Frown Lines: Causes, Assessment & Treatment Options
The vertical creases between the brows are made by two muscles whose fibres run across the brow rather than up it: the corrugator supercilii, which pulls the brow inward and down, and the procerus, which pulls the centre of the brow down. Every time they contract they fold the skin at right angles to themselves, which is why the lines run up and down while the lines on the forehead run across. This is the deepest folding point on the face, so the creases etch earlier and hold longer than lines elsewhere. It also means that the rung which reaches the muscle does not only flatten the line: it changes the pull on the brow, and medial brow position is part of the decision rather than a footnote to it. This site is about why the lines are there, whether they need anything done, and what each path reaches and leaves alone.
Patient education reviewed by Tongchun Mao, MD. A new one-sided change, a brow or lid that has begun to droop, or any change in vision should be assessed medically before anything cosmetic is considered.
Six things that produce a glabellar crease
The first two are the mechanism and everything else acts on top of them. The last two are the reason an assessment asks about spectacles and screens before it discusses treatment. Which of these is doing the work decides what any rung of the ladder can reach.
The corrugator supercilii pulls inward and down
This muscle runs from the inner rim of the orbit across to the skin above the middle of the brow, so its fibres lie roughly across the brow rather than up it. When it shortens, it draws the brow inward and down and gathers the skin over it. The fold that produces is at right angles to the pull, and that is why it runs vertically. The paired columns over the two corrugators are the creases most people mean when they point at the middle of the forehead.
The procerus pulls the centre of the brow down
The procerus runs from the bridge of the nose upward between the brows and pulls the centre of the brow downward. It produces the horizontal lines across the root of the nose and it deepens the same vertical creases from the other direction. Most glabellas are a mixture of the two patterns, and the proportion differs between people, which is why two faces with equally deep lines are not necessarily the same problem.
Repetition etches the line into the skin
A crease that appears only when the face is frowning is a fold. A crease that is still visible with the face completely relaxed is a groove in the skin itself. The second is what decades of folding produces, and it is the part that no muscle-relaxing treatment reaches completely. It is also the part that decides how much of the line is left once the muscle is quiet.
Sun damage and collagen loss
Skin that has had a great deal of sun loses the collagen that lets it spring back after being folded. The same number of folds leaves a deeper and more permanent groove in that skin than in skin that has been protected. This is why two people with the same frown and the same muscles can reach their fifties with very different lines, and why protection is a treatment rung rather than advice.
A strong frowning habit, often deeper on one side
Concentration, reading, bright light, driving into low sun and long stretches at a screen all keep the brow working. Almost everyone has a dominant side, so one column is usually deeper than the other, and the difference is a habit pattern rather than a disease. It is worth knowing which side dominates, because it is the side that responds most obviously to anything that reduces the pull.
Uncorrected vision and eye strain
Spectacles that are the wrong prescription, an eye that turns or is strained, and dry or irritated eyes all make a person squint and frown more than they realise. This is a genuine contributor rather than a consolation explanation, because correcting it removes part of the drive to the muscle. It is also the one cause on this list that is worth investigating for its own sake rather than for the line.
When a crease is not a cosmetic question
Almost every glabellar crease is an appearance concern, the assessment is unhurried, and the answer is often that nothing needs doing. A small number are the visible part of something else, and what separates them is how the change arrived rather than how deep it looks. A line that has appeared over weeks, or that is clearly present on one side only when the face was previously symmetrical, is the finding that matters most, because the ordinary causes act on both sides over years. A brow or an eyelid that has begun to droop, a face that has become weak on one side, numbness, or a change in how the eye closes all point away from the skin and towards the nerve that supplies it, and they need a doctor rather than an aesthetic consultation. Any change in vision, double vision, or a headache that has come with a change in vision makes the assessment urgent rather than routine. A new deep line that arrives with weight loss, with a change in the general health of the skin, or with a rash along the crease also belongs with a physician first. None of this means treatment is forbidden; it means the cause has to be established and the timing has to be right. Where none of it is present, the ordinary conversation about muscles, skin and brow position can begin on a sound footing, and that conversation is what the rest of this site is about.
