A bald spot on the back of your head most commonly results from one of a few conditions: alopecia areata (an autoimmune disorder), pattern baldness thinning at the crown, traction from tight hairstyles, or a fungal scalp infection. The cause depends on what the spot looks like, how quickly it appeared, and whether the skin itself has changed. Here’s how to tell them apart.
Alopecia Areata: Smooth, Round Patches
If your bald spot appeared suddenly and is smooth, round, and about the size of a coin, alopecia areata is the most likely explanation. This is an autoimmune condition where your immune system mistakenly attacks hair follicles, forcing them out of their growth phase prematurely. The skin in the bald area looks normal, with no redness, flaking, or scarring.
One telltale sign is “exclamation point hairs” around the edges of the patch. These are short, broken hairs that are thinner at the base and wider at the tip, like tiny exclamation marks. If you look closely or feel the border of the spot, you may notice these stubby, tapered strands. They’re a hallmark of active alopecia areata and not seen in other types of hair loss.
Triggers can include emotional or physical stress, viral infections, and certain medications, though many people never identify a clear cause. Genetics play a significant role, and the condition often runs in families alongside other autoimmune disorders like thyroid disease or vitiligo. The good news is that alopecia areata doesn’t permanently destroy the follicles, so regrowth is possible. Many people see hair return on its own within months, though patches can recur.
Treatment for a single patch often involves steroid injections directly into the spot, repeated every four to six weeks. Studies show regrowth rates of roughly 62 to 97 percent with this approach, depending on the specific treatment used. Newer oral medications that target the immune signaling pathway behind the condition are also available for more extensive cases.
Pattern Baldness at the Crown
If the thinning at the back of your head has been gradual rather than sudden, you may be seeing androgenetic alopecia, commonly called male or female pattern baldness. In men, this often starts with a receding hairline at the temples and thinning at the crown (the top-back of the head), eventually leaving a characteristic circular thin area. In women, the pattern is different: hair thins along the part line and across the top of the head, but the hairline usually stays intact.
The mechanism involves a hormone called DHT, which shrinks sensitive hair follicles over time. Each growth cycle produces a shorter, finer strand until the follicle essentially stops producing visible hair. This process is driven by genetics and tends to progress with age, though it can start as early as the late teens or twenties. Unlike alopecia areata, the thinning is gradual and diffuse rather than appearing overnight as a defined circle.
Traction Alopecia: Damage From Hairstyles
Tight hairstyles can cause localized hair loss exactly where the tension is greatest, and the back of the head is a common site. Buns, ponytails, cornrows, braids, dreadlocks, and hair extensions all pull on follicles at the occipital scalp (the lower back of the head). One case series described “chignon alopecia” in women who routinely wore their hair twisted into a tight bun at the back of the head. In a study of 143 South Korean nurses, seven developed localized hair loss at the exact spot where their caps were pinned to the back of the scalp with bobby pins, after an average of nearly 10 years of daily wear.
Traction alopecia is reversible if caught early. The follicles are still intact but inflamed from chronic pulling. If you keep using the same hairstyle for years, though, the damage can become permanent as scar tissue replaces the follicles. The first sign is often small bumps or tenderness at the site, followed by thinning and breakage.
Fungal Infection (Tinea Capitis)
If your bald spot is accompanied by redness, scaling, itching, or flaking that looks like stubborn dandruff, a fungal infection called tinea capitis could be the cause. This is more common in children but affects adults too. A characteristic clue is “black dot” tinea capitis, where infected hair shafts break right at the scalp surface, leaving tiny dark dots across the patch. The surrounding skin is often swollen and red.
In more severe cases, a painful, pus-filled, oozing lump called a kerion can form. This is an intense inflammatory reaction to the fungus and needs prompt treatment to prevent scarring. Tinea capitis requires oral antifungal medication (topical creams alone can’t reach the infection inside the hair shaft) and is typically confirmed with a scalp culture or special light examination.
Low Iron Levels and Hair Loss
Nutritional deficiencies, particularly low iron, can contribute to hair thinning and shedding. Research suggests that ferritin (the protein that stores iron) levels below 40 to 60 ng/mL may be insufficient for healthy hair growth, even when blood counts are technically normal. This is especially relevant for premenopausal women, where decreased ferritin is significantly associated with both diffuse and patterned hair loss. Iron deficiency tends to cause widespread thinning rather than a single defined patch, but it can worsen other conditions or make thinning at the crown more noticeable.
Scarring vs. Non-Scarring Hair Loss
The most important distinction is whether a bald spot involves scarring. Non-scarring types like alopecia areata, pattern baldness, and early traction alopecia leave the follicles intact, meaning hair can grow back. In scarring alopecia, the follicles are permanently replaced by scar tissue, and the skin may look shiny, smooth, or slightly discolored with no visible pore openings.
Warning signs of scarring alopecia include redness or discoloration around individual follicles, visible scaling or crusting at the follicle openings, and a burning or tender sensation. These conditions progress over time, so early identification matters. Once follicles are destroyed, the loss is permanent.
What a Scalp Exam Involves
A dermatologist can usually narrow down the cause during a single visit. The exam often includes a “pull test,” where the doctor gently grasps about 50 to 60 hairs and tugs along the shaft. If more than five or six hairs come out easily, that indicates active shedding. This test is performed across different areas of the scalp to map where the loss is most active. You’ll be asked not to wash your hair for at least 24 hours beforehand.
Many dermatologists also use a handheld magnifying device called a dermoscope to examine the scalp up close. Different conditions leave distinct signatures. Alopecia areata shows yellow dots, exclamation point hairs, and fine vellus (peach fuzz) hairs. Fungal infections show comma-shaped, corkscrew, or zigzag-shaped broken hairs that aren’t seen in alopecia areata. This simple, painless examination can often provide a diagnosis without a biopsy, though a small skin sample or fungal culture may be needed in ambiguous cases.
How to Read Your Bald Spot
A quick way to start narrowing down the cause on your own:
- Smooth, round, no symptoms: likely alopecia areata, especially if it appeared within days or weeks
- Gradual thinning at the crown: likely pattern baldness, particularly if it runs in your family
- Red, flaky, itchy, or tender: could be a fungal infection or an inflammatory/scarring condition
- Located where a hairstyle or headwear applies pressure: likely traction alopecia
- Shiny skin with no visible follicle openings: possible scarring alopecia, which needs prompt evaluation
A single small patch of alopecia areata often resolves without treatment. Pattern baldness responds to topical and oral treatments that slow or partially reverse thinning. Traction alopecia improves once you change the hairstyle. Fungal infections clear with the right medication. The key variable across all of these is time: the sooner you identify what’s happening, the more options you have.