A patient presents with a heavy brow after botox and asks you to fix it. What she means is: lift this side back up. And the honest answer, which most injectors deliver badly or not at all, is that you cannot. Not with a different dose, not with a better technique, not with anything in a neurotoxin vial. Dr. Chris Croley states the constraint in one sentence: "There's no way that we can elevate the side that we've caused heaviness on."
This is not a limitation of skill. It is a property of the drug, and understanding it properly changes what you offer, what you promise, and what you say in the consultation before anything goes wrong.
Neurotoxin is a subtractive drug
Botulinum toxin does exactly one thing clinically: it prevents muscle contraction. It has no mechanism for producing contraction, restoring contraction, or accelerating the return of contraction in a muscle that has already been blocked. It subtracts movement. It cannot add movement.
Dr. Croley draws the clinical boundary from that: "With neurotoxins specifically, we can only treat the muscle that's moving. Anywhere that's not moving — even if it's, you know, the side that the patient likes — we can't really do anything different with that side. We can only treat the dynamic movement, or the muscles that are moving, with our neurotoxin."
Two things follow, and both are uncomfortable.
In any asymmetry, your only available move is on the strong side. The weak side is not a target. There is nothing to treat there, because there is no movement to remove.
Symmetry is therefore always achieved by levelling down. You bring the functioning side down to meet the weakened one. You never bring the weakened one up. There is also no reversal agent for botulinum toxin in the way that hyaluronidase reverses hyaluronic acid filler — once the toxin is bound, the only route back is time.
Why the brow is where this hurts most
Dr. Croley identifies the forehead as the region where clinicians meet this constraint most often, and explains precisely why it is so unsatisfying for the patient.
"Oftentimes — I think we will most often see this is in the frontalis, or the forehead. Patients have one side that's higher than the other, that's moving more than the other, and they want that treated. But in general they like the higher side. And all we can do is lower the higher side."
Read that twice. The patient's complaint is the heavy side. The patient's preference is the high side. And the only thing you can do is remove the thing she prefers.
This is the central awkwardness of neurotoxin correction. The correction moves the face away from what the patient wanted, in order to make it match. She does not walk out with the brow position she came in wanting. She walks out with both brows at the lower position, which is symmetric and is very often not what she meant by "fix it."
The same dynamic runs through the lower face. In the published correction case Dr. Croley reviews, one side of the smile was overactive and the other relatively flat. The plan treated the elevator on the overactive side. "We intentionally lowered the smile on the side that was overactive... Many patients will not like that. They want to have that elevated smile. But if we want to make her symmetric, we can't change the side that's not moving. We have to impact the side that is moving too much."
And his assessment of the result is not a sales pitch: "Even with animation, she has a relatively flat appearance. And so because of that, many patients do not want those smile elevators treated."
That is a faculty member saying, on camera, that the technically successful correction produces a face many patients would decline. Keep that framing intact when you have the conversation. It is the truth, and a patient who hears it before the injection is a patient who will not feel misled after it.
The three real options
Once you accept that lifting the heavy side is off the table, the decision set is small and clear. Present all three.
1. Level down. Treat the moving side to match the weakened side. This produces the best symmetry available and costs the patient the movement she liked. It is the right choice when the asymmetry is conspicuous, when the patient has a fixed event on the calendar, or when the patient's stated priority is symmetry over expressiveness. It comes with a caveat: the corrective dose adds its own duration, so it should sit below your usual dose for that muscle.
2. Wait. Do nothing and let both effects decay. This is a legitimate, often superior option, because the heavy side usually received a partial dose through diffusion and will recover ahead of the fully dosed side. Dr. Croley offers it explicitly as a plan: "Maybe it's a let's watch, and let's let this wear off, without continuing to chase that movement." The cost is a period of visible asymmetry. The benefit is no additional toxin and a face that returns fully to baseline.
3. Minimise rather than correct. Aim at reducing the appearance of the asymmetry rather than eliminating it, using a smaller dose than full levelling would require. Dr. Croley frames the goal question directly: "Are we trying to totally correct this? Are we trying to make this perfectly symmetrical? Or are we trying to minimise the appearance of the asymmetry?" These are different targets, and partial minimisation is frequently the best trade — some improvement in symmetry, some movement preserved, less toxin added.
What is not on the list is any version of "let me try to open that side up." There is no such intervention.
Where the constraint stops — and what is actually in your toolkit
"We can only treat what's moving" cuts both ways, and the second edge is more useful than clinicians usually notice. If neurotoxin only addresses movement, then any finding that is present at rest is not a neurotoxin problem.
Dr. Croley's assessment protocol makes the separation explicit: "We observe the patient at rest, and with animation. We diagnose the problem." Those are two different examinations producing two different problem lists.
