Uneven Brows After Treatment: Why Assessment Matters

The muscle balance that determines brow position, why it can shift after treatment, and why assessment prevents most of it

"One eyebrow is higher than the other."

It's one of the most common concerns patients bring after anti-wrinkle treatment. And it's also one of the most preventable if the assessment beforehand was thorough enough.

Understanding why it happens makes it considerably less alarming, and helps you know what questions to ask when choosing a practitioner.

Your brow position isn't fixed. It's a balance.

Two sets of muscles are working against each other, and your brow sits at the equilibrium.

Think of your brow like a tug of war.

On one side is the frontalis the broad muscle across your forehead. Its job is to lift the brow. When you raise your eyebrows, this is the muscle doing the work.

On the other side is a group of muscles that pull the brow downward including the corrugator (the muscle that creates frown lines between the brows) and several smaller muscles around it.

Where your brow sits at rest isn't determined by either side alone. It's determined by the current balance between both sides.

Anti-wrinkle treatment (the kind that temporarily reduces muscle activity) changes one part of that balance. Reduce the lifting muscle and the brow can drop. Reduce the pulling-down muscles and the brow can rise. Change one side unevenly between left and right, and the brows can end up sitting at different heights.

That's not a mysterious complication. It's a predictable consequence of how the balance has been altered.

Almost nobody has a perfectly symmetrical face before treatment

This is the part that surprises most people.

Here's something worth knowing: facial asymmetry is the rule, not the exception. One brow almost always sits naturally slightly higher than the other. One set of muscles is almost always slightly stronger than the other.

Most of the time, we don't notice this because our muscles have been compensating for it automatically for years, making the asymmetry effectively invisible.

When anti-wrinkle treatment reduces some of that muscular activity, the underlying asymmetry can become more visible. The treatment didn't create the asymmetry. It reduced the compensation that was disguising it.

I saw a patient who came to me convinced that treatment had made her brows asymmetrical. She'd brought photographs from the previous year her wedding, a holiday, Christmas. The difference between the two sides was clearly visible in every single photograph, going back years. She'd simply never noticed it. Treatment revealed what was already there.

This matters because it changes the question from "what went wrong?" to "what wasn't assessed beforehand?"

Three specific ways the balance can shift

The muscles on one side are reduced more than the other.

If the pulling-down muscles are reduced more on one side, the lifting muscle on that side has less opposition. That brow rises higher. The other brow stays where it is. The result is a noticeable height difference even though the original intention was just to soften the lines between the brows.

The lifting muscle is reduced too much.

If the frontalis is weakened more than intended or more than the face can accommodate the brow drops. Sometimes the upper eyelid feels heavier as a result. This is one of the most common complaints after treatment, and it's usually a consequence of the lifting muscle being reduced in a face where it was already working hard to maintain the brow position.

A pre-existing difference becomes visible.

If one brow was naturally higher before treatment, giving both sides an identical treatment doesn't necessarily produce a symmetrical result. In some faces, treating both sides the same actually makes the difference more obvious, because the treatment reduces the muscular activity that was disguising the underlying asymmetry.

The Mephisto brow what it is and why it happens

One of the more recognisable outcomes, and one of the most misunderstood.

Some people notice that after treatment, the outer edge of one or both brows lifts sharply upward, creating an exaggerated pointed shape sometimes called a Spock brow or Mephisto brow.

This happens when the inner portion of the forehead has been treated, reducing muscle activity in the centre, while the outer portion remains more active. The outer muscle fibres, no longer balanced by the central ones, continue to lift the outer brow creating the characteristic peak.

It's completely explicable. It's not a random reaction. And once you understand the mechanism, it can usually be addressed by treating the outer fibres specifically which reduces the activity that's creating the peak.

Why correcting it requires a new assessment, not just more treatment

The visible result doesn't tell you what caused it.

The same visible outcome one brow sitting higher than the other can result from different causes. It might be uneven reduction of the pulling-down muscles. It might be that the lifting muscle on one side was reduced more. It might be a pre-existing asymmetry that's now more visible.

Those three situations require different responses. Applying more treatment without first working out which situation you're in can shift the problem rather than resolve it.

The right approach is a reassessment looking at both brows at rest and in animation, ideally around two weeks after treatment when the full effect has developed, and understanding which part of the balance has actually shifted.

When waiting is the right answer

Sometimes the most honest thing I can say is: let it wear off.

If the frontalis has been significantly over-reduced meaning the muscle that lifts the brow is doing less than is wanted adding more treatment won't help. There isn't a way to undo a reduction in muscle activity.

In this situation, time is genuinely the most appropriate response. Anti-wrinkle treatment is temporary. Over the following weeks and months, the muscle activity gradually returns. The brow recovers.

I know that isn't satisfying if you're looking at it every morning. But it's honest, and sometimes honesty is more useful than false reassurance.

What good assessment looks like before any treatment

The injection is the last few minutes. The assessment before it is the most important part.

Before any treatment near the brow, a proper assessment should include:

• Looking at both brows at rest are they sitting at the same height naturally?

• Watching both brows during animation does one side raise more strongly? Does one side have stronger downward pull?

• Understanding the patient's previous treatment history what was done before, where, and how they responded

• Discussing what the patient actually wants lifting? Softening? Just removing lines?

And importantly: discussing any natural asymmetry before treatment, not after. If one brow sits naturally higher, the patient should know that before treatment begins and the plan should account for it.

Identical treatment on asymmetrical anatomy doesn't produce a symmetrical result. Assessment tells you when to treat the two sides differently.

Frequently asked questions

Why is one eyebrow higher after treatment? Usually because the balance between the lifting and pulling-down muscles has shifted unevenly or because a pre-existing asymmetry has become more visible with reduced muscular compensation.

What is a Mephisto or Spock brow? An exaggerated upward peak at the outer brow, caused by the outer forehead muscles remaining active while the central forehead has been treated. It can often be addressed by specifically treating the outer fibres.

Can it be corrected? Often yes, depending on the cause. Some patterns can be addressed once the full treatment effect has developed. Others are better left to wear off naturally over time.

How long should I wait before getting it reassessed? Around two weeks is usually when the full effect has developed and the picture is clearer. Your practitioner may advise differently depending on what's happened.

Was my face symmetrical before treatment? Almost certainly not completely facial asymmetry is normal. The more useful question is whether that asymmetry was identified and discussed before treatment.

Where I'd start

At Juvenology, we assess and photograph both brows at rest and in animation before any treatment. If natural asymmetry exists which it usually does that's part of the conversation before the treatment, not a surprise after it.

The aim isn't to make every face perfectly symmetrical. It's to understand your face well enough to treat it deliberately.

About the author

Marina Kostadinova-Yankova is the founder of Juvenology Clinic in Maidstone, Kent.

Before moving into aesthetics, Marina spent six years in cardiac nursing at KIMS Hospital, followed by two years as an Aesthetics Nurse Specialist at Spencer Private Hospitals. She has led her own clinic for eight years.

She has completed the Certified Longevity Physician CME Course at the Geneva College of Longevity Science, and is a HeartMath Certified Practitioner through the HeartMath Institute Interventions Program.

Marina is a member of the British Association of Cosmetic Nurses and the Royal College of Nursing, and is JCCP verified.

Last reviewed August 2026.