A forehead indent has dozens of possible explanations, ranging from completely harmless anatomy you were born with to autoimmune skin conditions, old injuries, bone changes with aging, and side effects of medical procedures. In most cases the indent is a normal variant of skull shape that has been there for years without notice, but a new or deepening groove deserves attention because some causes are progressive. What matters most is whether the indent appeared suddenly, has been changing, or came with other symptoms.
Normal Skull Anatomy Is Not Perfectly Smooth
People tend to imagine the skull as a uniform dome, but the frontal bone has natural ridges, grooves, and openings that vary from person to person. One common source of a small indent just above the eyebrow is the supraorbital foramen or notch, a passage for nerves and blood vessels that supply the forehead skin. A cadaver-and-dry-skull study found that roughly half of specimens had a true foramen (a hole punched through bone) and the other half had a notch (an open groove at the brow ridge), with the exact split varying between individuals and sides of the face.1PubMed Central. Dimension, Location and Clinical Importance of Supraorbital Foramen and Notch: A Combined Cadaveric and Dry Skull Study When the foramen sits slightly deeper or the surrounding bone is thinner, you can feel or even see a small dip above the brow.
Beyond these openings, the frontal bone itself has a naturally variable contour. The metopic ridge, a faint raised line running vertically up the center of the forehead where the two halves of the frontal bone fused in infancy, can leave a visible groove on either side. Some people have a prominent frontal eminence (the rounded bump on each side of the upper forehead) that makes the area between them look slightly hollowed. None of these features are abnormal. If you run your fingers over your forehead slowly, you will probably feel at least one bump or dip you never noticed before.
En Coup De Sabre, a Rare Autoimmune Cause
If the indent is a narrow, line-like groove running roughly vertically on one side of the forehead, one condition worth knowing about is en coup de sabre morphea. The name is French for “struck by a sword,” because the lesion looks like a thin scar from a blade. It is a form of localized scleroderma, a condition in which the immune system triggers excess collagen production and tissue hardening in a limited area. The groove typically runs along the frontoparietal region, above the brow, and the skin overlying it often shows discoloration or a waxy texture.2PubMed Central. En coup de sabre morphea: an uncommon condition in Africa
In many cases the condition burns itself out over months to years, but it usually leaves behind permanent skin color changes and an indent in the affected area.3Ophthalmic Plastic & Reconstructive Surgery. Linear Scleroderma En Coup de Sabre: A Case Series With Eyelid Involvement and Management The depth of that indent depends on how deeply the process extended: some people lose only a bit of subcutaneous fat, while others lose underlying muscle or even bone. When the groove runs close to the eye, it can affect the eyelid or the tissues around the orbit, which is why ophthalmologists sometimes get involved.
The condition is uncommon, and it tends to appear in childhood or early adulthood. If you have noticed a slowly deepening, linear furrow on one side of your forehead with overlying skin changes, a dermatologist can usually diagnose it with a clinical exam and, if needed, a skin biopsy.
Progressive Hemifacial Atrophy
A related but distinct condition is Parry-Romberg syndrome, also called progressive hemifacial atrophy. Rather than a thin line, this involves slow, one-sided wasting of skin, fat, muscle, and sometimes bone across a larger area of the face. The affected area often starts around the cheek or eye socket and can expand to include the forehead, mouth area, teeth, jaw, and neck.4American Journal of Neuroradiology. Parry Romberg Syndrome: 7 Cases and Literature Review In some patients, a visible line of demarcation separates the normal side from the wasting side.5PubMed Central. Clinical and radiographic features of parry-romberg syndrome
Parry-Romberg typically begins in the first or second decade of life and progresses for several years before stabilizing. The forehead indent it produces is usually broader and asymmetric rather than a narrow groove. Because the process can erode bone, CT imaging sometimes reveals thinning of the frontal bone on the affected side. The exact cause remains unclear, but it is thought to involve autoimmune or neurovascular mechanisms. Researchers have debated for decades whether Parry-Romberg and en coup de sabre morphea are separate diseases or two points on a spectrum, and many clinicians now treat them as overlapping conditions.
Old Injuries and Depressed Skull Fractures
The forehead takes a disproportionate share of head trauma. In a study of patients surgically treated for depressed skull fractures, the frontal region was the most common fracture site, accounting for about a third of all cases.6PubMed. Assessment of the predictive factors and outcomes of surgically treated patients with depressed skull fracture at a tertiary hospital, Northwest Ethiopia A depressed fracture pushes a piece of bone inward, and even after it heals, the area can remain slightly sunken if the fragment did not realign perfectly. Many people who had a childhood fall or accident may not remember the injury well, only noticing the residual dent years later.