Five observations that decide the plan
A photograph taken in one light shows a line. It does not show whether the line is a fold that only appears on movement or a groove that is there at rest, which muscle is producing it, or what the brow would do if the muscle were quiet. Those are the questions the assessment exists to answer, and none of them can be answered from a picture.
The face at rest, before anything is asked of it
The first observation is made with the face completely relaxed, in light from the front rather than from above. Whatever is visible then is the etched component, the part that lives in the skin rather than in the movement. It sets the ceiling for every rung of the ladder, because a muscle-relaxing treatment cannot reach what is already a groove.
The same face under a held frown
The patient is asked to frown hard and hold it. A line that deepens dramatically under load and disappears at rest is produced almost entirely by muscle pull and answers to the muscle rung. A line that is equally deep at rest and under load is largely etched, and the muscle rung reaches only part of it. The comparison between the two states is the single most useful observation in this area.
Resting brow position and shape
The height of the medial brow, the height of the lateral brow, the shape of the arch and the position of the lid edge are recorded before anything is discussed. These are the measurements that make the brow-position trade a decision rather than a surprise. A brow that already sits high, or an arch that is already sharp, is a brow that has less room to change without the change becoming the complaint.
Asymmetry, side by side
The two sides are compared in the same light with the face at rest and then frowning. Most people have a dominant side and a difference of some degree, and where that difference has been stable for years it is part of the face rather than a finding. A difference that is new, that is progressing, or that comes with weakness is a different matter and is investigated before it is treated.
Which depressor dominates, and what the skin has kept
The pattern is read from the creases themselves: paired vertical columns point to the corrugator, horizontal lines across the nasal root point to the procerus, and most faces show both in some proportion. The history then covers sun exposure, smoking, previous treatment and when it was given, spectacles and eye strain, the hours spent reading or at a screen, and the family pattern. Taken together these decide what is worth doing and what is not.
The ladder, from sun protection to the ceiling
The rungs run from measures that cost nothing to procedures, and the useful part of the ladder is not the order but the matching. Each rung answers one part of the problem, and a rung used against the part it cannot reach is either wasted or disappointing. At the bottom, daily sun protection and a short routine suited to a folding area change the skin's capacity to spring back after being folded; they are the base every other rung sits on, and on their own they change the surface rather than the muscle, so their ceiling is low. Above that sits the work of removing the drive to the muscle: spectacles that are actually right, an eye that is not strained, and a habit that is noticed. Then comes the rung that reaches the mechanism, relaxing the corrugator and the procerus so that the skin stops being folded; this flattens the crease while the muscle is quiet, it wears off over months, and it changes the pull on the brow at the same time. Resurfacing — the fractional laser, microneedling and peel categories — comes after it rather than instead of it, because it works on the groove that is left in the skin and that work is lost if the fold is still happening daily. Filler in the glabella is a selected-case rung with a vascular risk that has to be accepted explicitly, and it is not a substitute for the muscle rung. Doing nothing is a legitimate choice at every rung, and for a stable line in a face that moves normally it is often the honest answer. One limit does not move: the crease softens, the muscle keeps working, and maintenance is the trade.
Four ways people make this worse
The first is to treat the surface while the fold is still being made every day. Resurfacing a crease that is folded hundreds of times a day loses most of its result, and the money spent on it is the part that cannot be recovered. The second is the mirror image: to accept the muscle rung from someone who has not looked at the brow at rest, because the line is not the only thing that changes and the brow shape is not always improved by it. The third is to spend years and a good deal of money on creams, patches, rollers and devices for a crease whose cause is the pull of two muscles, because a topical changes the surface of the skin and cannot stop a muscle from folding it — the delay is the only part of that list that costs anything real. The fourth is to treat a change that arrived over weeks, a one-sided change in a previously symmetrical face, a drooping brow or lid, weakness, numbness or any change in vision as an appearance problem, when each of those needs a doctor and one of them is urgent. None of these are rare. Each of them is easier to avoid at the start than to repair afterwards, and each begins with a treatment chosen before the question was asked.
