Hair Loss: What Causes It? A Dermatologist Explains 5 Types — Which Resolve on Their Own and Which Become Permanent If Left Untreated
Hair loss (alopecia) is shedding of more than 100 hairs a day for several days in a row, or thinning to the point that the scalp shows more clearly. It is not a single disease but a symptom of at least 5 groups of conditions with different causes and very different treatments. The most common cause in Thai patients is telogen effluvium after illness or stress, which resolves on its own within 3–6 months, followed by genetic and hormonal thinning (androgenetic alopecia), which does not resolve on its own and gradually becomes permanent without treatment.
This article covers all 5 types, with the actual medications used for each, their strengths, how long they must be used before judging the result, and the side effects to know in advance, because what costs patients months is not failing to know "what causes hair loss" but being treated for the wrong type.
How many hairs a day is abnormal?
A normal scalp has about 100,000 hairs, and each hair follows its own cycle. Around 85–90% are in the growth phase (anagen), which lasts 2–6 years, and about 10–15% are in the resting phase (telogen), which lasts 2–3 months before the hair falls out. Shedding 50–100 resting hairs a day is therefore normal and not a disease.
The criteria used in the clinic are three.
Count: shedding of more than 100 hairs a day for more than 2 weeks in a row is abnormal. On a wash day, shedding of up to 150–200 hairs is still explainable, because washing collects several days' worth of loose hairs at once.
Look at density: heavy shedding with unchanged density is usually temporary. Less shedding but a part line that keeps widening is more concerning, because it means the new hairs are coming in smaller than the ones they replace.
Hair pull test: the doctor grasps about 60 hairs and pulls gently. If more than 6 come out in the hand (more than 10%), the test is positive, indicating active shedding rather than just a feeling.
A practical way to count at home is to collect all the hair shed in a day, from the pillow, the bathroom and the comb, into a separate bag each day for 7 days in a row, then work out the average. Counting a single day is misleading, because wash days and non-wash days differ several-fold.
Hair shedding and hair thinning are not the same, and they are treated differently
This is the point patients misunderstand most often, and the reason many buy several bottles of shampoo with no improvement.
Shedding is fully grown hairs falling out together in large numbers. The fallen hair has a small white bulb at the root and is as long as normal hair. It is a situation in which "the trigger is over and the hair is catching up", and most cases recover on their own.
Thinning (miniaturization) is hair that gets progressively finer, shorter and lighter with each growth cycle until it becomes vellus (fine, downy) hair. The fallen hairs are often shorter and thinner than normal. This does not resolve on its own, and the period when the follicle is not yet completely dead is the only time medication works well.
In practice, if combing brings out many long, thick hairs, temporary shedding is more likely. But if a photo of your center part compared with a photo from last year shows a wider part, that is thinning, which needs medication to be started rather than waiting to see. The difference matters a great deal, because medication for genetic thinning does nothing for telogen effluvium, and waiting for thinning to resolve on its own means losing follicles all the while.
The 5 types of hair loss to tell apart before starting medication
Treating hair loss starts with one question: are the follicles still there or already gone? If the follicle is still present, hair can grow back. If the follicle has been replaced by scar tissue, no medication can bring it back. The following five types are ordered from the most common to the most urgent.
Type 1: Telogen effluvium
Appearance: heavy, even shedding over the whole scalp, usually 150–400 hairs a day, most noticeable when washing and combing. The fallen hairs are normal-length with a white bulb at the root. Overall density drops, but there are no bald patches and no part widening in one spot.
Cause: the body meets a trigger and pushes a large number of hairs into the resting phase at once. Common triggers are high fever or severe infection, surgery, childbirth, rapid weight loss or crash dieting, iron deficiency, thyroid disease, severe stress, and starting or stopping certain medications. The key point is that the trigger happens about 2–3 months before the shedding, so patients often cannot think of a cause, because by the time the hair falls they have already recovered.
Severity/urgency: not urgent. Every follicle is intact. Once the trigger is gone, shedding stops within 3–6 months and density returns to baseline within 6–12 months. Shedding that continues beyond 6 months is called the chronic form, and a hidden cause needs to be looked for.
