A bald line on your scalp is almost always caused by one of a handful of conditions, and the most likely culprit depends on where the line is, how it appeared, and whether you have any other symptoms like itching or redness. The most common causes include traction from tight hairstyles, a band-like pattern of autoimmune hair loss called ophiasis, scarring from an old injury, or an inflammatory scalp condition. Most of these are treatable, and some resolve on their own.
Traction From Tight Hairstyles
If the bald line follows the path of a part, braid, or area where your hair is regularly pulled tight, traction alopecia is the most likely explanation. This type of hair loss results from continuous pulling on the hair roots over time. Cornrows, tight ponytails, weaves, braids, and even turbans can all create enough mechanical stress to damage follicles along specific lines on the scalp.
The pattern of hair loss directly maps to the areas under tension. That’s why traction alopecia often produces linear, curved, or geometric bald patches rather than random round spots. It commonly starts near the temples and above the ears but can appear anywhere the hairstyle pulls hardest. Early on, the hair loss is reversible if you reduce the tension. If it continues for years, the follicles can scar over and the loss becomes permanent.
Ophiasis: Band-Like Autoimmune Hair Loss
Ophiasis is a specific subtype of alopecia areata, an autoimmune condition where the immune system mistakenly attacks hair follicles. Unlike the more common round patches of alopecia areata, ophiasis creates a band-like strip of hair loss that wraps around the back and sides of the head, extending from the lower scalp toward the temples. The result looks like a distinct bald line running through otherwise normal hair.
The onset is usually sudden, and the skin in the bald area looks smooth because the follicles themselves aren’t destroyed, just temporarily shut down by inflammation. The exact cause is unknown, though genetics and environmental triggers like viral infections likely play a role. Ophiasis can be stubborn to treat compared to patchy alopecia areata, but steroid injections into the affected area produce significant regrowth in many cases. Studies show that 54% to 87% of patients with localized alopecia areata achieve more than 75% regrowth with this approach, though about one in four people experience recurrence after stopping treatment.
Scars From Injury or Surgery
If the bald line has been there for as long as you can remember, or appeared after an injury, it may be a scar. When the scalp is cut, burned, or damaged deeply enough, the hair follicles in that area are destroyed and replaced with scar tissue. The skin in these spots typically looks smooth, shiny, and slightly different in texture from the surrounding scalp. No hair will grow from scarred follicles on its own, though surgical hair transplantation can sometimes restore coverage.
Some people discover childhood scars they never knew about, especially from falls or minor procedures. If the line is narrow, straight, and the skin feels slightly firmer or smoother than the rest of your scalp, a scar is a strong possibility.
Inflammatory Scalp Conditions
Lichen planopilaris is an inflammatory condition that causes scarring hair loss on the scalp. It destroys follicles permanently, leaving behind smooth bald patches that can sometimes follow a linear pattern. Unlike alopecia areata, which is painless, lichen planopilaris often comes with noticeable symptoms: itching, burning, scalp pain, and red or scaly patches of skin around the affected area.
A related condition called frontal fibrosing alopecia creates a receding band of hair loss along the forehead hairline. This recession is usually symmetric and progresses slowly, moving backward at roughly 0.2 to 2.1 centimeters per year without treatment. It can also cause eyebrow and eyelash thinning. If you’ve noticed your hairline creeping back in a uniform line, especially with any scalp discomfort, this is worth investigating early because the hair loss is permanent once it occurs.
Hair Pulling Habits
Trichotillomania, a hair-pulling disorder, can create linear bald spots if you tend to pull hair along a specific path. Many people with this condition develop rituals around how and where they pull, sometimes targeting the same area repeatedly. The result can look like a bald line or strip rather than a random patch. Shortened, broken hairs of uneven length around the edges of the bald area are a telltale sign.
Some people pull hair without fully realizing it, especially while reading, watching TV, or resting their head on one hand. If the bald line is in a spot you can easily reach during these activities, it’s worth paying attention to whether you might be pulling without noticing.
Widening Hair Part
Sometimes what looks like a bald line is actually a widening hair part. If you’ve worn the same part for years, the hair along that line can thin gradually from a combination of sun exposure, repeated styling stress, and natural hair miniaturization. There’s no universally agreed-upon measurement for a “normal” part width, but some hair researchers consider a part wider than 1 centimeter to be a sign of patterned hair loss. If your part has been slowly getting wider rather than appearing suddenly, this is more likely diffuse thinning or early pattern hair loss than a distinct condition.
How to Tell What’s Causing Yours
A few details can help you narrow down the cause before you see a dermatologist. Location matters: a line along the back and sides of the head suggests ophiasis, while thinning at the temples or along braid lines points to traction. A receding band at the forehead suggests frontal fibrosing alopecia. A fixed line that hasn’t changed in years is likely a scar.
Symptoms matter too. Pain, itching, or burning suggest an inflammatory condition like lichen planopilaris. Smooth, painless skin with no redness is more typical of alopecia areata or an old scar. Broken hairs of different lengths around the edges may indicate pulling behavior or a fungal infection.
Speed of onset is another clue. Alopecia areata appears suddenly, sometimes within days. Traction alopecia and frontal fibrosing alopecia develop over months to years. A dermatologist can examine the bald area with a magnifying instrument to look for specific signs: tiny “exclamation mark” hairs (short hairs that taper at the base) are a hallmark of alopecia areata, while scaling around follicles can indicate a fungal infection. These details are difficult to spot on your own but make diagnosis much more straightforward for a specialist.
The good news is that many causes of a bald line are treatable, especially when caught early. Even conditions like alopecia areata, where the immune system is involved, often respond well to treatment or resolve on their own within several months.