Hair loss has causes. Start by finding yours.

Hair loss can be hormonal and hereditary, triggered by illness, stress, surgery, weight loss or medication, driven by inflammation and scarring, or caused by a scalp condition or nutritional issue. Some types are reversible; some are not, though progression can often be slowed.

Two patterns account for most cases: androgenetic alopecia, meaning hormonal and age-related thinning, and telogen effluvium, meaning a shedding phase that follows a physiologic stress. Rapid weight loss, including on GLP-1 medications, is an increasingly common trigger.

Scarring forms of hair loss behave differently and are time-sensitive, because follicles that are lost cannot be recovered. That is the main reason not to wait and see for too long.

• Gradual widening of the part or thinning at the crown
• A receding frontal hairline
• Noticeably increased shedding in the shower or on the pillow
• Round patches of complete hair loss
• Itching, burning, tenderness, scaling or visible scalp changes
• Loss of the hairline with smooth, shiny scalp, which suggests a scarring process

Topical therapy. Minoxidil, ketoconazole, tretinoin, topical anti-inflammatories and topical JAK inhibitors, depending on diagnosis.

Oral medication. Minoxidil, spironolactone, finasteride or dutasteride, JAK inhibitors and anti-inflammatory medication for selected diagnoses.

In-office procedures. Microneedling with platelet-rich plasma or exosomes, corticosteroid injections and low-level light therapy.

Supplements and products. Honest guidance on what has evidence behind it and what does not, so you are not spending money on hope.

Workup. Laboratory evaluation and scalp biopsy where these will change the plan.

Evaluation includes a detailed history — timing, pattern, family history, medications, recent illness or weight change, and hair care practices — and examination of the scalp and hair, often with a dermatoscope and a gentle pull test.

Laboratory work is frequently useful. A scalp biopsy may be recommended when a scarring process is suspected or the diagnosis is unclear; biopsies are performed with Dr. Gaul and can typically be billed to insurance.

Please note that insurance does not cover the treatment of androgenetic alopecia or telogen effluvium, the two most common types. These are seen as cash-pay visits: $250 for an initial visit and $150 for follow-up.