Hair and nail disorders: common types and what they can signal

Finding more hair in the brush or a nail that has turned thick and discoloured can be worrying, and it is natural to ask whether it points to something deeper. Hair and nails are part of the skin's family of structures, and dermatologists evaluate both. This page describes three common kinds of hair loss and three common nail changes as medical sources present them, explains how they are usually evaluated, outlines general treatment themes, and notes when changes can signal other conditions. It does not diagnose or recommend treatment.

Androgenetic alopecia (pattern hair loss)

This is the most common form. MedlinePlus, the US National Library of Medicine's public health site, calls it a common form of hair loss in both men and women, also known as male pattern baldness or female pattern hair loss. It states that the condition affects an estimated 50 million men and 30 million women in the United States, and that more than 50 percent of men over age 50 have some degree of hair loss.

The pattern differs by sex. In men, MedlinePlus says, hair loss starts above both temples, so the hairline recedes into an "M" shape, and hair thins at the crown. In women, hair thins at the top of the head and the middle part widens; the hairline typically does not recede and total baldness is rare. MedlinePlus links the condition to hormones called androgens, and adds that genetic and environmental factors likely contribute, though most remain unknown.

Alopecia areata

Alopecia areata works differently. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) describes it as a disease in which the immune system attacks hair follicles and causes hair loss, usually on the head and face, often in small, round patches. Most people with it have no other symptoms. Most people develop it in their teens, twenties or thirties.

NIAMS states that emotional stress or illness may trigger it in people who are at risk, though usually there is no obvious trigger. It also lists related conditions: other autoimmune diseases such as psoriasis, thyroid disease and vitiligo, and allergic conditions such as hay fever and atopic dermatitis (see eczema and atopic dermatitis). Nail pitting, meaning tiny dents, occurs in some people, especially those with more extensive hair loss. There is no cure, NIAMS says, though treatments can help hair regrow more quickly.

Telogen effluvium

The third common type is the one most often tied to a recent event. DermNet, a clinical reference, describes telogen effluvium as a common, temporary, non-scarring form of diffuse hair loss in which a shock to the body causes many resting (telogen) hairs to shed. The triggers it lists include childbirth, acute or chronic illness especially with fever, surgery, psychological stress, weight loss or poor nutrition, certain medications, thyroid disorders and stopping the contraceptive pill.

Timing is the clue. DermNet says increased shedding usually begins about 2 to 4 months after the trigger, so the connection is easy to miss, and that it typically peaks and then tapers back to normal over 6 to 9 months. Hair usually regrows once the trigger is removed, although recovery can be incomplete in some people and a chronic form can last for years. DermNet adds that Beau lines in the nails can help estimate when the shock occurred.

How hair loss is evaluated

Because different types need different handling, the first task is to work out which type is present. For alopecia areata, NIAMS describes examining the areas of hair loss and the nails, inspecting hair and follicle openings with a handheld magnifying device, and reviewing medical and family history. Blood tests or a skin biopsy may be used to rule out other causes of similar hair loss; skin biopsy, what to expect describes the procedure.

For telogen effluvium, DermNet says the diagnosis is usually made from clinical features, specifically diffuse thinning across the scalp and a hair pull test that pulls out many resting hairs. A scalp biopsy is rarely needed. See also how dermatologists diagnose skin conditions.

General treatment themes for hair loss

The themes vary by type. For alopecia areata, NIAMS names corticosteroids (often as injections for patchy loss), immunosuppressants, other disease-modifying medicines, and Janus kinase (JAK) inhibitors, which it says are approved to treat adult patients with severe alopecia areata. It also stresses that many people regrow hair without treatment and that some choose hairpieces or wigs.

For telogen effluvium, DermNet's themes are gentle hair handling, addressing any scalp or hormonal problem, adequate nutrition, correcting measured deficiencies and recognising the psychological impact. The sources used here do not set out treatment options for androgenetic alopecia, and since options differ and the choice is individual, that is best discussed with a clinician.

Fungal nail infection

Turning to nails, the most familiar problem is fungus. The American Academy of Dermatology says the first sign is usually a change in the nail, such as a different colour on part of it. Other signs include a brittle nail that cracks or splits and buildup under a discoloured nail. It often starts on the big or second toe, and the surrounding skin may be red.

The Academy states that sometimes testing is needed to diagnose nail fungus and treat it effectively. That matters because other nail conditions can look similar, as the next sections show. On treatment, it says prescription medication, applied to the nail or taken as a pill, is needed to clear a fungal nail infection, that mild infections caught early are more treatable, and that scraping or filing the nail does not remove the fungus. Nail changes can remain after the infection clears because the nail must grow out, which may take months or over a year for a big toenail.

Psoriatic nail changes

Psoriasis can affect nails. DermNet reports that nail psoriasis affects 90 percent of patients with chronic plaque psoriasis at some time in their life. Signs include pitting, white nails, longitudinal ridges or splits, Beau lines, crumbling, and changes under the nail such as lifting of the nail (onycholysis) and splinter haemorrhages. For the underlying skin condition, see psoriasis explained.

DermNet notes that nail disease may raise the risk of developing psoriatic arthritis, and that diagnosis is usually clinical. Because fungal infection can coexist, it says nail clippings should be tested for fungus. Treatment themes it names include reducing nail trauma, topical medicines, systemic medicines, and non-drug approaches such as phototherapy.

Ridges and when nail changes signal other conditions

Many people notice lines in their nails. Mayo Clinic says vertical nail ridges, which run from the cuticle to the tip, are fairly common and nothing to worry about, and that with age they may become more numerous or prominent because of changes in cell turnover within the nail. It advises consulting a health care provider if fingernails change colour or horizontal ridges develop, since these changes could indicate an underlying health condition.

The sources above give other examples: Beau lines marking a past shock in telogen effluvium, pitting in alopecia areata and psoriasis, and thyroid disorders or poor nutrition among the listed triggers of telogen effluvium. None of this means a change is serious by default. It means that a persistent or unexplained change deserves a proper look, since the same-looking nail can have quite different causes.

Honest limits

These conditions are common but not simple. Several can look alike, treatments depend on the exact diagnosis, and results are not guaranteed: hair may regrow slowly or incompletely, and nails take many months to grow out. The frequency figures here come from US data and may not match other populations.

This page has not been medically reviewed and cannot say what is behind any particular change. Individual care varies, and your own doctor or specialist has the final word.

The short version

Hair loss and nail changes have many causes, from inherited pattern hair loss and immune-driven patches to temporary shedding after a shock, and from fungus to psoriasis or ordinary ageing. Evaluation starts with examining the hair, scalp and nails, sometimes with tests. A persistent or unexplained change is worth professional assessment, because the right treatment depends on the right diagnosis.