Forehead lines:
causes, signs and why brow position matters

What causes forehead lines?

Forehead lines are caused by the frontalis, a broad sheet of muscle running from the hairline to the brows. It is the only muscle that raises the brows, and every raise folds the forehead skin horizontally. In youth the folds flatten the moment the muscle relaxes; as collagen thins with age and sun, the folds persist, first faintly and then at rest. Frequent raisers, expressive talkers and people who lift their brows when they concentrate write these lines earliest.

The frontalis does not act alone. It is in constant balance with the muscles that pull the brows down: the corrugators and procerus between the brows, and the outer part of the orbicularis oculi at the tail of the brow. When the depressors are strong, the frontalis works harder to keep the brows up, and the forehead lines deepen as a consequence. This balance is why the forehead is planned together with the frown and brow rather than in isolation, and the botulinum toxin page describes how the upper-face muscles are approached as a group.

There is a third cause that is often missed. In many people the frontalis is not idly expressive; it is holding heavy or hooded upper eyelids out of the visual field all day. The forehead lines are the record of that effort. Relax the muscle fully and the brows settle, the hooding lands on the lashes and the eyes feel heavy. The condition guide to forehead and frown lines calls this the compensation trap, and this page explains how brow position is read to avoid it.

What do forehead lines look like, and what does the brow tell you?

Forehead lines appear as horizontal creases, sometimes continuous across the forehead and sometimes broken into segments, that deepen when the brows are raised. In the early stage they vanish at rest. Later they remain at rest as fine lines, then as folds, and the skin between them can lose its evenness. One side is often deeper than the other, reflecting a habit of raising one brow.

The brow itself gives the diagnosis. At rest, the brow should sit at or a little above the bony rim of the eye socket, with the tail slightly higher than the head. A brow sitting low, or one that rises sharply when you are asked to look straight ahead with the forehead relaxed, suggests the frontalis is compensating for a heavy lid. Asking you to close your eyes gently, relax the forehead and then open them shows how much of the lid rests on the lashes without the frontalis helping. Asymmetric brows, a single raised tail, and lines concentrated low on the forehead each tell a different story and change where and how much treatment is placed.

At assessment the forehead is examined at rest, on a full raise, in a frown and with the eyes closed and reopened, and the upper lids are checked for skin excess and for a lid margin that sits low over the pupil. A heavy lid from the lid itself, rather than from a low brow, is a different problem, and the droopy and hooded eyelids guide sets out how it is told apart and where it is referred.

“Before relaxing a hard-working forehead, ask what it is working on — half the time it is holding your eyelids open.”

Dr Sin YongOn brow assessment before forehead treatment

In what order is treatment planned?

Treatment begins with the brow, not the lines. If the frontalis is compensating, the plan is conservative and often redirected: the depressors between and beside the brows may be treated so that the brow is not pulled down, the lower fibres of the frontalis are spared so the brow keeps its lift, and only the upper forehead is softened. Where the lid is the problem, the honest route is energy-based lifting aimed at the brow and lid, or referral for an eyelid assessment, rather than freezing a forehead that is doing a job.

Where the forehead is free to be treated, botulinum toxin is the direct answer to a line made by movement. It is a prescription medicine that reduces the nerve signal to the muscle. Dr Sin Yong maps the frontalis pattern and places small doses across the upper and middle forehead, adjusting for asymmetry and for how high the muscle is active, with the aim of softened movement rather than a still forehead. The glabella is usually treated at the same visit so that the brows are not pulled down once the frontalis is quieter.

Lines already present at rest are treated in the skin. Fractional laser and radiofrequency microneedling remodel the creased dermis; polynucleotides and skin boosters thicken thin forehead skin. Deep, static folds across a flat forehead occasionally warrant careful forehead filler, which is a high-caution zone because of the vessels that run there and is reserved for experienced hands. Lifting treatments such as HIFU at a shallow depth over the brow, or monopolar radiofrequency, are directed at brow position itself where that is the cause.

Who it suits and who should wait?

Botulinum toxin for forehead lines suits people whose lines appear mainly on raising the brows, whose brows sit at a comfortable height without effort, and who want softer movement rather than a still forehead. It also suits people with early static lines as the first half of a plan that adds skin treatment afterwards.

It is approached cautiously, or redirected, in people whose forehead is holding heavy lids open, who already have low brows, or who have had a heavy-feeling result from forehead treatment before. It is deferred in pregnancy and breastfeeding, with an active infection in the area, with a neuromuscular condition such as myasthenia gravis, with a known allergy to a botulinum toxin product, or with unreviewed medicines that affect nerve-to-muscle transmission. Anyone expecting toxin to lift a drooping lid, add volume to a flat forehead or remove lines etched at rest is offered a different route.

What are the risks, and when should you call?

The common effects are small bruises, tenderness and sometimes a mild headache, which settle. The risk specific to the forehead is a brow that drops or feels heavy because the frontalis has been relaxed more than the lids can afford, and an eyelid that droops if the medicine reaches the muscle that lifts the lid. A single raised outer brow can occur if the outer frontalis is left more active than the inner part. These effects last as long as the medicine acts and cannot be reversed on demand, though a raised brow can sometimes be balanced with a further small dose. Conservative dosing, brow assessment beforehand and pattern-mapped placement reduce the chance of them without removing it.

Call the clinic for a drooping lid or brow that bothers you, marked asymmetry, or double vision. Difficulty swallowing, speaking or breathing after any botulinum toxin injection needs urgent care at a hospital emergency department. The complication care page explains what to do if something feels wrong after a treatment, wherever it was done.

What determines the fee, and when should you see a doctor?

Singapore's rules prevent clinics from advertising prices, so this page gives factors rather than figures. The fee depends on whether the forehead is treated alone or with the frown and crow's feet, on the dose the muscle pattern needs, on the formulation chosen and on whether etched lines call for a separate skin-directed treatment. A written quote follows the consultation, and the fee page explains how quotes are prepared.

See a doctor when forehead lines sit alongside heavy or drooping lids, when one brow has started to sit lower than the other, when lines at rest are deepening despite sun protection, or when headache, eye strain or squinting has started with the lines. A new one-sided brow or lid droop needs medical review rather than a cosmetic appointment. The consultation process page describes how the assessment runs and what to bring.