It has now been over a decade since Botox was first approved as a preventative treatment for chronic migraine in Australia. In that time the medicine itself has not changed, but our understanding of how to inject it well has. The standardised PREEMPT protocol — 31 injections, 155 units — is the published evidence base. What I have learned from injecting many hundreds of chronic migraine patients is that the protocol is the floor, not the ceiling. The real benefit comes from a bespoke, “follow the pain” approach.

This post explains what chronic migraine is, why Botox works, how the standard PREEMPT injection protocol is delivered, and why I add to it for every patient based on their individual pain distribution.

What is chronic migraine?

Chronic migraine is defined as 15 or more headache days per month, with at least 8 of those being migraine, for at least 3 months. It affects approximately 1–2% of adults — meaning hundreds of thousands of Australians. It is genuinely disabling: chronic migraine is one of the top causes of years lived with disability worldwide, and its impact on work, family, and quality of life is profound.

Despite this, chronic migraine remains under-diagnosed and under-treated. Many patients have spent years cycling through oral preventative medications — propranolol, topiramate, amitriptyline, candesartan, sodium valproate — before reaching specialist care. By the time Botox is being considered, most patients have already endured significant burden.

Why does Botox work for migraine?

The short version: Botox blocks the release of CGRP (calcitonin gene-related peptide) and other pain-signalling molecules from peripheral nerve endings in the scalp, temples and neck. CGRP is the central chemical messenger that triggers the neurovascular inflammation and pain of a migraine. By preventing CGRP release at the nerve terminal, Botox reduces the sensitisation that drives chronic migraine.

What it does not do — despite popular belief — is “paralyse the muscles” that cause headache. The mechanism of Botox in migraine is neurological, not muscular. Patients without muscle relaxation can still benefit, which tells us the muscle effect is not the key.

Interestingly, the CGRP monoclonal antibodies — Emgality, Ajovy and Vyepti — work on the same final pathway, just at a different point. They circulate in the bloodstream and neutralise CGRP or its receptor. Botox blocks CGRP release locally at the nerve terminal. Read more about CGRP medications.

The PREEMPT protocol — the standard 31 injections

The injection protocol used for chronic migraine was established by the PREEMPT clinical trials (2010). It specifies 31 injection sites across seven specific muscle groups, with a fixed total dose of 155 units of onabotulinumtoxinA:

• Forehead (corrugator, procerus, frontalis) — 4 sites
• Temples (temporalis bilaterally) — 8 sites
• Back of the head (occipitalis bilaterally) — 6 sites
• Neck (cervical paraspinal muscles bilaterally) — 6 sites
• Upper shoulders (trapezius bilaterally) — 8 sites

Doses are split across these sites — typically 5 units per injection. The actual injecting takes about 8 minutes; the whole appointment (consultation, discussion, injection, post-injection observation) takes 20–30 minutes. Most patients describe the procedure as easier than they had imagined.

Why I add to it — the “follow the pain” approach

Here is the issue with treating every chronic migraine patient with exactly the same 31-site pattern: not every patient’s pain lives in the same place.

Some patients have predominantly frontal pain — the standard PREEMPT pattern allocates only 4 forehead sites. Others have severe occipital and suboccipital pain — 6 sites at the back of the head may not be enough. Some have one-sided pain dominance that the symmetrical protocol does not account for. Some have prominent trigger points that need direct attention.

The PREEMPT trial protocol referenced this. The “Paradigm Protocol” used in PREEMPT permits additional injections in the temporalis, occipitalis and trapezius if the patient has pain in those areas — what the literature calls a “follow the pain” approach, on top of the fixed sites.

In practice, this means a bespoke injection pattern for every patient. After examining the patient and asking carefully where the pain is — where the migraine “lives” — I add injections at the relevant locations. A patient with a strong unilateral occipital component gets additional posterior injections. A patient with prominent temporal pain gets additional temporal sites. The standard PREEMPT framework is preserved, and PBS dosing limits are respected, but the technique is individualised.

In my clinical experience, this bespoke approach improves response rates. It is also more satisfying for the patient — they feel their actual pain pattern has been heard and addressed, not just treated against a template.

What does it feel like? Are there side effects?

