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Hair loss
Hair loss is one of the most common reasons for a dermatologist visit, and one of the topics with the most inaccurate information circulating around it. This text explains what is normal, what the most common causes are in women and men, and when it is time to see a doctor.
How many hairs a day is normal
There are roughly one hundred thousand hairs on the head. Each goes through a cycle with three main phases, growth, transition and rest, after which the hair falls out and makes room for a new one.
Because those phases are not synchronised, at any moment part of the hair is in the resting phase. That is why a certain number of hairs is lost every day and it is entirely expected. The range usually quoted is fifty to a hundred a day, with the caveat that counting is unreliable and that wash day always looks more dramatic.
What is really informative is not the number of hairs in the drain but the change: whether density has visibly decreased over the past few months, whether the ponytail has become thinner, whether the parting has widened.
The most common causes in women
Telogen effluvium. Diffuse shedding across the whole head, usually two to three months after an event: childbirth, a more severe infection, surgery, rapid weight loss or major stress. The most common cause of sudden shedding in women.
Iron deficiency. Very common and easy to check. Ask for ferritin, not just iron, because ferritin shows the stores.
Thyroid. Both reduced and increased function can show up in the hair.
Hormonal changes. Pregnancy, the end of breastfeeding, stopping or changing oral contraception, perimenopause.
Hereditary thinning. In women it is most often seen as gradual widening of the parting through the middle of the head, with the front hairline preserved. More in the text Androgenetic alopecia.
Hairstyles that pull. Tight buns, braids and extensions pull on the root for years and can cause shedding along the hairline.
The most common causes in men
Androgenetic alopecia is by far the most common. It starts with the hairline receding and thinning at the crown, develops over years and is hereditary.
Besides that, men experience the same causes as women, iron deficiency, thyroid problems, telogen effluvium after illness or stress, only less frequently.
What does not cause hair loss
A few claims that keep being repeated and do not hold up:
- A hat does not cause hair loss.
- Frequent washing does not cause shedding. The hairs you see while washing were already in the resting phase.
- Cutting affects neither density nor growth rate. The hair is shortened in the middle, the root stays the same.
- Going without shampoo does not help. Not washing only moves the moment when you see the accumulated hairs.
When to see a doctor
Without delay if:
- hair falls out in clumps or in clearly defined round patches
- the scalp is red, painful, itchy or scaling
- eyebrows or eyelashes are being lost as well
- the shedding is accompanied by fatigue, weight change, or changes to the nails or skin
- the condition is getting worse quickly
A dermatology appointment usually includes a conversation about the timeline, an examination of the scalp with a magnifying device and, if needed, laboratory tests. We have given an overview of the types of shedding and their features in the text Alopecia.
What you can do yourself
A few things that do no harm and make sense while you wait for an appointment or while recovery is under way:
- check iron, ferritin and thyroid function if it has not been done recently
- do not start restrictive diets while the shedding is ongoing
- loosen hairstyles that pull
- the scalp is cared for like any other skin: do not dry it out and do not rub it harshly
- photograph the scalp once a month, in the same light; comparison over time is more reliable than impression
About scalp care products
Cosmetic scalp products deal with the care of the skin and the appearance of the hair. They have no role in diagnosis and do not replace treatment when treatment is needed.
If you want to know what such products contain and how labels are read, see the text Hair serums and ampoules.
In short
Losing a certain number of hairs a day is normal. What is not normal is a visible change in density over a few months, shedding in defined patches or changes on the scalp. The first step is not a product but establishing the cause, and the most common causes are checked with simple tests.