You suddenly see it in the mirror, or someone points it out: a round, bald spot on your head, the size of a coin. No itch, no pain, just bare skin where hair used to be. That's a different story than a hairline that slowly recedes or a crown that thins over the years.
Many men lump all hair loss together. Understandable, because the end result sometimes looks similar. But a sudden round bald spot is usually something different from hereditary baldness, and the approach differs significantly.
What is alopecia areata?
Alopecia areata is an autoimmune condition. Your immune system mistakenly identifies hair follicles in a specific area as intruders and attacks them. The hair follicles themselves are not damaged; they are only temporarily deactivated. This stops local hair growth, and the hair falls out within a few weeks.
The characteristic feature is a sharply defined, round or oval spot. The skin underneath looks perfectly healthy; there is no redness or flaking. Sometimes you see short hairs at the edge of the spot that narrow towards the root, somewhat like an exclamation mark. This is a sign that the condition is currently active.
Alopecia areata can occur anywhere hair grows: on the scalp, in the beard, in the eyebrows. In a small percentage of people, it spreads to the entire head (alopecia totalis) or the entire body (alopecia universalis), but this is an exception. For most people, it remains limited to one or a few spots.
What is hereditary baldness?
Androgenetic alopecia, the official name for hereditary baldness, works very differently. Here, the hair follicles are not attacked by your immune system, but gradually become sensitive to DHT, a substance produced from testosterone. Under the influence of DHT, the hair follicles shrink over time, causing the hair they produce to become progressively thinner and shorter until almost nothing is left.
This process takes years, not weeks. It also follows a recognizable pattern: the hairline recedes at the temples, or the crown thins, often in combination. A round hole somewhere on the back of the head, as with alopecia areata, does not fit this pattern.
If you want to know more about this, read our article on DHT and how it causes baldness.
The main differences
A few points to distinguish between the two:
- Shape and location — Alopecia areata shows sharply defined, round or oval patches, often in an unexpected location. Hereditary baldness follows a fixed pattern: hairline and crown.
- Speed — A patch of alopecia areata can become bald in a few weeks. Hereditary baldness develops over years.
- The skin — In alopecia areata, the skin in the bald spot is smooth and healthy. With hereditary baldness, you don't see sudden bald spots, but gradually thinning hair growth.
- Age of onset — Alopecia areata can occur at any age, including in young children. Hereditary baldness usually only begins in the late teens or twenties and gradually worsens.
- Family history — Hereditary baldness is more common if it also occurs in your father, grandfathers, or brothers. Heredity also plays a role in alopecia areata, but it is less predictable, and it often occurs together with other autoimmune conditions such as thyroid problems.
Still in doubt after reviewing this list? Then a general practitioner or dermatologist is the right next step. The difference is often clearly visible to someone who has assessed it many times.
What causes alopecia areata?
The exact cause is not entirely clear, but it involves a disruption of the immune system, often in combination with genetic susceptibility. If alopecia areata runs in your family, you are more likely to get it too.
Stress is often mentioned as a trigger, and some people themselves notice a connection with a stressful period. However, the scientific evidence for this is thin. Most recent research points primarily to genetics and the immune system as driving factors, with stress as a possible but unconfirmed catalyst. So it's not that you've caused it yourself by a busy period at work.
What can you do about alopecia areata?
The good news: in about 80 percent of people with a single small spot, the hair grows back spontaneously within six months, without treatment. The hair follicles are not destroyed, only temporarily shut down.
Nevertheless, it is wise to see a general practitioner as soon as you discover an unexplained bald spot. They can confirm the diagnosis and, if necessary, refer you to a dermatologist. For larger or expanding spots, treatments such as corticosteroids applied topically or via injection are possible.
Since 2025, two JAK inhibitors have also been available in the Netherlands that are reimbursed for more severe cases: baricitinib and ritlecitinib. These are medications that suppress the overactive immune system, and research shows that they lead to noticeable hair growth in a significant number of users. This is relatively new and is only used in serious cases, in consultation with a dermatologist.
