The pattern, location, and speed of your hair loss are the biggest clues to what type you have. Most hair loss falls into one of a handful of categories, and each one looks and behaves differently enough that you can often narrow it down before seeing a dermatologist. Here’s how to tell them apart.
Gradual Thinning: Pattern Hair Loss
The most common type of hair loss, by far, is androgenetic alopecia, also called male or female pattern hair loss. It affects roughly half of all men and women over their lifetimes and is driven by genetics and hormones. The hallmark is a slow, progressive thinning that follows a predictable path.
In men, the pattern usually starts at the temples and the crown of the head. You might first notice your hairline creeping back or a spot at the top getting thinner. Over time, these areas can merge, leaving hair mainly around the sides and back. Dermatologists use a 7-stage scale (the Hamilton-Norwood scale) to track progression, but you don’t need to memorize it. If your hair is receding at the temples or thinning at the crown, and it’s been happening gradually over months or years, pattern hair loss is the most likely explanation.
In women, it looks different. The hairline usually stays intact, but you’ll notice widening along your part line. Some women see a “Christmas tree” shape when they look down at their part: the thinning is widest toward the front of the scalp and narrows toward the back. Others experience a more general thinning across the entire top of the head. If you can see more scalp through your part than you used to, especially if the change has been gradual, this is the pattern to consider.
Under magnification, a dermatologist can see the telltale sign: a wide variation in hair shaft thickness. Some strands are normal while others have miniaturized into fine, wispy hairs. That mix of thick and thin is what distinguishes pattern hair loss from other types.
Sudden Shedding After a Stressor
If your hair started falling out rapidly and diffusely, with clumps in the shower drain or on your pillow, and you can trace it back to a stressful event two to three months ago, you likely have telogen effluvium. This is the second most common type of hair loss, and it’s temporary.
The trigger list is long: major surgery, high fever, significant weight loss, childbirth, stopping birth control, severe emotional stress, or a crash diet. What these all share is that they shock your body enough to push a large number of hair follicles into their resting phase at once. Those hairs then fall out together roughly two to three months later, which is why the timing between stressor and shedding is such a reliable clue.
The shedding feels alarming because it happens all over your head rather than in one spot. You might lose 200 to 300 hairs a day instead of the normal 50 to 100. But the follicles aren’t damaged. Once the underlying cause is addressed, most cases resolve within six to eight months. If you look closely, you may notice short new hairs growing in, thinner at the tip and thicker at the base, which is a sign your scalp is already recovering.
Low Iron and Vitamin D Can Fuel the Problem
Nutritional deficiencies are an underappreciated trigger for this kind of shedding. Iron levels are particularly important. A ferritin level (your body’s iron storage marker) at or below 40 µg/L is considered a red flag for hair loss even if it doesn’t meet the textbook threshold for anemia. In one study, women with telogen effluvium had average ferritin levels of just 16.3 ng/mL compared to 60.3 ng/mL in women without hair loss. Low vitamin D has also been linked to diffuse thinning. If your shedding doesn’t have an obvious trigger, a blood test checking ferritin and vitamin D is a reasonable first step.
Smooth, Round Patches: Alopecia Areata
If you’ve found one or more completely smooth, round bald patches on your scalp (or in your beard, eyebrows, or eyelashes), the likely culprit is alopecia areata. This is an autoimmune condition in which your immune system attacks hair follicles.
The patches tend to appear quickly, sometimes over just a few days, and have a distinct look: the skin inside the patch is smooth and intact, not scarred or scaly. Around the edges, you may notice very short broken hairs that are thinner at the base and wider at the top, often called “exclamation point” hairs. These are a strong diagnostic clue that points specifically to alopecia areata.
For many people, the hair regrows on its own within months. But the condition can be unpredictable. Some people experience new patches, and in more severe cases the loss can extend to the entire scalp or body. Three oral medications (JAK inhibitors) are now FDA-approved for severe alopecia areata in adults, and one is also approved for adolescents 12 and older. In clinical trials, about a third of patients with extensive hair loss achieved 80% or more scalp coverage within six to nine months of starting treatment, and results continued to improve with longer use.
Thinning Along Your Hairline From Tight Styles
Traction alopecia is hair loss caused by repeated pulling or tension on the hair. It’s most visible along the hairline and temples, where the hair is finest and most vulnerable. If you regularly wear tight braids, cornrows, locs, weaves, extensions, or slicked-back ponytails and buns, and you’ve noticed your edges receding, tension is the most likely cause.
The early warning signs are easy to miss or dismiss: pain or stinging at the scalp where the style is tightest, small bumps or crusting along the hairline, or “tenting,” where the scalp visibly lifts in sections. These are your body telling you the follicles are under stress. At this stage, the damage is reversible if you change your hairstyle. If the tension continues for months or years, the follicles can be permanently destroyed, and the hair won’t grow back.
Even constant friction from a hat, headscarf, or helmet can contribute, especially if you pull your hair back tightly underneath. The fix isn’t necessarily to stop wearing protective styles altogether. It’s to rotate styles, keep tension low, and give your hairline regular breaks.
Hair Loss With Scalp Pain or Scarring
Scarring alopecia (also called cicatricial alopecia) is the most serious category because it permanently destroys hair follicles. It’s less common than the types above, but it requires prompt attention because early treatment can prevent the damage from spreading.
The key difference from other types: the scalp itself looks and feels abnormal where hair has been lost. The skin may appear smooth and shiny, almost waxy. The tiny pore openings where hairs once emerged are visibly closed or absent. Some forms of scarring alopecia also cause redness, scaling, blistering, or pustules around the affected areas. You might feel itching, burning, or tenderness at the edges of the bald patches where active inflammation is still occurring.
In nonscarring types of hair loss (everything else on this list), the follicles are still alive even if the hair has fallen out. The scalp looks normal, and the pore openings remain visible. If your bald patches look different from the surrounding skin, or if you’re experiencing pain, burning, or unusual skin changes alongside your hair loss, that’s a signal to see a dermatologist sooner rather than later.
How Dermatologists Confirm the Diagnosis
You can narrow down the possibilities at home by considering the pattern, speed, and scalp appearance of your hair loss. But a dermatologist can confirm it with a few straightforward steps.
The pull test is one of the simplest: the doctor grasps about 40 strands of hair and tugs gently. If six or more strands come out, that indicates active shedding and points toward telogen effluvium or alopecia areata rather than the slow miniaturization of pattern hair loss.
Trichoscopy, a magnified examination of the scalp using a handheld dermatoscope, reveals details invisible to the naked eye. It can show the mix of thick and thin hairs that defines androgenetic alopecia, the short regrowing hairs that confirm telogen effluvium recovery, or the scarred and closed follicle openings of cicatricial alopecia. In some cases, a small scalp biopsy may be needed to distinguish between overlapping conditions, but most diagnoses are made from the clinical exam alone.
Quick Reference: Matching Your Symptoms
- Slow thinning at the temples, crown, or part line: Pattern hair loss (androgenetic alopecia)
- Sudden, diffuse shedding 2 to 3 months after a stressor: Telogen effluvium
- Smooth, round bald patches with intact skin: Alopecia areata
- Receding edges with a history of tight hairstyles: Traction alopecia
- Hair loss with shiny, scarred skin or pain and inflammation: Scarring alopecia