Telogen Effluvium, Androgenetic Alopecia, Alopecia Areata: Patterns and Triggers

How do dermatologists distinguish stress shedding, pattern thinning, and patchy autoimmune loss?

Disclaimer: This article provides general educational information and is not medical advice. It does not replace a diagnosis, treatment, or personalized guidance from your own clinician.

You are not imagining your hair changes. You deserve clear answers and a calm plan. I will walk you through the three most common non-scarring hair loss patterns, how dermatologists tell them apart, and what you can do today while you organize care.

What are the “big three” hair loss patterns?

Dermatologists group most non-scarring hair loss into three buckets: telogen effluvium, androgenetic alopecia, and alopecia areata. Each has a different mechanism, tempo, and treatment.

• Telogen effluvium (TE) means temporary, diffuse shedding after a body stressor such as illness, surgery, high fever, postpartum change, iron deficiency, crash dieting, or major psychological stress. Shedding often starts two to three months after the trigger and usually settles within three to six months as the body resets.¹²⁵

• Androgenetic alopecia (AGA) means pattern hair loss driven by genes and androgen signaling. It shows a gradual, predictable pattern over years, with miniaturization of follicles. It affects up to half of men and women across a lifetime.⁴

• Alopecia areata (AA) means autoimmune attack on hair follicles that causes sharply defined patches, sometimes with “exclamation mark” hairs and nail pitting. Disease can be patchy or extensive, and it can recur.⁵⁷

How do these conditions feel and look different day to day?

Your story guides the diagnosis. Dermatologists listen for onset, triggers, pattern, and symptoms, then examine the scalp and sometimes perform tests.

• TE feels like sudden excess shedding. You may see more hair in the shower or brush. A hair-pull test is often positive during active shedding and draws more than 10 percent of grabbed hairs.⁵¹⁰

• AGA feels like slow thinning. You may notice a widening part, frontal recession, or vertex thinning without large clumps of hair in the drain. A hair-pull test is usually negative away from visibly thin areas.¹⁰

• AA feels like a patch appears. You may see a smooth, round bald spot with “stubby” broken hairs at the rim. A hair-pull test at the edge is often positive.⁵

Quick comparison table you can skim

Clue	Telogen effluvium	Androgenetic alopecia	Alopecia areata
Onset	Abrupt shedding 2–3 months after a trigger; lasts 3–6 months²	Gradual over years⁴	Sudden patch or patches; any age⁵
Pattern	Diffuse thinning across scalp²	Patterned thinning: frontotemporal and vertex in men; mid-scalp widening in women⁴	Well-defined round or oval patches; sometimes brows/lashes⁵
Hair-pull test	Often positive during active shed¹⁰	Usually negative away from thin zones¹⁰	Often positive at patch border⁵
Trichoscopy	Many club hairs; no scarring	Hair-diameter diversity at or above 20 percent; increased vellus hairs⁶	Yellow dots, black dots, broken and exclamation hairs⁷
Common triggers	Illness, fever, surgery, postpartum change, crash diet, iron deficiency²⁵	Genetics and androgens⁴	Autoimmune predisposition; sometimes stress or infection precedes⁵
Prognosis	Regrowth expected after trigger resolves; full volume returns over months¹	Chronic but controllable with ongoing treatment⁴	Variable; many patches regrow, some cases recur or become extensive⁵
First-line medical options	Address trigger; correct deficiencies²	Topical minoxidil; finasteride for eligible adults; other options per clinician³⁸¹²	Intralesional corticosteroids for patches; for severe cases, FDA-approved oral JAK inhibitors in select patients⁸⁹

*Notes: exclamation mark hairs are short hairs tapered at the root; club hairs are shed hairs with keratin bulbs visible at one end.*⁵

Why does timing matter so much?

Hair cycles create a delay between cause and effect. In TE, a stressor pushes many follicles from growth into rest; the shed starts weeks later. That is why postpartum or post-illness shedding often appears after a quiet period. Most people recover as the stress resolves, and fullness improves over six to nine months.¹²⁴

How do dermatologists examine the scalp?

We combine simple bedside tests with magnified inspection. A hair-pull test samples 40 to 60 hairs per site; more than 10 percent release suggests active shedding.¹⁰ In trichoscopy, we look for signature patterns: in AGA, hair-diameter diversity and more vellus hairs; in AA, yellow dots, black dots, broken and tapered hairs.⁶⁷ These clues help avoid unnecessary biopsies.

Which blood tests are reasonable?

Testing should match the story. For diffuse shedding or suspected TE, many clinicians check ferritin and thyroid function, and consider a complete blood count or vitamin D depending on symptoms and risk. NICE Clinical Knowledge Summaries advise ferritin and thyroid testing when TE is suspected.¹³ A focused panel can find correctable causes without over-testing.

