Hair Loss: Normal Shedding or Alopecia? Treatments That Work
Every day you lose between 50 and 100 of the roughly 100,000 hairs on your head, and that doesn't mean you're going bald. Here we explain how to tell normal shedding from alopecia, which treatments work and which products are just marketing.
The hair cycle: why losing hair every day is normal
A hair grows one centimetre a month for a period of two to six years. It then rests for two or three months before falling out.
That's why losing a hundred hairs a day isn't baldness: it's turnover. Each follicle follows its own rhythm. If they all shed at the same time, you would lose all your hair at once.
Telogen effluvium: hair loss triggered by something that happened months ago
The most alarming kind of hair loss doesn't start on the day you notice it. Telogen effluvium is a response to a shock to the body two or three months earlier: a high fever, childbirth, surgery, severe stress or a very low-calorie diet.
In response to that shock, the follicle abruptly stops growing and many hairs enter the resting phase at the same time. When new hairs start to grow, they push the old ones out and the shedding begins.
Telogen effluvium isn't treated with shampoo. It resolves within six to twelve months once the cause is corrected.
Androgenetic alopecia: the most common cause of baldness
Androgenetic alopecia is a different process and the most common cause of baldness. In men, it affects the temples and the crown. In women, it causes diffuse thinning along the centre parting.
The culprit is dihydrotestosterone, which shortens the hair cycles and miniaturises the follicle.
Three evidence-backed treatments
Minoxidil. It is applied to a dry scalp twice a day and prolongs the hair's growth phase. Results should be assessed from the fourth month onwards, not before.
Finasteride or dutasteride. These are taken orally and reduce the dihydrotestosterone that shortens the hair cycles. They are prescribed only to men and always under medical supervision.
Spironolactone in women. It blocks the androgens that miniaturise the follicle. It requires a prescription, and blood pressure and potassium levels must be monitored. It should not be taken during pregnancy.
By contrast, anti-hair-loss shampoos and biotin, when there is no deficiency, do not reverse this process.
Other medical causes and common myths
Other causes of hair loss require assessment by a dermatologist: low ferritin, hypothyroidism or hyperthyroidism, and alopecia areata. The latter is autoimmune in origin, causes round patches and sometimes affects the nails as well.
Cutting your hair doesn't make it stronger, because the root receives no signals from the ends. Washing it every day doesn't cause baldness, since the follicle sits beneath the skin. Nor does a fright turn your hair grey: hair colour depends on melanocytes, and their loss is due to genetics or age.
When to see a dermatologist
It's worth seeing a doctor if you lose more than a hundred hairs a day for more than a month. The same applies if you notice smooth patches, itching, flaking or scarring, or if you experience fatigue, weight changes or irregular periods.
A dermatologist may order a ferritin and thyroid hormone test, as well as examine your scalp with a dermatoscope. The hair you lose today reflects what happened three months ago. If you do have alopecia, an early diagnosis really does change the outcome.
Frequently asked questions
How many hairs is it normal to lose a day?
It's normal to lose between 50 and 100 hairs a day. This is part of the hair's natural turnover and is not a sign of baldness.
Do anti-hair-loss shampoos work?
No. Anti-hair-loss shampoos do not reverse androgenetic alopecia or treat telogen effluvium.
How long does it take for minoxidil to work?
Results should be assessed from the fourth month of use onwards, not before.
Does washing your hair every day cause baldness?
No. The follicle sits beneath the skin, so washing your hair daily does not cause baldness.
Informative article written with the help of AI tools from the verified script of the video. The video is in Spanish.