Hair Loss: Causes, Diagnosis,
and Treatment

Losing 50 to 100 hairs a day is normal. Losing more than that, seeing a widening part, a receding hairline, bare patches, or hair that no longer grows back is hair loss, and it has a cause that can usually be identified. The most common causes are hereditary pattern hair loss, temporary shedding after a stress on the body, and the autoimmune condition alopecia areata. Each is treated differently, which is why an accurate diagnosis comes first. Belaray Dermatology evaluates and treats hair loss in adults and children at its Hicksville and Stony Brook offices.

Why Am I Losing My Hair?

Hair grows in cycles. Each follicle grows for several years, rests for a few months, sheds, and starts again. Hair loss happens when follicles shrink, when too many enter the resting phase at once, when the immune system attacks them, or when they are destroyed by inflammation or injury. The main types are:

• Androgenetic alopecia (pattern hair loss) is the most common cause, affecting an estimated 80 million men and women in the United States. In men it shows as a receding hairline and thinning crown; in women as a widening part and overall thinning on top while the hairline is preserved. It is hereditary and driven by the effect of androgens on genetically sensitive follicles, which gradually shrink.
• Telogen effluvium (shedding) is sudden, diffuse shedding that begins two to three months after a stress on the body: childbirth, surgery, high fever or illness, rapid weight loss, a new medication, iron deficiency, or thyroid disease. Handfuls of hair come out in the shower and on the pillow. It usually resolves on its own once the trigger has passed.
• Alopecia areata is an autoimmune condition that causes smooth, round, bare patches, sometimes with tiny “exclamation point” hairs at the edges. It can affect the scalp, beard, eyebrows, or eyelashes and may come and go. It affects about 2 percent of people at some point in their lives.
• Traction alopecia comes from hairstyles that pull for long periods: tight braids, ponytails, extensions, and weaves. It is reversible early and permanent if the pulling continues.
• Scarring (cicatricial) alopecias, such as lichen planopilaris, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia, destroy the follicle with inflammation. The scalp may be itchy, tender, red, or scaly. Hair lost to scarring does not regrow, so early treatment matters most here.
• Other causes include fungal infection of the scalp (tinea capitis, common in children), hair-pulling (trichotillomania), chemotherapy, and nutritional deficiencies.

How Is Hair Loss Diagnosed?

A dermatologist can usually identify the type at the first visit. The evaluation includes:

• Your history: when the loss started, how fast, family history, recent illness, pregnancy, diet, hairstyling habits, and every medication and supplement.
• A scalp examination with dermoscopy (a handheld magnifier) to look at follicle openings, hair-shaft thickness, scale, and redness. This distinguishes pattern loss from shedding and from scarring in most cases.
• A pull test to measure active shedding.
• Blood tests when indicated: a blood count, ferritin (iron stores), thyroid function, vitamin D, and in women with irregular periods or acne, hormone levels.
• A scalp biopsy when scarring alopecia is suspected or the pattern is unclear. It is a small, quick, in-office procedure under local anesthesia.

What Treatments Are Available?

Treatment depends on the type. Here is what works for each.

Pattern Hair Loss (Androgenetic Alopecia)

• Topical minoxidil (5 percent) is available over the counter as a foam or solution and works for men and women. It prolongs the growth phase and thickens miniaturized hairs. Expect a temporary increase in shedding during the first weeks, visible results after three to six months, and continued use to maintain them.
• Low-dose oral minoxidil is a prescription option used off-label that many patients find easier to stick with than daily topical application. It is monitored by your dermatologist.
• Finasteride is a daily prescription pill for men that blocks the hormone that shrinks follicles. It slows loss in most men and regrows hair in many. It is not used in women who could become pregnant.
• Spironolactone is a prescription option used off-label in women, especially when hormonal factors contribute.
• Platelet-rich plasma (PRP) uses growth factors from your own blood, injected into the scalp in a series of sessions, to stimulate follicles. It is offered at Belaray as an add-on to medical treatment.
• Low-level laser devices (caps and combs) have modest supporting evidence and can be combined with the options above.

Shedding (Telogen Effluvium)

The treatment is finding and correcting the trigger: replacing iron, treating the thyroid, adjusting a medication, or simply allowing time after childbirth or illness. Shedding typically slows within three to six months, and regrowth follows. Minoxidil can speed recovery when shedding is prolonged.

Alopecia Areata

Small patches often respond to cortisone injections into the affected skin, repeated every four to six weeks, or to prescription-strength topical steroids. Topical minoxidil supports regrowth. For extensive or rapidly progressing disease, newer oral JAK inhibitors (baricitinib for adults, ritlecitinib for ages 12 and up, and deuruxolitinib) are FDA-approved and can regrow hair in patients who previously had few options. These are prescribed and monitored by a dermatologist.

