Botulinum Toxin Injection (Migraine/Spasticity)

Botulinum toxin injection for migraine or spasticity is a treatment in which a highly purified protein — derived from a bacterium called Clostridium botulinum — is injected into specific muscles to block the nerve signals that cause pain or abnormal muscle tightness.

When the toxin is injected into a muscle, it temporarily prevents the nerve endings from releasing a chemical messenger called acetylcholine (the signal that tells muscles to contract). In migraine treatment, this reduces the chain of nerve signals thought to trigger headache attacks. In spasticity (abnormal, involuntary muscle stiffness or spasm), it allows overactive muscles to relax, making movement easier and reducing discomfort. The effect is not permanent — the nerve endings gradually recover over several months, so injections are typically repeated on a regular schedule.

Doctors use botulinum toxin injections when a patient's migraine or muscle stiffness has not responded well enough to standard medications, or when those medications cause unacceptable side effects. The two main groups of conditions treated are chronic migraine and spasticity linked to neurological disease or injury.

• Chronic migraine — headaches occurring on 15 or more days per month, with at least 8 of those days meeting the criteria for migraine.
• Upper-limb spasticity (arm and hand stiffness) — commonly seen after stroke, traumatic brain injury, or multiple sclerosis (a disease where the body's immune system damages the protective coating of nerves).
• Lower-limb spasticity (leg and foot stiffness) — including equinus foot (a condition where the foot is fixed in a downward, tiptoe position) after stroke or cerebral palsy (a group of conditions that affect movement and muscle tone from birth or early childhood).
• Cervical dystonia (torticollis) — a condition where neck muscles contract involuntarily, pulling the head into an abnormal position.
• Hemifacial spasm — involuntary twitching of muscles on one side of the face.
• Blepharospasm — uncontrolled blinking or forced closure of the eyelids.

Botulinum toxin injections are generally not suitable in certain situations. Your neurologist will assess these carefully before recommending the treatment.

• Known allergy to botulinum toxin or any of its ingredients.
• Active infection at the planned injection sites.
• Neuromuscular junction diseases such as myasthenia gravis (a condition where the immune system attacks the connection between nerves and muscles) or Lambert-Eaton syndrome, because the toxin may worsen muscle weakness.
• Pregnancy or breastfeeding — safety data are limited.
• Current use of certain antibiotics or other medications that may interact with the toxin — the doctor will review the full medication list.

Botulinum toxin injections are generally well tolerated, but like any medical procedure they carry some recognised risks, ranging from minor local effects to less common complications.

• Pain, redness, or bruising at the injection sites — the most common reaction, usually settling within a few days.
• Temporary headache — sometimes occurs in the days following migraine injections.
• Neck pain or muscle weakness near the injection area — can make it temporarily harder to hold the head upright after cervical injections.
• Drooping of the eyelid (ptosis) or eyebrow — if toxin spreads to nearby muscles around the eye.
• Difficulty swallowing (dysphagia) — more likely when injections are given close to the throat or neck muscles.
• Flu-like symptoms such as mild fatigue or a feeling of general unwellness — usually short-lived.
• Spread of toxin effect beyond the injection site — in rare cases, weakness can occur in muscles that were not targeted; this is more likely at higher doses.
• Allergic reaction — serious allergic responses are uncommon but require immediate medical attention.
• Reduced effect over time — a small number of patients develop antibodies (proteins made by the immune system) to the toxin, which can reduce its effectiveness with repeated treatments.

Preparation for botulinum toxin injections is generally straightforward because no anaesthesia (medication to make you unconscious) is required and the procedure is usually done in an outpatient setting, meaning you go home the same day. Your neurologist will guide you through the specific steps based on your condition.

Before the appointment, patients are usually asked to:

• Continue eating and drinking normally — fasting is not needed for this procedure.
• Inform the doctor of all medications, supplements, and herbal remedies being taken, particularly blood thinners (medications that reduce clotting) and muscle relaxants, as these may need to be paused or adjusted.
• Avoid alcohol for at least 24 hours before the appointment, as it can increase bruising.
• Avoid vigorous exercise on the day of the procedure.
• Wash the skin over the injection areas and avoid applying lotions, creams, or make-up to those areas on the day.

The doctor will usually review a headache diary (for migraine patients) or a functional assessment (for spasticity patients) to map out exactly which muscles to target. Blood tests are not routinely required, but if you are taking blood thinners a clotting check may be requested. Imaging such as MRI is not needed for the injection itself but may have already been done as part of your diagnosis.

The procedure itself typically follows these steps:

• You are seated or lying down in a comfortable position, depending on which area is being treated.
• The doctor cleans the skin at each planned injection site.
• A very fine needle is used to inject small amounts of the toxin into the targeted muscles. For chronic migraine, multiple injection points are usually mapped across the forehead, temples, back of the head, neck, and shoulders. For spasticity, the injections are focused on the specific overactive muscles identified in your assessment.
• Electromyography (EMG — a technique that measures electrical activity in muscles) or ultrasound guidance may be used to help place the needle precisely into the correct muscle, particularly for deeper or harder-to-locate muscles.
• The total number of injection sites and the session length vary depending on the condition being treated and the muscles involved — your doctor will explain what to expect for your individual plan.
• After the last injection, the skin is checked and a small dressing or cold pack may be applied if needed.

Because no sedation (medication to make you drowsy or sleepy) is used, most patients can leave the clinic shortly after the injections and resume light daily activities the same day. The full effect of the toxin on muscles typically builds gradually over the following days to weeks, so immediate improvement is not always noticeable. Your neurologist will schedule follow-up appointments to assess how well the treatment has worked and to plan the next injection cycle if needed.

• Stay upright for several hours after the procedure — avoid lying flat or bending the head forward for at least two to four hours, as this may help prevent the toxin from spreading to unintended muscles.
• Avoid rubbing or massaging the injection sites for the rest of the day.
• Do not do strenuous exercise or heavy physical activity for the remainder of the day.
• Avoid alcohol on the day of the procedure to reduce bruising.
• Apply a cold pack gently to any sore spots if the doctor advises it — never apply direct heat to the injection sites in the first 24 hours.
• Keep a headache diary or note any changes in muscle function, as this information helps the doctor assess effectiveness at the follow-up visit.
• Contact the clinic promptly if you notice unusual weakness beyond the treated area, difficulty swallowing or breathing, signs of a severe allergic reaction, or significant worsening of any symptoms.
• Repeat injections are usually planned every few months — the exact interval depends on your condition and how you respond, and your doctor will decide the schedule.
• Long-term, the aim is to reassess at each cycle whether the treatment is still needed, whether the dose or injection sites should be adjusted, and whether any lifestyle changes — such as physiotherapy (exercise-based rehabilitation) for spasticity — can complement the injections.