CGRP Migraine Medication: Insurance and Headache Calendar

When your doctor talks about a CGRP antibody for migraine, the next question is usually who pays. In England the NHS can offer these under NICE guidance when you meet its criteria. In the US your insurer decides, often through prior authorization. Either way, how many migraine days you have, and which preventives you have already tried, usually decide the outcome. You count those days on paper or in the migraine diary in Sam. Sam turns your entries into a doctor report as a PDF that counts your logged migraine days, instead of you adding them up by hand from a paper calendar. This text is general information, not medical or legal advice.

This text says nothing about whether a treatment is right for you. That decision is for your doctor. Here we explain how access and funding work in the UK and the US, and why a headache diary over months is the useful, honest step.

What are CGRP preventives for migraine?

CGRP antibodies are a class of preventive treatment for migraine. They are given as injections, and one as an infusion. The four antibodies are erenumab, galcanezumab and fremanezumab (injections) and eptinezumab (an infusion). They work on the CGRP pathway linked to migraine pain, and NICE recommends them only after other preventives have not worked. In the US, many insurers still ask for earlier steps first.

This text names no preference and gives no dosing advice. Which drug, route and dose, if any, is a decision for a doctor who treats migraine.

Who can be offered a CGRP preventive in the UK?

NICE has appraised each of the four. Erenumab was appraised in 2021, galcanezumab in 2020, fremanezumab in 2022 and eptinezumab in 2023. The core criteria are similar across them.

NICE recommends these preventives for adults with at least 4 migraine days a month, only if at least 3 preventive medicines have not worked, are not tolerated or are unsuitable because of safety concerns. NICE also says treatment should be stopped after 12 weeks if migraine frequency has not reduced enough: at least 50% for episodic migraine, or at least 30% for chronic migraine.

Meeting NICE criteria does not mean you are handed a prescription. A specialist, often a neurologist, usually starts and reviews the treatment, and how it is funded can vary by your local NHS area and its formulary. NICE guidance applies to England, where the NHS must fund a treatment NICE recommends as an option, normally within 90 days. Scotland, Wales and Northern Ireland have their own routes.

How do prior authorization and step therapy work in the US?

In the US these drugs are approved for the preventive treatment of migraine in adults. There is no single national coverage rule. Your insurer and its formulary decide, and most plans apply prior authorization.

Many plans also use step therapy. That means you usually need to show you have tried, failed or not tolerated other preventive medicines first before a CGRP preventive is approved. The number varies: one oral preventive in Aetna's policy, one from each of two classes at Highmark, two from a list at UnitedHealthcare. Highmark defines episodic migraine as 4 to 14 headache days a month, while Aetna sets no minimum number of migraine days for first approval.

Reauthorization often happens around three to twelve months. It often needs a documented reduction in migraine days from your baseline. That is directly where a consistent diary helps: it gives your doctor the numbers to show the change.

Some manufacturers offer savings cards for eligible commercially insured patients. These can lower your out-of-pocket cost, but they are not available to people on Medicare, Medicaid or other government programs, and the terms change and cap. Ask your pharmacy and your insurer for current details rather than trusting a figure in a blog.

Does a headache diary help?

Yes, in a practical way. The criteria in both systems run on numbers: how many migraine days you start with, and how that changes. A diary over months gives your doctor that history when the questions come up.

• For the NHS, the 4 migraine days and the response at the 12 week check are both counts.
• For US insurers, the baseline and the reduction at reauthorization are both counts.

A diary is documentation for the conversation with your doctor. It is not a form your insurer will accept on its own, and it does not guarantee any decision. But without it, you are asked "how many days" at the appointment and left to add up months from memory.

What you can record before the conversation

Two things help, and both take little time each day.

First, a list of the preventives you have tried. One line per drug: the name from the packet, when you started and stopped, who prescribed it, and in your doctor's words why it ended. These are your notes, not proof, and "not worked", "not tolerated" and "not suitable" are the terms your doctor will use.

Second, your migraine days over months. Record the day, strength, duration, aura if any, and any acute medicine you used. Count the days per month before treatment and after it starts. You can keep this history on paper or in Sam. Our guide to chronic migraine day counts explains how migraine and headache days are counted.

Keep logging after the start

Coverage and care reviews come back around. In the UK the first review is early, and in the US reauthorization returns on a cycle. Keep logging in the months after you start, so the review has numbers from before and during treatment.

Do not stop a treatment on your own. If you have concerns, raise them with your practice. Your doctor decides whether to continue, pause or change.

Count your migraine days over months and take the report to the conversation

You bring months of numbers instead of a total done from memory in the waiting room.

• Every attack is an entry with date, strength, duration, aura and acute medication in the migraine diary, so you are not keeping a paper calendar you must add up later.
• The doctor report as a PDF counts your logged migraine days and days with acute medication for the period you choose, so the "how many days" question has a concrete answer.
• Entries you make today can carry last night's sleep and HRV from Apple Health when a value exists, a few taps from the entry.
• You log preventives as medications and note each dose.

Sam does not decide whether a treatment is right for you, and it does not complete insurance or coverage steps. That stays with your doctor and insurer.

Try Sam Health

Sam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.

General information, not medical or legal advice. Coverage rules, criteria and prices change, and your plan or NHS area may differ. Talk to your doctor, insurer or commissioning service about your own case.

Related reading

• Getting a copy of your medical records when changing doctor
• Chronic migraine: how many days count
• Migraine diagnosis: what now
• Workplace Accommodations for Migraine: Home Office

Sources

Updated: October 2026

• NICE: Erenumab for preventing migraine (TA682), Galcanezumab (TA659), Fremanezumab (TA764) and Eptinezumab (TA871)
• NICE: Headaches in over 12s: diagnosis and management (CG150)
• Aetna: CGRP receptor antagonists injectable, IV - step therapy policy
• UnitedHealthcare: CGRP receptor antagonists step therapy and prior authorization policies
• Highmark: CGRP inhibitors pharmacy policy (J-1207)
• Lilly: Emgality savings and support and Amgen: Aimovig paying for treatment
• National Headache Foundation: Commercial plan formularies for CGRP treatments