What is alopecia? Causes, types and treatment

Published on
19/8/26
Last update
19/8/2026
The summary

Alopecia comes in various forms and has different causes. Find out how to recognise them and why an accurate diagnosis is important for treatment.

Short answer: Alopecia is the medical term for hair loss and encompasses several forms, each with a different cause. In men, androgenetic alopecia is the most common; it is hereditary and hormone-related. Other forms, such as alopecia areata, require a completely different treatment.

You may notice your hair is becoming thinner, or perhaps you suddenly see a bald patch appearing. ‘Alopecia’ is often the first term you come across, but it by no means covers just one condition. The most common form in men progresses gradually and is hereditary; other forms develop suddenly or have a completely different cause, such as an overactive immune system. This article explains exactly what alopecia is, what types exist, how to distinguish between them, and which treatment is appropriate for each form.

What exactly is alopecia?

Alopecia means hair loss or baldness and is an umbrella term, not a diagnosis in itself. This term covers several conditions, each with its own cause and its own approach. Androgenetic alopecia is by far the most common form in men: hereditary, hormonally determined hair loss that progresses gradually. Alopecia areata is an autoimmune reaction in which the immune system attacks the body’s own hair follicles, resulting in patchy bald spots.

Scarring alopecia, also known as cicatricial alopecia, occurs when the hair follicles themselves are permanently damaged, for example due to inflammation, trauma or a skin condition, causing hair growth in that area to cease permanently. In addition, there are less commonly discussed forms such as telogen effluvium, a temporary form of hair loss that can occur following stress, illness or a traumatic event. The crucial point is that the cause determines what works: a treatment that is effective for one form may have no effect at all on another.

Androgenetic alopecia: the most common form in men

Androgenetic alopecia occurs because dihydrotestosterone (DHT) causes sensitive hair follicles to gradually miniaturise. This happens via the enzyme 5-alpha-reductase, which converts testosterone into DHT, and primarily affects men with a genetic predisposition to this condition. Research into the mechanism of male pattern hair loss shows that this miniaturisation follows a fixed, predictable pattern, categorised using the Norwood scale from stage 1 to 7. Hair loss usually begins at the hairline, with characteristic receding temples, and at the crown. This form is progressive but highly treatable, particularly in the early stages 1 to 4. This is precisely the form that Fellos’ treatment for androgenetic alopecia targets, using finasteride, dutasteride and minoxidil.

Alopecia areata: a different condition requiring a different approach

Alopecia areata is an autoimmune disease and, unlike androgenetic alopecia, is not related to DHT or heredity. In this condition, the immune system attacks healthy hair follicles, causing sudden, round, sharply defined bald patches to appear, usually on the scalp but sometimes also in the beard or eyebrows. A recent review shows that alopecia areata affects around 2 per cent of people at some point in their lives and can occur at any age, including in young men. Its course is unpredictable: the condition may resolve spontaneously, but it may also recur.

It is important to be clear about this: finasteride, dutasteride and minoxidil are not intended for alopecia areata and have not been studied or authorised for this condition. These treatments act on DHT or blood flow, not on the autoimmune process that attacks the hair follicles in alopecia areata. Treatment for alopecia areata, for example with corticosteroids or immunotherapy, is not part of what Fellos offers. If you suspect this condition – characterised by sudden, round bald patches – your GP or dermatologist is the right person to consult.

Recognising symptoms: how do you know which form you have?

The way in which hair loss develops often reveals which form is involved. Androgenetic alopecia progresses gradually, starts at the hairline or crown, always leaves a ring of hair intact at the back of the head, and is not accompanied by itching or inflammation. Alopecia areata, on the other hand, develops suddenly, with round or oval bald patches and a sharp edge, sometimes preceded by itching or a tingling sensation, and can also affect the nails, causing small pits. In scarring alopecia, the skin in the bald patch often looks different: shiny, red or inflamed, and hair growth does not return in that area. Are you unsure which type applies? A doctor can often diagnose this quickly with a physical examination.

When should you see a doctor?

Always see your GP or a dermatologist if you experience sudden or patchy hair loss, itching, pain or redness of the scalp, or hair loss in unusual areas such as the eyebrows, beard or body hair. Rapidly worsening baldness or uncertainty about the cause is also a reason to make an appointment. According to Thuisarts.nl, a medical assessment is always the safest first step when in doubt, particularly as treatment varies completely depending on the type. An incorrect assessment will cost you time and, in some cases, may also result in the loss of hair follicles that cannot be restored.

How does Fellos help with androgenetic alopecia?

Fellos focuses exclusively on androgenetic alopecia and not on other forms of hair loss. Following an online consultation, a Dutch doctor will assess your situation and confirm whether it is indeed androgenetic alopecia. Based on this, a personalised treatment plan is drawn up, usually involving finasteride and/or minoxidil, and, if these prove insufficient, possibly dutasteride off-label. Research into the effectiveness of these treatment options shows that results are usually visible after 3 to 6 months, with maximum results achieved after approximately 24 months with consistent use. Fellos’ treatment is expressly not suitable for, nor intended to treat, alopecia areata or scarring alopecia.

The correct diagnosis is the first step

Alopecia is not a single, straightforward condition: the type determines what works. In the case of hereditary hair loss, or androgenetic alopecia, Fellos can intervene in good time with proven medication and medical guidance, ideally as early as the early Norwood stages. For other forms of hair loss, such as alopecia areata or scarring alopecia, an accurate diagnosis by a doctor is the first and most important step before considering any treatment.

Sources

Fellos adheres to strict editorial guidelines for sources to ensure the accuracy and timeliness of our content. Our content is based on scientific publications, research from academic institutions, and reputable medical organisations. If you notice an error, please let us know at care@fellos.nl.
 

This article is intended for informational purposes only and does not constitute medical advice. The information herein is not a substitute for professional medical advice and should never be relied upon. Always discuss the risks and benefits of any treatment with your doctor.

This content was last updated on

19/8/2026

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