When to see a doctor: when shedding continues for more than 3 months and no trigger can be found, when there are other symptoms such as fatigue, heavy periods or weight change, or when the part starts to widen, which means genetic thinning is hiding underneath.
What treats this condition is not a hair supplement but correcting the underlying cause, such as replacing iron when it is truly low, adjusting thyroid medication into range, or correcting a nutritional deficiency. While waiting, care for the hair as usual and do not stop washing it for fear of shedding. Not washing does not reduce the number of hairs that fall out; it only postpones them so they fall out together on a later day.
Type 2: Genetic and hormonal thinning (Androgenetic alopecia)
Appearance: in men it starts with both sides of the forehead receding deeply into an M shape, followed by the crown. In women it usually starts at the center part, which slowly widens like a Christmas tree, while the front hairline is usually preserved. The hallmark is that hairs in the area vary in size, a mix of thick hairs and small vellus-like hairs.
Cause: follicles in hormone-sensitive areas are affected by the hormone DHT (dihydrotestosterone), which is converted from testosterone by the enzyme 5-alpha reductase. The growth phase gets shorter with every cycle, so the hair gets finer and finer until it becomes vellus hair and finally stops growing. This sensitivity to DHT is inherited.
Severity/urgency: not dangerous to health, but it is the only one of the five types where "the longer you wait, the more you lose", because once the follicle has fully atrophied, medication cannot bring it back. The period when treatment works best is while vellus hairs are still visible in the area.
When to see a doctor: as soon as you notice a wider part or a receding hairline compared with old photos. Do not wait until the scalp is clearly visible, because starting medication early gives a significantly different result than starting late.
This is the type in which minoxidil and finasteride act directly. Details of their use are in the medication sections below, and for an in-depth article on this topic alone, see Genetic Hair Loss (Androgenetic Alopecia)
Type 3: Patchy round hair loss (Alopecia areata)
Appearance: bald patches with smooth edges, round or oval. The skin in the patch is smooth, not red, not scaly, not scarred, and follicle openings are still visible. Short hairs that widen at the tip, like exclamation marks, may be seen at the edge of the patch. Some patients also lose eyebrows, beard or eyelashes, and may have small pits in the nails.
Cause: the immune system mistakenly attacks the person's own hair follicles. It can occur together with other autoimmune conditions such as autoimmune thyroiditis, vitiligo and atopic dermatitis.
Severity/urgency: the follicles do not die, so hair can grow back even after a long time. About 50% of single-patch cases resolve on their own within 1 year. But if it spreads quickly, involves multiple patches, starts before adolescence, or extends to the hairline at the back of the head, the outlook is worse and treatment should start early.
When to see a doctor: as soon as you see a bald patch with a clear edge, because it must always be distinguished from scalp ringworm and scarring hair loss. If the patch has scale, redness or pustules, think of scalp ringworm (tinea capitis), which needs an oral antifungal, not a topical steroid.
Full details on diagnosis and treatment options are in the article Patchy Hair Loss (Alopecia Areata)
Type 4: Traction alopecia
Appearance: thinning along the line that is regularly pulled, most often at both temples and the front hairline. A characteristic sign is a single row of small hairs left right next to the original hairline. In the early stage there may be red bumps around the follicles, or scalp pain when the hair is tied back.
Cause: constant pulling on the follicles from tight ponytails, tight braids, hair extensions, and regular use of tight clips or hats, together with chemical perming or straightening that makes the hair brittle.
Severity/urgency: in the early stage it is fully reversible if the pulling stops, but if left for years it becomes permanent scarring. The line between "recoverable" and "not recoverable" is whether follicle openings can still be seen in the area.
When to see a doctor: when 3 months after stopping the pulling hairstyle the hair still has not returned, or when the skin in the area starts to look smooth and shiny so that follicle openings cannot be seen.
Type 5: Scarring alopecia
Appearance: bald patches where the skin is smooth and shiny with no visible follicle openings. The edge is often irregular, unlike patchy hair loss. There may be redness, scale around the follicles, pustules, or several hairs emerging from the same opening. Patients often report burning, itching or scalp pain beforehand.