What treatments work, and when?

Treatments follow the diagnosis, not the other way around.

Telogen effluvium: how to calm a shedding phase

• Identify and reverse the trigger when possible. Correct iron deficiency, optimize thyroid health, recover nutrition, and reduce physical and mental stress where you can.²⁵

• Practice gentle scalp care while follicles reset. Use a fragrance-free cleanser and lukewarm water. The American Academy of Dermatology advises simple, gentle routines tailored to scalp oiliness and flaking.¹¹

• Choose a soothing wash duo: On non-medicated days, wash with The Better Scalp Company Sensitive Scalp Shampoo, then condition lengths with Sensitive Scalp Conditioner to reduce friction at comb-out.

• Expect regrowth. Most TE episodes settle within three to six months, with new growth peaking in the months that follow.²

Androgenetic alopecia: how to slow and thicken

• Use topical minoxidil consistently. This remains the most recommended first-line therapy for female pattern hair loss, with 2 percent and 5 percent strengths available.³

• Discuss finasteride if you are an adult candidate. Finasteride is FDA approved for men; other antiandrogen strategies in women are specialist-guided.³¹²

• Consider adjuncts if needed. Dermatologists individualize plans that may include low-dose oral minoxidil or other options after risk–benefit discussion.³¹²

• Commit to maintenance. AGA is chronic; gains persist only while treatment continues.³

Alopecia areata: how to quiet autoimmune activity

• Treat patches early with in-office corticosteroid injections where appropriate.⁵

• Escalate in severe disease with systemic options when indicated. The FDA approved baricitinib in 2022 as the first systemic therapy for adults with severe AA, and ritlecitinib in 2023 for adults and adolescents 12 years and older with severe AA.⁸⁹

• Support regrowth with gentle care to protect fragile regrowing hairs and brows. Fragrance-free cleansers reduce irritant contact while skin is reactive.¹¹

Which at-home steps actually help right now?

You can support your scalp today while you arrange care.

• Switch to fragrance-free basics. Fragrance is a common irritant. Use The Better Scalp Company Sensitive Scalp Shampoo and Sensitive Scalp Conditioner to cleanse the scalp and protect hair fiber during detangling.¹¹

• Match wash frequency to your scalp. Oily scalps often do better with more frequent gentle washing; dry scalps can space washes and condition lengths carefully.¹¹

• Be kind to follicles. Avoid tight styles, high heat, and vigorous brushing on wet hair.

• Time medicated shampoos. When your clinician recommends a medicated shampoo for dandruff or seborrheic dermatitis, let it sit for the labeled contact time before rinsing.¹⁶

• Organize your notes. Write down timing of onset, any illness, childbirth, surgery, weight change, new medications or supplements, and family history. Bring photos if you have them.

When should you see a dermatologist?

Book an appointment if:

• Shedding is severe, lasts longer than three to six months, or recurs.²

• You see expanding patches, eyebrow or eyelash loss, or nail changes.⁵

• You have scalp pain, burning, or visible redness or scale that does not settle with gentle care.

• You want to start AGA therapies or discuss systemic options for AA.³⁸⁹

Early evaluation shortens uncertainty and protects follicles while treatment options are still broad.

What will the visit likely include?

Expect a focused consult. Your dermatologist will take a detailed history, examine hair and scalp, perform hair-pull tests, and may use trichoscopy. Laboratory tests are ordered when the story points to TE or another medical trigger.¹¹¹³ Targeted testing avoids delays and helps direct a precise plan.

Gentle routine you can start tonight

Evening routine

1. Cleanse the scalp with The Better Scalp Company Sensitive Scalp Shampoo. Massage with fingertips for 60 seconds. Rinse with lukewarm water.

2. Condition mid-lengths to ends with Sensitive Scalp Conditioner. Detangle with a wide-tooth comb.

3. Blot with a microfiber towel. Air dry or use the coolest setting.

Morning routine

1. Style loosely and avoid tugging at the hairline.

2. If using topical minoxidil for AGA, apply to dry scalp as directed, then wash hands.³

This routine protects the scalp barrier while you work with your clinician on diagnosis and treatment.

Frequently asked questions

Can heavy shedding still be TE if it has lasted four months?

Yes. TE can shed briskly for several months and then slow, often resolving by six months once the trigger has passed.² If shedding persists beyond six months, clinicians reassess for chronic TE, overlapping AGA, or another cause.

Can TE and AGA happen together?

