Hair Loss: Causes, Tests and What to Do

How much hair loss is normal

A person loses 50–100 hairs every day. This is a natural cycle: a hair grows, then enters a resting phase and falls out, and a new one grows in its place.

Signs that deserve a closer look:

• you are losing noticeably more hair than before;
• there is much more hair on your pillow, clothes and in the shower drain;
• your hairstyle has lost volume and your parting has become wider;
• this has been going on for more than 2–3 months.

The hair growth cycle

Every hair goes through three phases:

• Anagen — active growth, lasts 2–6 years. Most hair, about 85–90%, is in this phase.
• Catagen — a transitional phase lasting a few weeks.
• Telogen — a resting phase of about 3 months. At the end of it, the hair falls out.

Severe stress, illness or a deficiency can “switch” part of your hair from growth to rest all at once. That is why shedding does not appear immediately but 2–3 months after the event, and why the cause is so hard to trace on your own.

How to assess the situation at home

These methods do not replace a diagnosis, but they help you understand whether there is reason for concern.

• Pull test. Take a strand of about 60 hairs and gently slide your fingers from the root to the tips. If more than 5–6 hairs come away, it is worth paying attention.
• Counting. For several days, count the hairs on your brush and in the drain after washing. Well over 100 a day is a reason to monitor the trend.
• Parting photos. Once a month, photograph your parting and crown under the same lighting. This makes it easier to notice a widening parting or thinning.
• Condition of the hair. If the fallen hairs have a small white bulb at the end, that is the normal cycle. If hair breaks in the middle of the strand, the cause is more often hair care.

Causes of hair loss

Telogen effluvium: a reaction to stress

The most common type. Severe stress, illness with a high temperature, surgery, childbirth or rapid weight loss push part of your hair into the resting phase. This is usually temporary, and hair gradually recovers within 6–12 months.

Illness, viral infections and rapid weight loss

Hair loss after flu, respiratory infections, COVID-19, surgery or a strict diet is very common. The body spends its resources on recovery, and hair temporarily takes a back seat. 2–3 months after an illness, or a diet low in calories and protein, hair may shed more noticeably.

Nutrient deficiencies

Hair is sensitive to a lack of iron, vitamin D, vitamin B12, zinc and protein. The risk is higher with strict diets, vegetarian and vegan eating, heavy periods and digestive problems.

Thyroid problems

Both an underactive and an overactive thyroid can cause diffuse thinning of the hair, often together with changes in weight, fatigue and dry skin.

Hormones

Changes after childbirth, during menopause, with polycystic ovary syndrome, and starting or stopping hormonal contraceptives can all affect the hair.

Androgenetic alopecia

A hereditary cause, most common in men and not rare in women. Vitamins do not solve the problem here, and a consultation with a trichologist is needed.

Alopecia areata and scalp conditions

Patchy hair loss (round bald spots), heavy flaking, itching or redness require a diagnosis from a dermatologist.

Hair care and external factors

Tight hairstyles, frequent dyeing and bleaching, hot styling and extensions can cause breakage and even shedding.

Medications

Some medications can affect the hair. If shedding began after you started a new medicine, discuss it with your doctor and do not stop it on your own.

Hair loss in women

In women, hair loss is most often linked to several factors at once:

• iron deficiency due to heavy periods, diets or vegetarian eating;
• hormonal changes: childbirth, menopause, PCOS, starting or stopping hormonal contraceptives;
• thyroid problems;
• stress and chronic lack of sleep.

The typical picture is diffuse thinning across the whole head and a widening parting without receding hairline. If hair loss comes with irregular periods, acne or excess body hair, it is worth seeing a gynecologist-endocrinologist.

Hair loss after childbirth

During pregnancy, hair enters the resting phase less often, so it looks thicker. After birth, hormone levels change and the accumulated “extra” hair falls out all at once. The peak usually comes 3–4 months after delivery.

• This is common and usually temporary; hair recovers within 6–12 months.
• Lack of sleep, stress and iron deficiency after childbirth and breastfeeding add to the effect.
• If shedding is heavy or drags on, check ferritin, hemoglobin and TSH.
• While breastfeeding, discuss any supplements with your doctor.

Hair loss in men

In men, the most common cause is androgenetic alopecia: a receding hairline and thinning at the crown. It is hereditary and develops gradually.

• Vitamins have practically no effect on this type of hair loss.
• Iron deficiency is rare in men, so iron supplements without tests are not recommended.
• The earlier you see a trichologist, the more options there are to slow the process.
• If hair falls out suddenly or in patches, the cause may be different — stress, illness or a thyroid disorder — so an examination is needed.