Cause: a group of diseases that destroy the stem cells of the hair follicle and replace them with scar tissue, such as lichen planopilaris, frontal fibrosing alopecia (which makes the frontal hairline and eyebrows recede together in postmenopausal women), central centrifugal cicatricial alopecia and folliculitis decalvans.
Severity/urgency: the most urgent of the five, because follicles that have been destroyed do not return no matter how good the treatment. The goal of treatment is to stop progression, not to bring the hair back. Every month of waiting is follicles permanently lost.
When to see a doctor: within the week. Do not wait and see. Diagnosis often needs a scalp biopsy, and the earlier it is done, the more accurate the answer, before scar tissue covers all the evidence.
A practical way to tell by eye: look at the skin in the bald patch under light. If small follicle openings are still scattered across it, it is the non-scarring type, which can recover. But if the skin is smooth and shiny like a scar with no openings at all, treat it as urgent until a doctor proves otherwise.
Hair loss in women by life stage — postpartum, birth control pills, menopause
Hair loss in women often does not have a single cause, but is a temporary condition layered on top of genetic thinning that is already under way. Sorting by life stage helps you guess which will resolve on its own and which needs treatment.
Postpartum (postpartum telogen effluvium): during pregnancy, high estrogen keeps hairs in the growth phase longer than normal. After delivery the hormone level falls and that group of hairs enters the resting phase together. Shedding therefore usually starts 2–4 months after delivery, peaks around months 3–4, then gradually eases, and density returns to nearly the same as before within 6–12 months. This is a normal condition that needs no medication, but iron and thyroid should be checked, because both are often abnormal after childbirth and slow recovery.
Hair loss on birth control pills: it can occur at two points. The first is 1–3 months after starting the pill, especially formulas with a strongly androgenic progestin. The second, which is more common, is 2–3 months after "stopping" the pill, because it is the same kind of hormone change as after childbirth. In both cases it is usually telogen effluvium that resolves on its own within 3–6 months. If the pill must be continued, the doctor may switch to a formula with an anti-androgenic progestin. Do not stop it on your own without consultation, because stopping suddenly may trigger another wave of shedding.
Menopause: falling estrogen makes androgens relatively dominant, so genetic thinning often accelerates at this time. It looks like a part that clearly widens within 1–2 years. Unlike telogen effluvium, the hair does not fall out in clumps but slowly thins. This is the time to start medication, not the time to wait.
Heavy periods and vegetarian diets: these two groups are the clearest risk groups for iron deficiency among Thai women, and it is the easiest cause to correct, so ferritin should always be checked when someone presents with hair loss.
Hair loss in men — where it starts and how fast it progresses
In men, more than 95% of thinning is due to genetics and hormones. The course is fairly predictable. It starts with the temple hairline receding deeply into an M shape, followed by thinning at the crown, and the two areas gradually meet. The hair at the back and above the ears usually remains because the follicles there are not sensitive to DHT, which is the same reason this area is used as the donor source in hair transplants.
The rate of progression varies widely. Some men have a receding hairline that then stops for decades, while others thin noticeably within 3–5 years. The best predictors are family history on both the father's and the mother's side, and the age at onset. The younger the start, especially before 25, the more likely it is to progress.
One caution: a man with heavy shedding all over the scalp with no clear pattern should not be assumed to have genetic hair loss. Hidden conditions should be looked for, such as thyroid disease, iron deficiency and secondary syphilis, which causes scattered small patches of hair loss that look moth-eaten and is often accompanied by a secondary syphilis rash on the palms and soles.
Hair loss from medical conditions and medications
Hair loss can be a sign of many internal diseases, so a physical examination and blood tests are not unnecessary steps. The most common groups in practice are
Iron deficiency: most common in women of reproductive age. The test used is ferritin, not hemoglobin, because iron stores can be depleted before anemia appears. Most studies find an association with hair loss when ferritin is below 30 nanograms per milliliter.
Thyroid disease: both overactive and underactive thyroid can cause hair loss. In hypothyroidism the hair is often dry and coarse, and the outer part of the eyebrows is thin. TSH is the first test.
Autoimmune diseases such as SLE: brittle, short broken hairs along the frontal hairline, together with a cheek rash, joint pain or sun sensitivity.