Scarring Alopecias

The goal is to stop the inflammation before more follicles are destroyed. Treatment may include cortisone injections, potent topical steroids, and oral anti-inflammatory medications such as doxycycline or hydroxychloroquine. Because lost follicles do not regrow, these conditions should be evaluated as soon as symptoms such as scalp itching, burning, tenderness, or shiny bare areas appear.

Traction Alopecia

Loosen or change the hairstyle. Early traction loss regrows over months; minoxidil can help. Long-standing traction loss becomes scarring and permanent.

What Results Can I Expect?

Hair grows about half an inch a month, so every treatment needs at least three to six months before results are judged, and most medical treatments for pattern loss have to be continued to keep the benefit. A photo taken at the first visit and again at each follow-up is the most reliable way to track progress. The earlier treatment starts, the more hair there is to preserve.

Does Insurance Cover Hair Loss Treatment?

The evaluation, blood tests, scalp biopsy, cortisone injections, and prescription medications for medical hair loss are generally covered as medical care. PRP and low-level laser devices are considered cosmetic and are paid out of pocket. Visits and prescriptions are eligible expenses for a flexible spending or health savings account; see our FSA and HSA guide.

When Should I See a Dermatologist?

• Sudden or heavy shedding, especially handfuls of hair.
• Bare patches, or loss of eyebrows, eyelashes, or beard hair.
• Scalp itching, burning, pain, redness, scaling, or pustules along with hair loss.
• A widening part, receding hairline, or thinning that is bothering you. The earlier pattern loss is treated, the better the result.
• Hair loss in a woman together with irregular periods, acne, or facial hair, which can point to a hormonal cause.
• Hair loss in a child, which is often tinea capitis or alopecia areata and is very treatable.

Frequently Asked Questions

Is losing 100 hairs a day normal?

Yes. Shedding 50 to 100 hairs a day is part of the normal hair cycle, in which each follicle grows, rests, and sheds before starting again. Shedding becomes hair loss when it clearly exceeds that, when the hair does not grow back, or when you notice thinning, a widening part, a receding hairline, or bare patches.

Can hair grow back after hair loss?

It depends on the cause. Shedding after illness, childbirth, or stress usually regrows fully once the trigger has passed. Alopecia areata patches often regrow with treatment. Pattern hair loss can be slowed and partly reversed with minoxidil, finasteride, or spironolactone, and traction loss regrows if caught early. Hair lost to scarring alopecia does not regrow, which is why scalp inflammation should be evaluated promptly.

Does minoxidil work, and do I have to keep using it?

Yes, topical 5 percent minoxidil works for most men and women with pattern hair loss, thickening fine hairs and slowing further loss. Results appear after three to six months, sometimes after a temporary increase in shedding. The benefit lasts only as long as you keep using it; stopping returns the hair to its previous course within a few months. Low-dose oral minoxidil is a prescription alternative.

What blood tests check for hair loss?

When the history or exam suggests it, a dermatologist may order a complete blood count, ferritin to measure iron stores, thyroid function tests, vitamin D, and, in women with irregular periods or acne, hormone levels. Many patients with pattern hair loss or alopecia areata need no blood work at all, because the diagnosis is made by examining the scalp.

Is hair loss a sign of a thyroid problem?

It can be. Both an underactive and an overactive thyroid can cause diffuse shedding, usually along with other symptoms such as fatigue, weight change, or feeling too cold or too hot. Thyroid-related hair loss improves once the thyroid is treated, although regrowth takes several months. A simple blood test checks thyroid function.

Does PRP work for hair loss?

Platelet-rich plasma can thicken hair in pattern hair loss by delivering growth factors from your own blood to the follicles, and research supports a modest benefit when it is given as a series of sessions and maintained. It works best alongside medical treatment such as minoxidil, not instead of it. PRP is considered cosmetic and is not covered by insurance.

Can stress cause hair loss?

Yes. A major physical or emotional stress can push a large share of follicles into the resting phase at once, causing noticeable shedding two to three months later. This is called telogen effluvium. It is temporary in most cases, and the hair regrows over several months once the stress has passed. Stress can also trigger flares of alopecia areata in people who are prone to it.

Related reading: PRP for hair growth, dandruff vs. seborrheic dermatitis vs. scalp psoriasis, psoriasis treatment (scalp psoriasis is a common cause of scalp scaling), our FSA and HSA guide, and the patient education hub.