Not every post-trauma indent involves bone. A hard impact to the forehead can damage the fat layer under the skin without fracturing the skull. Fat does not always regenerate completely, so a localized dip in the soft tissue can persist indefinitely. If you know you hit your head at some point and the indent lines up with the spot, trauma is a reasonable explanation, though a doctor can confirm with imaging if you want certainty.
Temporary Indents from Pressure
Sometimes the indent is not structural at all. Prolonged pressure on the forehead from headbands, helmets, goggles, CPAP masks, or even sleeping in an unusual position can leave a visible dent that lasts hours or occasionally days. A military study evaluating a headband-style monitoring device found that participants reported temporary marks and indentations where the electronics had pressed against the forehead.7Military Medicine. Continuous SpO2-Monitoring Headband Is Acceptable for Military Operations The forehead’s thin layer of subcutaneous fat compresses easily, and the skin can hold the impression of whatever pressed into it, especially if you were asleep or the contact lasted hours.
These pressure-related indents resolve on their own as the tissue rebounds. If yours appears every morning and fades by midday, look at what your forehead is resting against at night. People who sleep face down or pressed into a firm pillow edge often find this explains the mystery. Switching to a softer pillow or changing sleep position is usually enough.
Steroid Injections and Fat Loss
Corticosteroid injections given near the forehead for various medical reasons can cause localized fat atrophy, leaving a visible dip in the skin. After a steroid injection, the fat cells in the area shrink in both size and number.8PubMed Central. Successful treatment of lipoatrophy with normal saline The result is a soft, sometimes circular depression at or near the injection site. A case report described a four-year-old girl who developed noticeable forehead fat atrophy one month after a single steroid injection near her eye for an unrelated condition; the indent resolved on its own within about a year.9PubMed. Forehead subcutaneous fat atrophy following a single steroid injection for acute Brown syndrome
The good news is that steroid-induced fat atrophy is often reversible, though recovery can take many months. In some cases clinicians have treated persistent depressions with saline injections or dermal fillers to restore volume. If you recently had a steroid injection anywhere on or near your forehead and a new indent appeared weeks later, this is a well-documented side effect worth discussing with the prescribing doctor.
Botulinum Toxin and Muscle Atrophy
Cosmetic Botox injections in the forehead work by temporarily paralyzing the muscles that create wrinkles. In rare cases, repeated treatments can lead to focal muscle atrophy, where the underlying muscle thins from prolonged disuse. Researchers have described small, round depressions appearing at Botox injection sites and hypothesized that the temporary loss of nerve stimulation causes the muscle to waste in that spot.10PubMed Central. Morphea-like lesions after botulinum toxin A injections The depressions tend to follow the “action halo” of the injected toxin, so they can appear slightly off-center from where the needle went in.
This is not common, and the effect is usually mild. But if you have been getting forehead Botox for years and gradually notice a flattening or small dips between treatments, muscle atrophy is a plausible contributor. Spacing out treatments or adjusting injection sites can help, and the muscle typically recovers over several months once injections are paused.
Bone Lesions That Erode the Skull
Less commonly, a forehead indent is caused by something happening inside the bone itself. The frontal bone can develop benign growths or cyst-like lesions that erode through the outer surface. Intraosseous hemangiomas, for instance, are slow-growing tangles of blood vessels within the bone that expand outward and can thin the outer layer of the skull. On imaging, these appear as well-defined lesions with a characteristic pattern of tiny internal spicules radiating from a central point.11PubMed Central. Spectrum of lytic lesions of the skull: a pictorial essay Other lytic lesions, including epidermoid cysts and eosinophilic granulomas, can produce similar erosion.
These conditions are mostly found incidentally on imaging done for other reasons. A palpable indent from a bone lesion usually feels firm and fixed to the skull rather than soft and squishy. It does not move when you press on it, and the overlying skin looks normal. The overwhelming majority of skull vault lesions are benign, but any new, firm, fixed dent that you cannot explain warrants a medical evaluation to rule out the small number of concerning possibilities.
How Aging Reshapes the Forehead
The bones of the face do not stay the same size and shape throughout life. Research using CT scans has shown that the facial skeleton undergoes measurable remodeling with age, particularly in the midface. The angle of the upper jaw decreases by roughly ten degrees between young adulthood and old age, and the eye sockets widen and deepen.12PubMed Central. Changes in the Facial Skeleton With Aging: Implications and Clinical Applications in Facial Rejuvenation The forehead itself can change as well. Gradual thinning of the frontal bone, combined with loss of subcutaneous fat and skin elasticity, can make previously unnoticeable skull contours more visible over the decades.