Which tests to take for hair loss

There is no need to guess the cause. A basic checkup helps identify the most common deficiencies and disorders.

Depending on the indications, your doctor may add zinc, folate, free T4, anti-TPO antibodies, a hormone panel and trichoscopy.

Preparation

• give blood in the morning on an empty stomach — 8–12 hours without food, water is allowed;
• do not take iron for 24–48 hours before the test unless your doctor says otherwise;
• high doses of biotin can distort hormone test results: pause it for a few days and tell your doctor;
• avoid intense workouts and alcohol for 24 hours beforehand;
• do all tests in the same laboratory so that results can be compared over time.

How to understand your test results

Use the range printed on your laboratory’s report. The figures below are general and only give an idea of the order of magnitude.

Important points

• “Within range” does not always mean “optimal for hair”. The lower limit for ferritin in laboratories is often about 10–15 ng/mL, while many doctors aim for higher values (from 30 ng/mL) in cases of hair loss, so a result “within the normal range” is worth discussing with your doctor.
• Borderline values — B12 200–300, TSH near the upper limit, vitamin D 20–30 — are best assessed together with symptoms and repeat tests.
• A single test does not make a diagnosis: the result is affected by inflammation, supplement intake and the time of sampling.
• Do not choose your own doses based on the numbers. Iron, zinc and vitamin D are harmful in excess.

What can help with hair loss

Deficiency. It is corrected based on test results. Iron, vitamin D, B12 and zinc are chosen according to blood levels and need, not “just in case”.

Stress or illness. Often, time, restored sleep and full nutrition with enough protein are sufficient. Supplements can support your diet but do not replace removing the cause.

Androgenetic alopecia. Methods are chosen by a trichologist. Depending on the situation, a doctor may offer medications, for example minoxidil, or procedures, for example PRP therapy. The choice, dosage and regimen are determined only by a doctor. Vitamins and hair care are only supportive here.

Thyroid or hormonal problems. Treatment by the appropriate specialist is needed, and once the condition normalizes, hair usually recovers gradually.

Vitamins and supplements: realistic expectations

Vitamins and minerals take part in maintaining the normal condition of hair, and when a deficiency is confirmed, replenishing them makes sense. If there is no deficiency, do not expect a miracle effect.

When choosing a complex, look at the composition and dosage, avoid duplicating ingredients, be careful with vitamin A in excessive doses — it can actually increase hair loss — and do not combine several complexes without need.

Read more in the article “Vitamins for hair: which ones really work and how to choose them”.

Caring for your scalp and hair

• Wash your hair regularly with a shampoo suited to your skin type.
• Limit hot styling, frequent dyeing and tight hairstyles.
• Comb gently, especially wet hair.

Nutrition for healthy hair

Hair consists mainly of the protein keratin, so your diet matters. Too few calories and too little protein are one of the common hidden causes of hair loss.

• Protein: meat, fish, eggs, dairy, legumes, tofu.
• Iron: red meat, liver, legumes, buckwheat. Plant iron is absorbed better together with sources of vitamin C — peppers, citrus fruit, berries.
• Zinc: seafood, meat, pumpkin seeds, nuts, legumes.
• B12: meat, fish, eggs, dairy. Vegans and vegetarians need to monitor their levels separately.
• Omega-3: fatty fish, flaxseed oil, walnuts.
• Vitamin D: fatty fish, egg yolks, sunlight, but in winter diet alone is usually not enough.

Myths about hair loss

• “Washing your hair often causes hair loss.” No. Washing simply removes hair that has already fallen out.
• “Hats cause baldness.” No, unless they are tight or irritate the skin.
• “Biotin helps everyone.” Without a deficiency there is no evidence of benefit from high doses, and it affects test results.
• “A shampoo or mask will stop hair loss.” Hair care improves the look of hair but does not remove the cause.
• “The more vitamins, the better.” An excess of iron, zinc or vitamin A can do harm.

When to see a doctor right away

Do not put off a visit if:

• hair comes out in clumps or bald patches appear;
• hair loss comes with fatigue, sharp changes in weight, irregular periods or swelling;
• your scalp hurts, flakes, itches or is inflamed;
• hair loss began suddenly and is progressing quickly;
• there is no improvement 2–3 months after the cause has been removed.

How long to wait for results

Hair grows about 1 cm a month. Even after the cause is removed, a reduction in shedding is usually noticeable after 2–3 months, and regaining density can take 6 months or longer.

Frequently asked questions