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- Findings present only with animation are candidates for neurotoxin, subject to the constraint above.
- Findings present at rest — volume deficit, skin laxity, structural asymmetry, etched lines that persist when the face is still — are not neurotoxin problems and will not respond to more units. Chasing them with toxin is how injectors escalate dose without result, and it is a common route into the complications described elsewhere in this series.
This is the practical value of the dynamic versus static wrinkle distinction at the chairside: it is not a taxonomy exercise, it is a triage that tells you whether your drug is the right drug. Where the problem is volumetric rather than muscular, the relevant reasoning sits in facial volume loss and belongs to a different treatment category entirely.
A patient who presents at rest with one brow structurally lower than the other — a longstanding, pre-existing asymmetry — was never a good neurotoxin candidate for that complaint. Documenting it at rest before the first treatment is what prevents it from being attributed to your injection later.
This belongs in the consultation, not the complication visit
The single highest-value change most injectors can make is to move this conversation forward by one appointment.
If the first time a patient hears "we can only lower the other side" is at the visit where she is upset about a heavy brow, it lands as an excuse. If she heard it during the consent conversation for her first treatment, it lands as competence.
Build it into your standard consultation as a short, plain statement:
"Toxin works by reducing movement. That means if we ever end up with one side weaker than the other, the way we balance it is by bringing the stronger side down — there's no injection that lifts a weak muscle back up. Most of the time that kind of imbalance resolves on its own, and waiting is usually the better option."
Twenty seconds. It sets an accurate expectation, it pre-frames watchful waiting as a clinical choice rather than a fob-off, and it makes you the person who explained the drug rather than the person who got caught out by it.
It also documents well. A note that the subtractive nature of the drug and the levelling-down approach to asymmetry were discussed pre-treatment is a meaningful record.
What changes on Monday
Separate your two examinations. Photograph and assess at rest, then again with full animation, and keep the findings in separate lists. Only the animation list is a neurotoxin target list.
Change the verb you use with patients. Stop saying "fix" and "correct" about asymmetry. Say "balance" or "match." The first two imply restoration of what was lost. The second two accurately describe levelling down.
Note pre-existing asymmetry before you inject. Nearly every face is asymmetric at baseline. Recording it is the difference between a documented finding and an alleged complication.
Default to waiting unless there is a reason not to. The heavy side is usually on a shorter clock than your corrective dose would be. Absent a real timeline pressure, time is the better intervention.
And when mapping a treatment, keep in view that the muscles capable of producing this problem sit immediately beside the ones you are aiming at — the injection site reference is a reasonable orientation to those adjacencies.
This approach reflects Dr. Chris Croley's clinical practice as taught in Empire Medical Training's hands-on curriculum. Technique is learned under supervision; this article is educational and is not a substitute for training.
Working confidently within the drug's limits — and knowing which findings belong to a different modality altogether — is foundational rather than advanced. Empire teaches it in Complete Botox Training and Cosmetic Neurotoxins Training.
Frequently Asked Questions
Can more botox lift a brow that has dropped after treatment?
No. Botulinum toxin only reduces muscle contraction; it has no mechanism to restore or increase movement in a muscle that has already been weakened. Symmetry after a heavy brow is achieved by lowering the side that still moves, or by waiting for both effects to decay. There is no injectable that reverses toxin the way hyaluronidase reverses hyaluronic acid filler.
Is levelling down always the right answer for brow asymmetry?
No. It is one of three options, alongside waiting and partial minimisation. Levelling down gives the best symmetry but removes the movement the patient usually preferred, and the corrective dose lasts longer than the original diffusion effect. Waiting is often better when the patient has no fixed timeline.
Why does a corrected smile look flat?
Because correction of an asymmetric smile usually means weakening an elevator on the stronger side. Dr. Croley notes that the result is symmetric but relatively flat with animation, and that many patients decline this once they understand it. Establishing whether the patient values symmetry or expressiveness more should happen before the injection.
If a finding is visible at rest, will neurotoxin help?
Generally not. Neurotoxin acts on movement, so findings present in a still face — volume deficit, laxity, structural asymmetry, deeply etched lines — are not neurotoxin targets and will not respond to additional units. Assess at rest and with animation separately, and treat only the animation findings with toxin.
Disclaimer
This article reflects the clinical opinions and experience of Dr. Chris Croley, Chief Medical Officer, Empire Medical Training, an independent faculty member contributing to Empire Medical Training's curriculum. The views expressed are the author's own and do not necessarily represent those of Empire Medical Training.
It is professional education, not medical advice, and is no substitute for hands-on training or independent clinical judgment. Licensed clinicians remain responsible for their own patient selection, technique and outcomes, for verifying current product labelling, and for practising within their scope and applicable law. Empire Medical Training accepts no liability for reliance on this content.