Secondary syphilis: causes small, irregularly scattered patches of hair loss. Tested with VDRL and TPHA.
Medications that can cause hair loss: chemotherapy (which makes hair fall while it is in the growth phase, so shedding is heavier and faster than other types), anticonvulsants, anticoagulants, oral retinoids for acne, some blood pressure medications, thyroid medications and lithium. The mechanism in most cases is triggering telogen effluvium, so hair usually recovers 3–6 months after stopping the drug. Never stop your regular medication on your own without consulting the prescribing doctor.
Which vitamin deficiency causes hair loss? The answer the evidence supports
"Which vitamin deficiency causes hair loss" is one of the most searched questions, but the answer that matches the evidence is much narrower than advertisements suggest. The principle is that supplementation helps only when there is a true deficiency. Supplementing in someone who is not deficient does not make hair grow, and taking too much of some nutrients can actually cause hair loss.
Iron: the strongest evidence. Check it, and supplement when ferritin is low, taking it with vitamin C and avoiding milk, tea, coffee and calcium at the same time, which reduce absorption. It must be taken continuously for several months until the stores are full.
Vitamin D: an association with patchy hair loss and thinning in women has been reported, but the evidence that supplementation helps hair grow is not clear. Supplement when the level is truly low.
Zinc: clearly relevant only in people who are truly deficient, such as patients after gastric reduction surgery or with intestinal malabsorption.
Biotin: biotin deficiency is very rare in the general population. There is no evidence that supplementing in people who are not deficient helps. There is also a precaution few people know: high-dose biotin interferes with many blood tests, including thyroid levels and cardiac enzymes, giving inaccurate results that can lead to misdiagnosis. Stop it at least 2–3 days before a blood draw and always tell your doctor.
Protein: rapid weight loss or eating less protein than the body needs is a common and straightforward-to-correct cause of telogen effluvium.
Too much of something can cause hair loss: high-dose vitamin A and excess selenium, which is a reason not to take several supplements together on your own without testing.
What a dermatologist will check at the visit
Evaluating hair loss does not take long and is mostly painless. The sequence actually used is
History — duration, pattern of shedding, events in the previous 3–6 months, medications, family history, periods, weight and diet.
Scalp examination with a magnifying device (trichoscopy) — looking at uneven hair thickness that points to genetic thinning, checking whether follicle openings are still present or gone (which identifies the scarring type), and looking at the typical features of patchy hair loss.
Hair pull test — shows whether there is active shedding.
Blood tests as indicated — commonly CBC, ferritin and TSH. VDRL, ANA, vitamin D and sex hormones are ordered when the history points that way.
Scalp biopsy — done when a scarring type is suspected or when the diagnosis is unclear. Local anesthetic is used and the wound is small, about 4 millimeters.
Comparison photographs — more important than people think, because judging whether a medication works requires photos from the same angle and lighting at least 6 months apart. The feeling of "better or worse" is unreliable in the short term.
Topical minoxidil: how to use it effectively
Topical minoxidil is the first-line medication for genetic thinning and can be used by both men and women. It works by widening the blood vessels at the follicle and lengthening the growth phase, so that miniaturized hairs can become thicker again.
Strengths and forms: available as a solution and as a foam, at 2% and 5%.
Dose: men use 5% foam once a day, or 5% solution 1 milliliter twice a day. Women usually use 5% foam once a day, or 2% solution 1 milliliter twice a day.
How to apply: apply to a completely dry scalp, not onto the hair. Part the hair and cover the whole thinning area, spread with fingertips and wash your hands. Leave it for at least 4 hours before getting it wet. If applying before bed, allow time for it to dry so it does not get on the pillowcase.
Time before judging results: assess at 4–6 months, with full results at about 12 months. Quitting at month 2 because it seems not to work is the most common cause of treatment failure.
Increased shedding when starting (shedding phase): in the first 2–8 weeks, many people shed more than before, because the medication speeds up the loss of resting hairs to make way for new ones. This is a sign the drug is starting to work, not a sign of allergy. It settles on its own within 4–8 weeks, and the medication should not be stopped because of it.