Yes. A pattern hair loss baseline can be unmasked by a TE episode. Dermatologists treat the TE trigger and start maintenance therapy for AGA at the same time when appropriate.³⁴⁶

Do I need a biopsy?

Usually not. History, exam, hair-pull testing, and trichoscopy are often enough. Biopsy is reserved for unclear cases or when scarring alopecia is suspected.¹¹

Bottom line

You can map what you are feeling to a real pattern and a plan. Sudden diffuse shedding points to telogen effluvium, slow patterned thinning points to androgenetic alopecia, and sharply defined patches point to alopecia areata. Good outcomes start with a careful story, a gentle routine, and timely, evidence-based treatment.

You are not alone in this. Early steps protect follicles, and most people do far better than they fear.

Glossary

• Telogen effluvium: Temporary diffuse hair shedding that follows a stressor and begins weeks later.²

• Androgenetic alopecia: Genetic and hormone-influenced pattern hair loss with gradual miniaturization.⁴

• Alopecia areata: Autoimmune patchy hair loss that may affect any hair-bearing site.⁵

• Hair-pull test: Bedside test that gently tugs 40–60 hairs; more than 10 percent release suggests active shedding.¹⁰

• Trichoscopy: Dermatoscope-assisted evaluation of hair shafts and follicles to identify diagnostic patterns.⁶⁷

• Vellus hair: Fine, short, light hair that increases as follicles miniaturize in AGA.⁶

• Club hair: Shed hair with a keratin bulb characteristic of the telogen phase.⁵

• Yellow dots/black dots: Trichoscopic signs seen in alopecia areata.⁷

Claims Registry

Citation #	Claim(s) supported	Source title + authors + year + venue	Accessed date (America/New_York)	Anchor extract	Notes
1	TE often resolves as the stressor abates and fullness returns over 6–9 months	“Do you have hair loss or hair shedding?” American Academy of Dermatology, 2024	2025-11-20	“Within six to nine months, the hair tends to regains its normal fullness.”	Authoritative patient guidance from AAD
2	TE begins about 2–3 months after a trigger and lasts 3–6 months	“Telogen Effluvium,” Cleveland Clinic, 2022	2025-11-20	“Acute telogen effluvium lasts fewer than six months… happens two to three months after a stressor.”	Academic medical center
3	Minoxidil is the most recommended first-line therapy for female pattern hair loss; 2% and 5% approved	“Could it be female pattern hair loss?” AAD, 2022	2025-11-20	“Products containing either 2% or 5% minoxidil have been approved… Today, it is the most-recommended treatment for FPHL.”	AAD patient guidance
4	AGA definition, prevalence up to 50 percent, and typical patterns	“Androgenetic Alopecia,” StatPearls, Ho et al., 2024	2025-11-20	“Affects up to 50 percent of males and females… most prominent in the vertex and frontotemporal regions in males.”	Peer-reviewed clinical review on NCBI
5	AA hallmark features; hair-pull often positive; patchy presentation	“Alopecia Areata,” DermNet NZ, 2023	2025-11-20	“Features… include exclamation point hairs… Hair pull test… often positive in alopecia areata.”	Dermatology reference
6	Trichoscopy criteria in AGA include hair-diameter diversity ≥20 percent	“Trichoscopy of generalised noncicatricial hair loss,” DermNet NZ, 2023	2025-11-20	“Hair shaft thickness diversity… a diversity ≥20% is diagnostic of androgenetic alopecia.”	Dermatology reference
7	Trichoscopic signs of AA include yellow dots, black dots, broken and tapering hairs	“Trichoscopy pattern in alopecia areata: A systematic review,” Al-Dhubaibi et al., 2023, Dermatologic Therapy (PMC)	2025-11-20	“Five most characteristic… yellow dots, black dots, broken hairs, short vellus hairs, and tapering hairs.”	Systematic review
8	FDA approved baricitinib in 2022 as first systemic treatment for severe AA in adults	“New Drug Therapy Approvals 2022,” FDA CDER	2025-11-20	“Olumiant was also approved in 2022 to treat adults with severe alopecia areata… first CDER approval of a systemic treatment for alopecia.”	Primary regulator
9	FDA approved ritlecitinib in 2023 for severe AA in adults and adolescents 12+	FDA NDA Approval Letter for LITFULO (ritlecitinib), 2023	2025-11-20	“Approved… for the treatment of severe alopecia areata… in adults and adolescents 12 years and older.”	Primary regulator
10	Hair-pull test method and positive threshold >10 percent	“Hair Loss: Common Causes and Treatment,” Phillips et al., 2017, American Family Physician	2025-11-20	“A positive result is when more than 10% of hairs… are pulled… suggests telogen effluvium… or alopecia areata.”	Family medicine clinical review