The most common side effects of onabotulinumtoxinA for chronic migraine are neck pain and stiffness, injection-site soreness and temporary drooping of an eyelid or eyebrow. Most are mild and settle within weeks, because the effect of each round wears off.
The most common side effects of onabotulinumtoxinA for chronic migraine are neck pain and stiffness, injection-site soreness and temporary drooping of an eyelid or eyebrow. Most are mild and settle within weeks, because the effect of each round wears off.
Neck pain and stiffness is the effect people mention most, which makes sense given that part of the injection pattern is in the neck and shoulders. Soreness or small bruises at injection sites are common and brief. Temporary drooping of an eyelid or an uneven eyebrow position happens in a minority and reflects diffusion of the medication slightly beyond the intended muscle.
The treatment works on a cycle and wears off. That is the reason repeat rounds are needed, and it is also why unwanted effects resolve rather than persisting indefinitely. Injection technique and pattern can often be adjusted at the next round if a particular effect was troublesome, so reporting it is worth doing.
It is licensed for chronic migraine, which is defined by the number of headache days per month rather than by severity. If your migraine is episodic, this is not the right preventive and a different plan applies. Discuss pregnancy or breastfeeding specifically, and mention any neuromuscular condition before treatment. Tell whoever administers it about any previous cosmetic botulinum toxin treatment and when it was, because the timing affects planning. Report a troublesome effect between rounds rather than waiting for the next appointment; the pattern can often be adjusted at the next cycle, which is only possible if somebody knows.
Clinical Neurology Specialists has been physician-owned since 1998, when Leo Germin, M.D., FAANEM founded it. Five board-certified neurologists and four advanced practice providers see patients at the Las Vegas and Henderson offices, each with its own AANEM-accredited electrodiagnostic laboratory.
Clinical Neurology Specialists is an adult outpatient neurology practice for patients 18 and older. The practice performs no surgery and operates no imaging suite, infusion suite or interventional pain programme, and provides no emergency or inpatient care.
Physician-reviewed. Reviewed by the physicians of Clinical Neurology Specialists — board-certified neurologists, AANEM-accredited electrodiagnostic laboratories, physician-owned since 1998. Reviewed 1 August 2026. This article is general education for adults 18 and older and is not a substitute for a consultation.
Sources and further reading: American Academy of Neurology; MedlinePlus, National Library of Medicine; National Institute of Neurological Disorders and Stroke.
Adults 18 and older, at the Las Vegas and Henderson offices. Call 702-804-1212 or request an appointment online.