Losing some hair every day is normal — most people shed between 50 and 100 strands daily as part of the natural growth cycle. The confusion starts when shedding increases noticeably, or when you start seeing more scalp than usual in photos or in the mirror. This guide walks through how to tell the difference, and what the most common causes actually look like.

Step 1: Is it shedding or is it hair loss?

Shedding is temporary and reverses on its own. Hair loss (alopecia) means hair is not being replaced at the same rate it falls. A simple way to check: gently pull a small section of hair (about 20-30 strands) between your fingers and pull once, firmly but not painfully. If fewer than 2-3 strands come away, that is within the normal range. If 6 or more come away consistently across several areas of the scalp, that points toward active hair loss rather than normal shedding.

Step 2: Look at the pattern

The location and shape of thinning tells you a lot before any test or doctor visit:

  • Receding hairline or thinning crown — most consistent with androgenetic alopecia (male or female pattern hair loss), especially if gradual and over years.
  • Overall thinning, no clear pattern — often linked to telogen effluvium (stress, illness, nutrition, hormonal shifts) or thyroid issues.
  • Round or oval bald patches, smooth scalp — suggests alopecia areata, an autoimmune condition, and is worth a dermatologist visit rather than home treatment (see our guides on cortisone injection treatment and the broader autoimmune disease connection).
  • Thinning concentrated along the parting or hairline under tight styles — points to traction alopecia from hairstyling or headwear tension.

Step 3: Think about timing

Hair takes 2-3 months to respond to whatever triggered a change, which is why the cause is rarely obvious right away. If your shedding started suddenly, think back 8-12 weeks: was there a fever, surgery, crash diet, major stress, new medication, or childbirth around that time? A clear trigger from that window is the single strongest clue toward telogen effluvium rather than genetic pattern loss, which tends to have no single trigger and progresses slowly over years.

The 7 most common causes

Wondering if age plays a role? See our dedicated look at hair loss specifically in your 20s if that applies to you.

1. Androgenetic alopecia (genetic pattern hair loss)

The most common cause in both men and women. Driven by genetics and sensitivity to DHT (a hormone byproduct), it follows a predictable pattern — hairline and crown in men, diffuse thinning at the part in women — and worsens gradually without treatment.

2. Telogen effluvium

A temporary, whole-scalp shedding phase triggered by physical or emotional stress, usually starting 2-3 months after the trigger and resolving within 6-9 months once the underlying cause is addressed.

3. Nutritional deficiency

Low iron, vitamin D, or protein intake can all trigger diffuse shedding. This is common in restrictive diets and in women with heavy menstrual cycles.

4. Thyroid imbalance

Both an underactive and overactive thyroid can cause diffuse hair thinning, usually alongside other symptoms like fatigue or weight changes — a blood test is the only way to confirm this.

5. Traction alopecia

Caused by consistent tension on the hair follicle from tight ponytails, braids, or headwear. It is preventable and often reversible if caught early.

6. Postpartum shedding

A specific, very common form of telogen effluvium that happens 1-4 months after childbirth as hormone levels return to baseline.

7. Alopecia areata

An autoimmune condition causing sudden, well-defined patches of hair loss. It needs a dermatologist for proper management rather than over-the-counter treatment.

When to see a dermatologist instead of self-treating

Book an appointment rather than experimenting at home if you notice: sudden patchy loss, a burning or painful scalp, redness or scaling, hair loss alongside other new symptoms (fatigue, weight change, irregular periods), or if shedding has not improved after 6 months of a clear at-home approach.

What to do next

If your pattern points to genetic hair loss, read our comparison of minoxidil, PRP, and hair transplants, or finasteride vs minoxidil if you want to compare the two most common starting treatments directly. Curious how advanced your pattern is? See the Norwood scale (for men) or Ludwig scale (for women) for the standard staging systems doctors use. If a recent stressful event lines up with your timeline, see our guide on stress-related shedding — this is also the same mechanism behind post-COVID shedding, shedding linked to rapid weight loss, and seasonal autumn shedding, if any of those sound familiar. If you're a teenager or the parent of one, our teen-specific guide covers the causes most relevant at that age. Before you spend on anything, it's also worth reading our roundup of common hair loss myths so you can filter out bad advice early. Still unsure? Our free 2-minute quiz will point you in the right direction based on your specific answers.

How a dermatologist actually diagnoses hair loss

If you do see a specialist, it helps to know what the visit typically involves, so you can prepare and know what's reasonable to expect:

  • A detailed history — timeline, family history, recent illnesses, medications, diet, and stress levels. This single conversation often narrows the likely cause more than any test.
  • A pull test, the same one described above, performed in several spots across the scalp to check how uniform or localised the shedding is.
  • Trichoscopy — a handheld magnifying device (a dermatoscope) lets the doctor examine individual follicles and hair shaft diameter up close, which can distinguish miniaturising genetic hair loss from other patterns long before it's obvious to the naked eye.
  • Bloodwork, when a non-genetic cause is suspected — typically ferritin, TSH, and sometimes vitamin D or a full blood count, rather than a single generic "hair loss panel."
  • A scalp biopsy, reserved for unclear or scarring cases where the pattern doesn't fit the common categories — this is the exception, not the norm, for most people walking in with ordinary thinning.

A simple 4-week self-tracking framework

Before or alongside seeing anyone, this structure makes your own observations far more useful than vague impressions:

  1. Week 1: Take a well-lit photo of your hairline, crown, and a general front-on shot. Do the pull test in three different areas and note the result.
  2. Week 1: Write down anything from the past 3 months that could be a trigger — illness, diet changes, new medications, major stress, childbirth.
  3. Weeks 2-3: Note roughly how much hair you're seeing in the shower or on your pillow — "noticeably more than usual," "about the same," or "less" is precise enough; exact counting isn't necessary and tends to increase anxiety without adding useful information.
  4. Week 4: Retake the same photos from week 1, same lighting and angle. Compare side by side.

This single month of structured observation, more than any single test, usually makes the difference between "I think it's getting worse" and an actual, comparable answer — and it's exactly the kind of information that makes a doctor's visit far more productive if you do go.

Two free tools to help you track this properly

Rather than relying on memory, try our hair shedding checker to assess whether your current shedding level is normal or worth investigating, and our hair loss risk calculator to understand your broader genetic and lifestyle risk profile.

A note on patience with the diagnostic process

It's genuinely common to go through more than one of the causes above before landing on the right explanation — a stressful period might coincide with the start of genetic thinning, or a nutritional gap might compound a hormonal shedding phase already underway. This overlap is normal, not a sign you're doing the self-assessment wrong.