This is one reason people sometimes notice a forehead indent in their forties or fifties that they swear was not there before. It may genuinely be new in the sense that the overlying soft tissue was thick enough to mask it earlier. Fat loss accelerates in certain areas of the face with aging, and the forehead is one of the first places where the underlying bone topography starts to show through.
Congenital Causes in Infants and Children
When a forehead indent is noticed in a baby or young child, the list of possibilities shifts. Aplasia cutis congenita is a condition present at birth in which a small patch of skin (and sometimes deeper tissue) fails to develop normally. It most commonly affects the scalp, but lesions on the forehead have been reported. In one documented family, aplasia cutis congenita occurred across four generations along with heart defects and frontonasal cysts, suggesting an inherited pattern.13PubMed Central. Aplasia cutis congenita, congenital heart lesions, and frontonasal cysts in four successive generations
Other congenital explanations include premature fusion of one of the skull sutures (craniosynostosis), which can create ridges or depressions depending on which suture is involved, and dermoid cysts, which are small pockets of trapped skin tissue that form along embryonic fusion lines and sometimes present as a soft bump or dip near the hairline. Pediatricians routinely check head shape during well-child visits, so most structural issues in infants get flagged early. If a child’s forehead indent is growing, changing color, or accompanied by developmental concerns, imaging and specialist referral are standard next steps.
How Noticeable Is a Forehead Indent to Other People
If you are reading this article because you are self-conscious about a dent on your forehead, it is worth knowing that human perception of facial asymmetry is surprisingly forgiving. A review of the literature on discriminative thresholds found that people do not reliably detect brow asymmetry until the difference between sides reaches about three and a half millimeters, and they are even less sensitive to deviations along the chin (six millimeters before most observers notice).14Aesthetic Surgery Journal. Discriminative Thresholds in Facial Asymmetry: A Review of the Literature In practical terms, many indents that feel dramatic under your own fingertips fall below the threshold where a stranger across a table would register them.
Lighting and angle matter enormously. You probably first noticed your indent in a bathroom mirror with harsh overhead light, which is the worst-case scenario for any concavity on the face. Under normal daylight and at conversational distance, the same feature may be essentially invisible. That said, cosmetic concern is valid regardless of objective measurements. If the indent bothers you and imaging has ruled out a progressive cause, dermal fillers, fat grafting, or in some cases surgical recontouring are options that plastic surgeons routinely discuss with patients.
Why Modern Humans Have Flat Foreheads at All
Here is something most people have never considered: the flat, vertical forehead you are examining in the mirror is actually a recent development in human evolution. Our archaic ancestors had heavy brow ridges with a sloping forehead behind them. Research using computational modeling of an archaic hominin skull showed that those massive brow ridges were far larger than structurally necessary for biting forces or protecting the brain, suggesting they served a social signaling function.15Nature Ecology & Evolution. Supraorbital morphology and social dynamics in human evolution As human social groups became larger and more cooperative, the prominent brow ridge gave way to a flatter frontal bone and more mobile eyebrows capable of subtle emotional expression.
The trade-off is that a smooth, vertical forehead means any bump or dent stands out more than it would on a heavily ridged skull. Your indent might be completely unremarkable in an anatomical sense, just a minor variation in bone or soft-tissue thickness, but visible precisely because the canvas it sits on is so flat and featureless. That flatness is itself a product of selection for expressiveness, not structural perfection.
When to Get It Checked
Most forehead indents turn out to be normal anatomy or the residue of a long-forgotten bump. But a few red flags should prompt a visit to a doctor:
- New and growing: An indent that appeared recently and is getting deeper or wider could signal a progressive condition like morphea, Parry-Romberg syndrome, or a bone lesion.
- Skin changes: Discoloration, waxy texture, or hair loss overlying the indent points toward an autoimmune or dermatological cause.
- Pain or tenderness: A painful dent, especially with redness or swelling, could indicate infection, inflammation, or a cyst.
- Post-injection timing: A dip appearing weeks after a steroid or Botox injection is likely treatment-related but should be documented with the treating clinician.
- Neurological symptoms: Headaches, vision changes, numbness, or tingling alongside a forehead indent warrant prompt evaluation.
A primary care doctor can usually tell by examination and history whether the indent needs imaging. A plain X-ray can reveal bone irregularities, while a CT scan gives a detailed three-dimensional picture of the skull and soft tissue. In most cases, the workup ends with reassurance. The forehead is simply not as smooth as we expect it to be, and discovering its imperfections usually just means you finally looked closely enough to find them.