What shows it is working or not: at 6 months, if comparison photos show more hairs, or at least that thinning has stopped, it is working and should be continued. If it looks no different at all, a doctor should review whether the diagnosis is correct and consider adding other medication.
Must be used continuously: the medication controls the condition and does not cure it. If you stop, the hair you gained will gradually be lost within 3–6 months.
Side effects seen: dry, itchy, flaky scalp, which usually comes from the propylene glycol in the solution. Switching to the foam usually solves this. In women, facial hair growth may occur if the medication runs down onto the face, so apply only the specified amount and wash your hands every time.
Oral form: low-dose oral minoxidil is used in some cases, but this is off-label use, must be under a doctor's care with monitoring for cardiovascular side effects, and should not be bought and used on your own.
If you have used minoxidil correctly for a full 12 months without results, read about the next steps in Hair Loss Not Improving Even With Minoxidil
Oral finasteride and dutasteride
These medications inhibit the enzyme 5-alpha reductase, so they reduce production of DHT, the direct cause of genetic thinning. They are prescription-only medications.
Finasteride: the dose for male thinning is 1 milligram a day, taken before or after meals. It lowers blood DHT by about 60–70%. Assess the result at 6 months, with the full effect at 12 months. It can be used together with topical minoxidil and usually works better than either alone.
Side effects to know in advance: sexual side effects, such as reduced libido and reduced erections, occur in about 1–2% and mostly return to normal after stopping. Depression and mood changes have been reported in some people. If they occur, tell your doctor so the use of the drug can be reviewed.
Precaution regarding prostate cancer screening: this drug lowers PSA by about half. Always tell your doctor before a PSA test so that the result is interpreted correctly.
Important contraindication: must not be used by women who are pregnant or who may become pregnant, because it harms the development of the genitals of a male baby, and pregnant women should not touch crushed or broken tablets.
Dutasteride: 0.5 milligram a day, inhibits both type 1 and type 2 enzymes and so lowers DHT more. It is used for genetic thinning as off-label use in many countries, and is usually considered when finasteride has not worked well enough. The decision is the doctor's and the dose should not be adjusted on your own.
Must also be used continuously: after stopping, the hair goes back to thinning as before within 6–12 months.
Spironolactone, an option for women
In women with genetic thinning for whom minoxidil alone is not enough, the doctor may consider an anti-androgen medication.
Dose: generally 50–200 milligrams a day, usually starting low and increasing according to response and side effects. This is off-label use.
Time before judging results: 6–12 months, as with other medications in this group.
What must be monitored: blood potassium and blood pressure, because the drug also acts as a diuretic. Irregular periods and breast tenderness may occur.
Contraindications: must not be used in pregnancy. Women planning a pregnancy should use reliable contraception while on the drug, and it must not be used by people with high potassium or impaired kidney function.
Other options in women: birth control pills with an anti-androgenic progestin may help in some cases, considered individually together with contraception needs and the risk of blood clots.
Medications for patchy hair loss: steroids and JAK inhibitors
Patchy hair loss uses a completely different class of medication from genetic thinning, because the cause is immune, not hormonal.
Intralesional steroid injection: triamcinolone acetonide at roughly 2.5–10 milligrams per milliliter, injected into the dermis within the patch every 4–6 weeks. It is the first-line treatment for cases with only a few patches. A side effect seen is temporary skin dimpling at the injection site.
Topical steroids: high-potency ones are used in adults, and they are the first choice in children who cannot yet tolerate injections. Use only for the period the doctor specifies, because prolonged continuous application thins the skin.
Topical immunotherapy and oral immunosuppressants: used in extensive cases or those resistant to initial treatment. They must be under the care of a specialist doctor.
JAK inhibitors: such as baricitinib and ritlecitinib, oral medications approved for severe alopecia areata in adults since 2022. They must be used continuously with periodic blood monitoring, including infection screening before starting. For details, read the article Baricitinib (JAK Inhibitor) for Alopecia Areata
Important precaution: do not apply a topical steroid to a bald patch that has not been diagnosed. If it is actually scalp ringworm, the steroid suppresses inflammation so it looks better for a while, but the fungus spreads further and can become a swollen, inflamed patch that leaves permanent scarring.