If the decision moves toward treatment
This site deliberately stops short of describing procedures, because the injections and the devices themselves are explained properly elsewhere in this cluster. The category of treatment that relaxes the corrugator and the procerus is set out on the wrinkle-relaxing injection pages, and the assessment and technique are described on Dr. Mao’s surgical practice. Where volume rather than movement is the question in the same area, that belongs with dermal fillers, and the neighbouring changes to the upper face that are not creases at all are covered by facial aesthetic surgery. The wider picture of how this area is assessed sits within the Plastic Surgery & Aesthetics Medical Center. Before any treatment, quality and surgical safety describes how safety is organised inside the hospital, and booking an appointment explains how to arrange an assessment.
Frown lines: causes and the treatment ladder
Possible causes on the left and the ladder on the right, from least to most invasive. Note how many rungs sit below any procedure, that the muscle rung is the one that reaches the mechanism, and that the last line is the ceiling no rung reaches.
Guides
Ten guides, ordered the way the question usually unfolds: why the creases run the way they do, how they are assessed at rest and under movement, why one side is often deeper, and what each rung of the ladder reaches and leaves alone.
Why Frown Lines Are Vertical
Two muscles run across the brow, so every contraction folds the skin the other way: why glabellar creases are vertical, and what that changes about treatment.
Read the guide →How Frown Lines Are Assessed
Rest and animation, brow position, asymmetry and which depressor dominates: the observations an assessment makes, and what each one settles before any plan.
Read the guide →Frown Lines and Asymmetry: Why One Side Is Deeper
Most faces have a dominant side. When the deeper column is a lifelong habit pattern, and when a difference between the two sides needs investigating instead.
Read the guide →Why Frown Lines Etch More Deeply Than Other Lines
The glabella is the deepest folding point on the face. What decades of folding do to the skin, and why the muscle rung comes before the surface rung.
Read the guide →The Conservative Rungs for Frown Lines
Sun protection, a routine suited to a folding area and the habit behind the frown: what these change, why the ceiling is low, and why they still come first.
Read the guide →Botulinum Toxin for Frown Lines: What It Does
A muscle-relaxing injectable into the corrugator and procerus: what it changes, how long it lasts, the maintenance pattern, and the limits of relaxing a working muscle.
Read the guide →Start with the moving part, not the etched one
Arrange an assessment. We will record the resting crease, which depressor is doing the work, and where the brow and the lid edge sit now, then explain which rungs are worth discussing for your face and what none of them removes.
Frequently asked questions
Why are frown lines vertical when forehead lines run across?
Because a crease forms at right angles to the muscle that makes it. The corrugator supercilii and the procerus both run across the brow, so when they shorten they gather the skin and fold it up and down. The frontalis, which lifts the forehead, runs vertically up the skull, so its folds run across. The direction of the crease is a signature of the muscle underneath it.
Do frown lines need treating at all?
No. A crease that has been stable for years, in a face that still moves normally on both sides, is a feature of a working face rather than a condition. Treatment is a preference about appearance, not a medical necessity, and deciding against it is a legitimate answer at any point.
Do they get worse if I leave them alone?
Nothing accelerates because you decided not to treat them. The muscles keep working and the etched part of the line deepens slowly with time, sun exposure and the ordinary loss of collagen. That is a slow drift rather than a penalty, and it happens at the same rate whether or not anything is done about it.
What does relaxing the muscle actually change?
It removes the folding while the muscle is quiet, so the crease flattens during that time. It also changes the pull on the brow, because the muscles that hold the inner brow down are the ones being relaxed, and the medial brow often rises as a result. The groove that is already etched into the skin softens only partly, and it is still there.
Is it a problem that one side is deeper than the other?
Usually not. Almost everyone has a dominant side, and the deeper column is the side the muscle works harder on. A difference that has been present for years and that matches the rest of your face is part of your face. A difference that is new, that is increasing, or that comes with weakness or a drooping brow needs medical assessment instead.
How long does a muscle-relaxing treatment last?
Months rather than weeks, commonly in the region of three to four, and shorter or longer in individual people. It is judged by when the movement returns rather than by a date in a diary, because the same person can differ between treatments. Any interval you are given is an estimate for planning, and your own plan may differ.
Part of Lines and Wrinkles — 9 sites on this topic