The injections sting briefly — most patients describe each as a small pinprick. Ice or distraction can help, and the whole thing is usually over in under 10 minutes. The most common after-effect is mild neck stiffness or soreness for a day or two. Other potential effects, all uncommon, include:

• Mild brow heaviness (usually transient)
• Very rare temporary eyelid droop (ptosis) — I have seen this only once in my practice, and it resolved within days
• Injection-site itch or rash (less than 1%)
• Worsening of migraine for a few days (around 4% in clinical trials)

Serious side effects are uncommon when the procedure is performed by an experienced injector who knows the relevant anatomy.

How well does it work? Realistic expectations

The PREEMPT clinical trials showed 40–50% of chronic migraine patients achieved greater than 50% reduction in headache days per month with Botox. This is comparable to oral preventatives such as topiramate, valproate and amitriptyline — but with the advantages of 12-weekly dosing, few systemic side effects, and an entirely different side-effect profile.

In post-trial real-world data presented at the Congress of European Neurology (2017), 65% of first-time Botox patients were satisfied or very satisfied with the treatment. The benefit accumulates over the first two cycles — some patients see improvement after cycle 1, others need three cycles to reach their full response.

PBS continuation requires demonstrating at least 50% reduction in headache days after cycle 2. This is a high bar — it ensures the subsidy is targeted to clear responders. Patients who do not meet this threshold can switch to CGRP medications or other strategies.

Who qualifies under the PBS?

PBS-subsidised Botox for chronic migraine requires all of the following:

• Chronic migraine (≥15 headache days/month, with ≥8 being migraine, for ≥3 months)
• Failed adequate trials of at least 3 oral preventative medications from different classes
• Treatment prescribed by a neurologist or pain medicine specialist
• Not concurrently on PBS-subsidised CGRP therapy (you must choose one or the other under PBS)

A headache diary documenting your baseline is essential — both for diagnosis and for monitoring response. If you do not have one, that’s the first thing we will start.

Botox or CGRP — which one?

Both Botox and CGRP monoclonal antibodies are now PBS-listed for chronic migraine. They work on the same pathway from different angles, with broadly similar response rates. PBS rules do not permit concurrent subsidy of both — patients choose one or the other, although switching is permitted under authority.

Practical factors guide the choice: dosing frequency (12-weekly in-rooms procedure for Botox vs monthly self-injection for CGRP), preference for an in-clinic appointment vs at-home administration, history of medication-overuse headache (where Botox may help break the cycle), needle phobia, pregnancy plans, and cost considerations. We talk through this in detail at consultation.

For the full PBS-vs-PBS comparison and side-by-side criteria, see the dedicated page: Botox for Chronic Migraine — Sydney Headache Centre and CGRP Therapies.

How to access Botox for chronic migraine

Botox for chronic migraine is administered by accredited neurologists or pain medicine specialists. You will need:

1. A GP referral to a neurologist accredited for the PREEMPT protocol
2. A documented headache diary covering at least 1 month (more is better)
3. A list of previously trialled oral preventatives — name, dose, duration, and reason for stopping
4. Patience — the response is judged at cycle 2 (24 weeks from starting). The early weeks can feel slow.

At our Bondi Junction rooms, the standard journey is: consultation (where we confirm eligibility, plan the bespoke injection pattern, and explain expectations), PBS authority application, then the first injection cycle. Subsequent cycles are 12-weekly and increasingly brief as the technique is refined for each patient.

The bottom line

Botox is a powerful and well-evidenced preventative for chronic migraine. The PREEMPT protocol is the foundation, but the technique matters: a one-size-fits-all approach leaves response rates on the table. The “follow the pain” bespoke approach — placing additional injections at each patient’s individual pain distribution — is what good Botox injection looks like in 2026.

If you have chronic migraine and want to discuss whether Botox is right for you, please contact our Bondi Junction rooms or read the detailed treatment page at Sydney Headache Centre.

Related reading

• Chronic migraine Botox — PBS criteria and what to expect
• CGRP therapies — Emgality, Ajovy, Vyepti and Aimovig in 2026
• Migraine — types, triggers, and treatment
• Medication overuse headache
• Headache diary (online)
• For referring GPs

Dr Ron Granot is a consultant neurologist (FRACP) based in Bondi Junction, Sydney. He trained at Prince of Wales Hospital — Sydney’s leading headache neurology centre — and is an accredited Botox injector for chronic migraine using the PREEMPT protocol with the follow-the-pain extension.