Adjunct treatments: PRP, low-level light and hair transplantation
This group is adjunctive options, not substitutes for the main medications, and the levels of evidence differ.
Platelet-rich plasma (PRP) injections: the patient's own blood is spun to separate platelets, which are then injected back into the scalp. It is usually done in rounds about 1 month apart at first and then spaced out. There is fair evidence supporting it in genetic thinning, but the preparation method and number of sessions are not yet standardized, so results differ from person to person.
Low-level light therapy: studies suggest it may slightly increase density in genetic thinning. It must be used regularly for months and is considered an adjunct, not a primary treatment.
Hair transplantation: moving follicles from the back of the head, which are not sensitive to DHT, to the thinning area. It suits people whose condition has stabilized and who have enough donor area. A common misunderstanding is that a transplant does not stop the disease process in the existing hair, so medication must still be continued after the transplant, otherwise the original hair around it will thin until the difference shows within a few years.
What still lacks sufficient evidence: scalp massage with various oils, herbal serums advertised as growing hair, and treatments that claim results within a few weeks.
Every procedure above carries risks and results that differ from person to person. They should be assessed and performed by a doctor, and you should know all the options, including their limitations, before deciding.
Anti-hair-loss shampoos and supplements: how much do they really help?
Shampoo stays on the scalp for only a few minutes before being rinsed off, so it cannot be the main treatment for hair loss. But it is not entirely useless either. Its real role is managing scalp conditions that make shedding worse.
Ketoconazole 2% shampoo: there is evidence that it helps as an adjunct in genetic thinning, and it directly treats seborrheic dermatitis, which causes itching and increased shedding. Use it twice a week, leaving it on the scalp for 3–5 minutes before rinsing. Rinsing immediately will not work.
Other anti-dandruff shampoos, such as zinc pyrithione and selenium sulfide: help control dandruff and itching, which reduces the scratching that causes hair to break and fall. If dandruff is also present, see how to tell the causes apart and treat it at What Causes Dandruff.
Shampoos advertised as growing hair or reducing hair loss: most lack clinical data at the same level as medications. They are fine as gentle shampoos but should not replace treatment.
Hair supplements: the same principle applies: they help only when there is a true deficiency. Taking many at once increases the chance of excess vitamin A or selenium, which itself causes hair loss. If you want to supplement, test first for what you are lacking.
Washing your hair often does not make you lose more hair. The hair that falls out during washing was already ready to fall. Skipping washes for several days only makes it fall out all at once, which looks more alarming than before.
Signs that mean seeing a dermatologist without waiting
The skin in the bald patch is smooth and shiny with no visible follicle openings, or has scale, redness, pustules or burning pain — scarring hair loss needs to be identified as quickly as possible.
Hair loss that progresses quickly within a few weeks, or so much that the scalp clearly shows in under 3 months.
Hair loss in a child with scale, a red scalp or enlarged lymph nodes behind the ears — think of scalp ringworm, which needs an oral antifungal; a topical alone will not cure it.
Hair loss together with physical symptoms, such as marked weight change, abnormal periods, fatigue, palpitations, joint pain, or a rash on the palms and soles.
Patchy hair loss together with loss of eyebrows, beard or eyelashes.
Correct, continuous use of minoxidil for a full 6 months with nothing changing.
Chronic scalp itching together with hair loss. See how to tell the causes apart at What Causes an Itchy Scalp
In brief
Shedding 50–100 hairs a day is normal. What deserves attention is shedding of more than 100 hairs for more than 2 weeks in a row, or a part that is wider than in old photos.
First tell apart shedding (many hairs fall out but thickness is unchanged, usually resolves in 3–6 months) from thinning (hairs get progressively finer, does not resolve on its own, needs medication).
Telogen effluvium is preceded by a trigger about 2–3 months earlier. Fix the cause and it recovers on its own. Genetic thinning responds better the earlier medication is started.
The main medications with evidence are topical minoxidil 2–5% for all sexes, finasteride 1 milligram a day in men, and spironolactone in some women. All must be used continuously and judged at 6–12 months.
Increased shedding in weeks 2–8 after starting minoxidil is normal and is not a reason to stop.
Supplements help only when there is a true deficiency. Test first, especially iron and thyroid.
