Three observations narrow most hair-loss diagnoses: pattern, speed, scalp condition.

You don’t need a dermatologist to start the diagnosis. Three observations narrow most cases:

1. Pattern. Diffuse across the whole scalp? Concentrated at temples and crown? Sharp round/oval patches? Each suggests a different category.

2. Speed. Sudden shed 2–4 months after a trigger (illness, surgery, childbirth, stress)? Or gradual progression over years? The first is almost always telogen effluvium; the second is usually pattern hair loss.

3. Scalp condition. Smooth and clean? Or red, scaling, itching, painful? Inflammation suggests scarring alopecia, the most urgent category to identify, because anti-inflammatory treatment can halt progression but cannot reverse the damage.

Those three observations usually point to one cause. The cause dictates the workup, the urgency, and what actually helps.

Full diagnostic guide: regrowthindex.com/articles/whats-causing-my-hair-loss