Hair loss: an overview of different causes

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An orientation guide to different causes and patterns of hair loss

Hair loss is often described as a single problem, but from a clinical perspective it is better understood as a symptom with multiple underlying causes.

Different biological mechanisms can affect the hair growth cycle or the hair follicle itself, resulting in distinct patterns, timelines and progression.

Because these mechanisms differ, identifying which type of hair loss may apply is an essential first step before considering next steps or support.

Identify your type of hair loss

Start the Hair Check (2 minutes)

One symptom, different biological mechanisms

In clinical practice, hair loss is classified based on how the hair follicle is affected and what triggers the change. Some patterns are reactive and potentially temporary, while others are driven by genetic sensitivity or immune dysregulation and may follow a longer-term course.

The goal of this page is not to diagnose, but to help you recognise the most common categories and navigate to the right in-depth resource.

The 3 most common hair loss categories

  • Alopecia androgenetica (hereditary thinning)

    Alopecia androgenetica is the most common form of long-term hair loss. It involves gradual miniaturisation of hair follicles, producing finer hairs over time and reduced density in characteristic areas.

    In men, thinning often becomes noticeable at the temples and crown. In women, it more commonly presents as widening of the part line or reduced density across the top of the scalp.

    Read the full guide 

  • Telogen effluvium (diffuse shedding)

    Telogen effluvium is characterised by increased, diffuse shedding across the scalp. Rather than a receding hairline or distinct bald patches, people typically notice more hair in the shower, on the pillow or when brushing.

    This pattern is often associated with internal stressors such as illness, hormonal changes, emotional stress, surgery, nutritional strain or recovery after a significant event.

    Read the full guide 

  • Alopecia areata (autoimmune hair loss)

    Alopecia areata is an autoimmune condition that can cause sudden, localised hair loss, often appearing as clearly defined patches. It may also affect eyebrows, eyelashes or beard areas.

    Its course can vary, with periods of regrowth and possible recurrence.

    Read the full guide 

Overlap and uncertainty are common

Hair loss does not always fit perfectly into one category, especially in early stages. Some people experience overlapping patterns, or notice that shedding reveals an underlying thinning pattern that was already developing.

That is why structured assessment focuses on pattern, timing and triggers, rather than assumptions based on appearance alone.

When to consider professional assessment

Consider speaking with a qualified clinician if you notice:

  • Sudden patchy hair loss, eyebrow/eyelash loss, or scalp inflammation

  • Rapid progression over weeks rather than months

  • Significant scalp symptoms (pain, burning, scaling)

  • Hair loss accompanied by other health changes

Identify your type of hair loss

If you are unsure which category best matches your situation, the TRIX Hair Check helps you clarify the most likely pattern using clinically informed questions.

Start the Hair Check (2 minutes)

Based on 20+ years of dermatological expertise

IMPORTANT: This page provides general orientation only. For detailed explanations, diagnostic context and condition-specific guidance, please consult the dedicated pages linked above.

Common questions about hair loss

Is hair loss always caused by the same underlying problem?

No. Hair loss is not a single condition. From a clinical perspective, it is a symptom that can result from different biological mechanisms, such as changes in the hair growth cycle, genetic sensitivity of hair follicles, or immune-related processes. Because these mechanisms differ, hair loss can vary in pattern, timing and progression.

Can different types of hair loss occur at the same time?

Yes. In practice, overlapping patterns are common. For example, increased shedding can make an underlying thinning pattern more noticeable, or a temporary disruption can occur alongside a longer-term process. This is why assessment focuses on pattern, timing and triggers, rather than assumptions based on appearance alone.

Does hair loss always mean it is permanent?

No. Some forms of hair loss are reactive and potentially temporary, while others tend to be progressive and long-term. The outlook depends on the underlying mechanism affecting the hair follicles. Identifying the most likely type helps set realistic expectations and guides which information is most relevant.

How can I tell which type of hair loss applies to me?

Visual signs alone are often not enough, especially in early stages. Structured assessment considers factors such as distribution, onset, progression and potential triggers. If you are unsure, a guided questionnaire like the TRIX Hair Check can help clarify which hair loss pattern is most likely and where to find more detailed information.