuse headache
The single most common reason preventives appear to fail is medication overuse headache (MOH). Using acute treatments on more than 10 days a month (triptans, opioids, codeine-containing painkillers, paracetamol with caffeine) can produce a daily background headache that no preventive will fix.
CG150 says the overused medication must be withdrawn (often abruptly) before judging preventives. This is uncomfortable but usually decisive within 2 to 8 weeks.
What to ask your GP
- An adequate trial of CG150 preventives, recorded in your notes, drug, dose, duration, outcome.
- Honest review for medication overuse headache before declaring preventives failed.
- If chronic migraine criteria are met, referral to a headache clinic citing CG150 and NHS guideline TA260 (Botox) and/or the relevant CGRP TA.
- A headache diary template if you don't have one.
If your GP won't refer or hasn't recognised chronic migraine, a formal letter naming CG150 and the right TA is usually what moves it. Finally Seen writes that.
Frequently asked questions
What counts as chronic migraine?
Chronic migraine = headache on 15 or more days a month for at least 3 months, of which at least 8 days have migraine features. Below that threshold it's classed as episodic migraine. The distinction matters because chronic migraine unlocks Botox and (in many cases) CGRP injections under the NHS guidelines.
What preventives should I try first?
NHS guideline CG150 lists propranolol and topiramate as first-line preventives, with amitriptyline as an alternative. Candesartan is a common second-line. Each should be trialled at an adequate dose for at least 8 weeks before being called a failure.
How do I qualify for CGRP monthly injections?
Each NHS Technology Appraisal sets its own criteria, read the current TA for the drug your specialist is considering (TA682 erenumab, TA659 galcanezumab, TA764 fremanezumab, TA871 eptinezumab). They typically require chronic migraine plus a documented trail of failed prior preventives, but the exact number and definitions vary by TA. Your GP needs to refer to a headache clinic, these drugs are prescribed by specialists, not in primary care.
What about Botox?
Botulinum toxin type A is recommended by NHS guideline TA260 for chronic migraine in adults whose headaches have not responded to at least 3 prior preventives, and where medication overuse has been addressed. It's given as a series of injections every 12 weeks by a trained headache specialist.
Why do my preventives keep 'not working'?
The most common reason is medication overuse headache. Using acute painkillers (triptans, codeine, paracetamol with caffeine, opioids) on more than 10 days a month can stop preventives working and cause a daily background headache. CG150 says the overused medication has to be withdrawn before preventives can be properly assessed.