A serum or derma roller is not the first step here. These products are designed to support hair follicles sensitive to DHT, not to suppress an autoimmune reaction. With alopecia areata, the problem lies elsewhere, so a different approach is appropriate.
What can you do about hereditary baldness?
With androgenetic alopecia, the approach is different because the cause is different. Here, the aim is to inhibit DHT and support active hair follicles before they miniaturize too much.
A growth serum with ingredients like Redensyl and caffeine can stimulate active hair follicles. A derma roller, if used correctly, can improve the absorption of such a serum. For most men with a genetic predisposition, this is a logical starting point.
Can they occur together?
Yes, they can. Someone with a genetic predisposition to baldness can also develop alopecia areata independently. In that case, you see two patterns simultaneously: a gradually receding hairline and a sudden round patch elsewhere. This sometimes makes it more difficult to assess, and this is precisely the situation in which a dermatologist can most quickly determine the difference.
When to see a general practitioner?
In any case, consult your general practitioner if you see a bald spot that does not fit a gradually receding hairline, if the spot is growing rapidly, if you have multiple spots at once, or if you have other complaints besides hair loss, such as fatigue or changes in your nails. The latter sometimes occurs with alopecia areata and can help with the diagnosis.
In short
A round, sharply defined bald spot is usually alopecia areata, an autoimmune reaction that in many cases resolves spontaneously. Hereditary baldness, on the other hand, develops gradually according to a fixed pattern at the hairline and crown, caused by DHT. The two require a different approach: for alopecia areata, a general practitioner or dermatologist is the first step, while for hereditary baldness, you can already do something yourself with a serum, derma roller, or medication. Knowing which of the two you have prevents you from investing time and money in something that is not the right solution for your situation.
Frequently asked questions
Can you get alopecia areata at any age?
Yes, alopecia areata can occur at any age, from young children to adults in later life, although for many people it starts before their thirtieth birthday.
Is alopecia areata contagious?
No, alopecia areata is not contagious. It is an autoimmune reaction of your own body and has nothing to do with bacteria, viruses, or fungi that can be transmitted to others.
Can you confidently determine the difference with a photo yourself?
No, although the characteristics in this article provide a good initial indication, it remains difficult to achieve complete certainty with just a photo. A doctor can examine the scalp closely and look for details that are less visible in a photo.
Is alopecia areata more common with other autoimmune conditions?
Yes, alopecia areata is more common in people who also have other autoimmune conditions, such as thyroid problems, vitiligo, or type 1 diabetes. This points to a shared underlying susceptibility of the immune system.
Can you use a serum while waiting for a diagnosis?
Yes, you can do so without risk, as a serum with ingredients like Redensyl does not affect the autoimmune process. It does not solve the problem of alopecia areata, but it also causes no harm while awaiting a diagnosis.
Is there a test that confirms alopecia areata with certainty?
A doctor can usually make the diagnosis based on the characteristic appearance of the spot, sometimes supplemented with a trichoscopy. In doubtful cases, a small skin biopsy can provide more certainty, although this is not always necessary.
Can alopecia areata return after recovery?
Yes, alopecia areata can return, even after full recovery from a previous spot. For some people, it remains a single episode, while for others, it returns periodically in the same or other spots.
Are JAK inhibitors also suitable for a single small spot?
In the Netherlands, JAK inhibitors are mainly used for more severe or extensive forms of alopecia areata, not as standard for a single small spot that often heals spontaneously. A dermatologist determines per situation whether this treatment is appropriate.
Can you prevent alopecia areata?
No, there is no known way to prevent alopecia areata, as it is related to a combination of genetic predisposition and an autoimmune reaction that cannot be controlled by lifestyle.
Does smoking or diet affect the risk of alopecia areata?
There is no strong evidence that smoking or specific diet directly affects the risk of alopecia areata. The condition is mainly explained by genetic and immunological factors, not by lifestyle choices.
