Because there are many types of hair loss, finding the cause can be challenging. This review will cover the most common causes of hair loss occurring on normal unscarred scalp skin. The medical term for hair loss is alopecia.

Most hair loss is not associated with systemic or internal disease, nor is poor diet a frequent factor. Hair may simply thin as a result of predetermined genetic factors and the overall aging process. Many men and women may notice mild physiologic thinning of hair starting in their 30s and 40s. Life vicissitudes, including illness, emotional trauma, protein deprivation (during strict dieting), and hormonal changes like those in pregnancy, puberty, and menopause may cause hair loss.

Several health conditions, including thyroid disease and iron deficiency anemia, can cause hair loss. While thyroid blood tests and other lab tests, including a complete blood count (CBC), on people who have ordinary hair loss are usually normal, it is important to exclude treatable causes of hair loss.

What types of doctors treat hair loss?

Such basic health screening can be done by a family physician, internist, or gynecologist. Dermatologists are doctors who specialize in problems of skin, hair, and nails and may provide more advanced diagnosis and treatment of hair thinning and loss. Sometimes a scalp biopsy may be necessary.

Although many medications list “hair loss” among their potential side effects, most drugs are not likely to induce hair loss. On the other hand, cancer chemotherapy and immunosuppressive medications commonly produce hair loss. Complete hair loss after chemotherapy usually regrows after six to 12 months.

How do physicians classify hair loss?

There are numerous ways to categorize hair loss. One must first examine the scalp to determine if the hair loss is due to the physical destruction and loss of hair follicles (scarring alopecia). If the scalp appears perfectly normal with plenty of empty hair follicles, this is called non-scarring hair loss. On the other hand, the follicles are permanently destroyed in scarring hair loss. Non-scarring hair loss can also be seen in situations where there is physical or chemical damage to the hair shaft resulting in breakage. Occasionally, it may be necessary to do a biopsy of the scalp to distinguish these conditions. Sometimes, a physician may pull a hair to examine the appearance of the hair shaft as well as the percentage of growing hairs (anagen phase). This article will concentrate on the non-scarring types of hair loss.

Patchy hair loss

Some conditions produce small areas of hair loss, while others affect large areas of the scalp. Common causes of patchy hair loss are

  • alopecia areata (small circular or coin size patches of scalp baldness that usually grow back within months),
  • traction alopecia (thinning from tight braids or ponytails),
  • trichotillomania (the habit of twisting or pulling hair out),
  • tinea capitis (fungal infection), and
  • secondary syphilis.

Diffuse hair loss

Some common causes of diffuse hair loss are

  • pattern alopecia,
  • drug-induced alopecia,
  • protein malnutrition, and
  • systemic disease-induced alopecia (cancer, endocrine disease, and telogen effluvium).

What treatment is there for hair loss in men?

There are few scientifically proven and FDA-approved treatments for hair loss. There are thousands of unproven claims and products to help with hair regrowth. Many conditioners, shampoos, vitamins, and other products claim to help hair grow in some unspecified way. Nioxin has been a popular brand of shampoo for hair loss, but there is no compelling evidence showing it is any more effective than regular shampoos. These products are usually harmless but generally not scientifically proven and therefore potentially useless. To slow down hair loss, there are at least four potentially effective, basic options. These include medications like Minoxidil, and Propecia, which are for long-term use. Stopping these drugs does not seem to worsen or exacerbate the prior hair loss. The patient will simply revert to the state he would have been in had he never started treatment.

  • Minoxidil (Rogaine): This topical medication is available over the counter, and no prescription is required. It can be used in men and women. It works best on the crown, less on the frontal region. Minoxidil is available as a 2% solution, 4% solution, an extra-strength 5% solution, and a new foam or mousse preparation. Rogaine may grow a little hair, but it’s better at holding onto what’s still there. There are few side effects with Rogaine. The main problem with this treatment is the need to keep applying it once or twice daily, and most men get tired of it after a while. In addition, minoxidil tends to work less well on the front of the head, which is where baldness bothers most men. Inadvertent application to the face or neck skin can cause unwanted hair growth in those areas.
  • Finasteride (Propecia): This medication is FDA approved for use in only men with androgenic hair loss. Finasteride is in a class of medications called 5-alpha reductase inhibitors. It is thought to help reduce hair loss by blocking the action of natural hormones in scalp hair follicles. Propecia is a lower-dose version of a commercially available drug called Proscar that helps shrink enlarged prostates in middle-aged and older men. Women of child-bearing potential should avoid finasteride. Propecia 1 mg tablets are available by prescription and taken once daily. Propecia may grow and thicken hair to some extent for some people, but its main use is to keep (maintain) hair that’s still there. Studies have shown that this medication works well in some types of hair loss and must be used for about six to 12 months before full effects are determined. This medication does not “work” in days to weeks, and its onset of visible improvement tends to be gradual. It may be best for men who still have enough hair to retain but also can help some regrow hair. Possible but very unlikely side effects include impotence or a decreased sex drive (libido). Studies have shown that these side effects were possibly slightly more common than seen in the general population and are reversible when the drug is stopped. The cost is about $70-$100/month, which is generally not reimbursed by most health insurers.
  • A group of topical medications called prostaglandin analogs have recently began undergoing testing for potential hair regrowth. They may be used in men and women. These drugs are not currently FDA approved for scalp hair loss. Currently, these are primarily used for eyelash enhancement. One of the new medications is called bimatoprost (Latisse). Further testing and studies are required to assess the efficacy of these products in scalp hair loss. Bimatoprost solution is sometimes used off-label for help in selected cases of hair loss. It is currently FDA approved for cosmetic eyelash enhancement. Studies have shown it can treat hypotrichosis (short or sparse) of the eyelashes by increasing their growth, including length, thickness, and darkness. This medication is also commercially available as Lumigan, which is used to treat glaucoma. It is not known exactly how this medication works in hair regrowth, but it is thought to lengthen the anagen phase (active phase) of hair growth. Interestingly, during routine medical use of Lumigan eyedrops for glaucoma patients, it was serendipitously found that eyelashes got longer and thicker in many users. This led to clinical trials and the approval of cosmetic use of Latisse for eyelashes.