Botox (onabotulinumtoxinA) is a recognized preventive treatment for people who experience chronic migraines. This neurotoxin works by blocking the release of specific chemicals involved in pain transmission, thereby reducing the frequency and severity of migraine attacks. Because this treatment involves injecting the substance into muscles of the head and face, a common concern is whether this medical procedure will lead to unintended cosmetic alterations. Facial changes are a predictable consequence of the treatment, which can be either positive or negative, depending on the individual’s anatomy and the injection technique used.
The Targeted Treatment Areas
The protocol for administering Botox for chronic migraine prevention is standardized and based on the Phase III REsearch Evaluating Migraine Prophylaxis Therapy (PREEMPT) clinical trials. This protocol dictates the injection of a total dose (typically 155 to 195 units every 12 weeks) into 31 to 39 specific sites across seven muscle areas of the head, neck, and shoulders.
Crucially, this therapeutic approach includes several sites on the face and scalp that are also targeted in cosmetic procedures. These fixed sites include the procerus, corrugator, and frontalis muscles in the forehead and glabella (the area between the eyebrows), as well as the temporalis muscles in the temples. The intent is to target pain signaling pathways, but the mechanism of action is muscle relaxation, which inevitably affects the appearance of the treated areas.
Expected Changes to Facial Appearance
The muscle relaxation intended to relieve chronic migraine symptoms often results in predictable, and frequently welcome, cosmetic outcomes. By targeting the muscles responsible for frowning and squinting, the treatment naturally smooths the skin overlying them because the neurotoxin temporarily stops the muscle contractions that cause dynamic wrinkles.
Patients often notice a significant reduction in the “11” lines between the eyebrows, caused by the relaxation of the corrugator and procerus muscles. The treatment of the frontalis muscle in the forehead, while aimed at pain, also leads to the smoothing of horizontal forehead lines. These effects are a direct consequence of the therapeutic injections and are considered positive side effects by many patients.
The relaxation of these muscles may also lead to a slight lateral eyebrow lift, where the outer edges of the brows elevate slightly. This lift occurs when the muscles that pull the brow down are weakened, allowing the elevating muscles to have a dominant effect. However, the primary goal of the injection is medical, meaning the cosmetic results are a secondary benefit.
Managing Unwanted Aesthetic Outcomes
While some cosmetic changes are desirable, the primary concern is the risk of adverse aesthetic side effects. The most commonly reported unwanted outcome is brow ptosis, or the drooping of the eyebrows. This occurs when the frontalis muscle is over-relaxed, allowing the brow to fall, which can make the eyes appear smaller or give the face a tired expression.
A less common, but more severe, side effect is eyelid ptosis, where the neurotoxin inadvertently tracks into the muscle that elevates the eyelid. This can impair vision and is generally a result of the substance diffusing from the injection site to adjacent, unintended muscles. The risk of these adverse effects is minimized by choosing an experienced injector who understands the precise anatomy of the facial muscles.
Injectors can mitigate the risk of droopiness by carefully mapping the muscles and adjusting the injection depth or dose based on individual anatomy. Injecting the frontalis muscle higher in the forehead and avoiding the lower portion can help prevent the brow from sagging. If a droop does occur, supplementary injections into the opposing muscles can sometimes provide a subtle lift to restore symmetry.
How Long Facial Effects Last
All facial effects, both the desired smoothing and any unwanted side effects, are temporary because the body naturally metabolizes the neurotoxin. The duration of the therapeutic effect for chronic migraine is approximately 10 to 12 weeks, which corresponds directly to the timeline for the aesthetic changes. The treatment cycle is set at 12 weeks to maintain consistent pain prevention.
If a patient experiences brow or eyelid ptosis, the effect will gradually diminish as the neurotoxin wears off and the muscle function returns. While it may take the full 10 to 12 weeks for complete resolution, noticeable improvement in unwanted cosmetic effects often begins within a few weeks. The reversibility of the effects offers reassurance, as any temporary change is not permanent.