What to do if you are still unsure after reading: take photos of the center part and hairline in the same lighting as a starting record, then book a dermatologist to identify the type before buying any medication or supplement.
See all other skin condition articles at All Skin Condition Articles
Frequently asked questions
What causes hair loss, and how do I fix it?
Hair loss comes from five main groups: telogen effluvium after illness or stress, genetic and hormonal thinning, immune-driven patchy hair loss, traction hair loss, and scarring hair loss. Fixing it therefore starts with working out which type it is, because the medications are completely different. For telogen effluvium, fix the cause, such as replacing iron when it is low and bringing thyroid to normal, and the hair will come back on its own within 6–12 months. For genetic thinning, you need to start topical minoxidil, and in men finasteride 1 milligram a day may be added. What you should not do is buy hair vitamins to take on your own before knowing which type it is, because it wastes both time and the chance for medication to work.
What should I use for hair loss, and which medication really works?
There are only a few medications with clear medical evidence. The first is topical minoxidil, 5% for men and 2–5% for women, applied to a dry scalp and left for at least 4 hours, used continuously and judged at 4–6 months. The second is oral finasteride 1 milligram a day, used in men and prescribed by a doctor. The third is spironolactone, used in some women with monitoring of potassium. Patchy hair loss uses a different class: intralesional steroid injections or JAK inhibitors. Shampoos and supplements are only adjuncts, not the main treatment, and choosing a medication must go through diagnosis and prescription by a doctor.
Is treatment for hair loss in women different from men?
It differs in the details. Topical minoxidil can be used by both sexes, but women usually use 5% foam once a day or 2% solution twice a day to reduce the chance of facial hair growth. Finasteride is a medication used in men and must never be used by women who are pregnant or may become pregnant. The option for women who do not respond enough is spironolactone 50–200 milligrams a day, which needs monitoring of potassium and blood pressure and contraception during use. Another difference is that women need a more thorough search for hidden conditions, especially ferritin and thyroid, because iron deficiency is much more common and is the easiest cause to correct.
Is losing 100 hairs a day normal?
Yes. Most people lose 50–100 hairs a day as part of the natural hair cycle. What marks it as abnormal is not a single day's number but shedding of more than 100 hairs a day continuously for more than 2 weeks. The reliable way to measure is to collect all the hair shed over 7 days in a row and work out the average, because on a wash day shedding is 2–3 times higher than usual without being abnormal. Something more important than counting hairs is looking at density. If shedding is heavy but the part is unchanged, it is usually temporary, but if shedding is not heavy yet the part keeps widening, that is thinning, which needs a doctor to start medication.
I lost hair on birth control pills. Will it go away if I stop?
Mostly yes, but you need to understand the timing first. Pill-related hair loss can occur at two points. The first is 1–3 months after starting, especially with formulas that have a strongly androgenic progestin. The second, which is more common, is 2–3 months after stopping the pill, because the hormones change in the same way as after childbirth. In both cases it is telogen effluvium that stops on its own within 3–6 months, with density returning within 6–12 months. One precaution: do not suddenly stop the pill on your own, because it may trigger another wave of shedding. If you must continue, consult a doctor about switching to a formula with an anti-androgenic progestin, and if shedding lasts longer than 6 months, look for other causes such as low iron or thyroid disease.
Heavy hair loss: what conditions could it be?
The most common is telogen effluvium from high fever, surgery, childbirth, rapid weight loss or stress, which is preceded by a trigger about 2–3 months earlier. Next is genetic and hormonal thinning. The internal diseases that cause hair loss and must always be checked are iron deficiency, seen from ferritin; thyroid disease, both overactive and underactive, seen from TSH; autoimmune disease such as SLE; and secondary syphilis, which causes small, irregularly scattered patches of hair loss. Many medications can also cause hair loss, such as chemotherapy, anticonvulsants, anticoagulants and oral retinoids. If hair loss comes with other physical symptoms, such as fatigue, weight change or abnormal periods, see a doctor for blood tests to look for the cause.
The information in this article is for education and is not a diagnosis or a prescription for any individual. The choice of medication, dose and duration of use always requires an examination and prescription by a doctor.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed September 20, 2026
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