Medically reviewed by Angela Sheddan, DNP, FNP-BC
Written by Our Editorial Team
Last updated 8/21/2021
Hair loss comes in many forms, from a receding hairline to a bald match that develops near the crown of your scalp.
One of the most common forms of hair loss is diffuse thinning — spread out hair loss that affects your entire scalp.
Instead of only affecting a certain area, such as your hairline or crown, diffuse thinning can give your entire head of hair a thin, “see-through” appearance.
Below, we’ve explained what diffuse thinning is, as well as the common signs that you may spot if you have this form of hair loss.
We’ve also listed the most common causes of diffuse thinning, as well as the steps that you can take to stimulate hair growth and restore your hair’s normal thickness and density.
Diffuse thinning, or diffuse hair loss, is a form of hair loss in which hair falls out from all areas of your scalp, causing your hair to take on a thin, low-density appearance.
Male pattern baldness, the most common cause of hair loss in men, usually starts to develop as a receding hairline or bald spot at the crown.
In contrast, diffuse hair loss usually affects the entire scalp, without causing a clear receding hairline or other distinct pattern.
Like other forms of hair loss, diffuse thinning can have a noticeable effect on the appearance of your hair and your quality of life.
Like other types of hair loss, diffuse thinning can appear suddenly or develop over the course of several months.
If you’re experiencing diffuse hair loss, you may notice the following signs and symptoms:
Reduced hair density. The most obvious sign of diffuse hair loss is visibly thin hair. You may notice that your hair looks less dense than normal, with fewer hairs at your hairline, midscalp and crown
Easily visible scalp. As your hair density decreases, your scalp may become easier to see. This sign is often especially visible when your hair is wet, or when you look at your scalp under bright, downward-facing light.
Excessive hair shedding. It’s normal to lose between 50 and 100 hairs each day as a result of your hair’s natural growth cycle. If you have diffuse thinning, you may start to lose more hair than this on a daily basis. A common sign of excessive hair shedding is a large number of hair strands that can be seen on your pillow case, in your bed sheets or around your shower drain.
Several different issues can cause or contribute to diffuse thinning. One of the most common is a form of hair shedding called telogen effluvium.
Telogen effluvium develops when a large amount of your hairs prematurely enter the telogen, or resting, phase of the hair growth cycle.
Healthy hair goes through a multi-phase cycle as it grows to its full length. In the anagen phase, each hair grows from the hair follicle to its full length over the course of two to six years.
The hair then enters into the catagen phase — a transition phase in which the hair stops actively growing.
Finally, the hair enters into the telogen phase, during which growth stops and the hair is eventually replaced by a new strand of anagen hair.
Normally, 85 percent to 90 percent of the hair on your scalp is in the anagen phase at any time, with the remaining hair in the telogen phase.
Telogen effluvium involves a large percentage of your hairs — often as much as 70 percent of all anagen hairs — prematurely entering into the telogen phase and shedding.
Most cases of telogen effluvium develop in response to physiologic stress, which can be caused by a variety of different factors.
Events that may trigger telogen effluvium include:
Illnesses that cause fever
Infections, major surgery or other injuries
Sudden changes in hormone levels
Severe or ongoing stress, or a traumatic event
Thyroid conditions, such as hypothyroidism
Crash diets that significantly reduce food intake
Nutritional deficiencies, such as low protein intake or iron deficiency
Medications, such as beta-blockers, retinoids, anticoagulants and others
When telogen effluvium occurs, hair loss usually isn’t immediate. Most of the time, the affected hairs will stop growing for one to six months, after which they’ll shed as they enter back into the anagen phase and detach from the scalp.
Hair shedding from telogen effluvium isn’t permanent — typically, your hair will start to grow back once the underlying issue is treated.
Our full guide to telogen effluvium goes into greater detail about how telogen effluvium develops and the symptoms it can cause.
Although telogen effluvium is a common cause of diffuse thinning, it isn’t the only issue that can cause this type of hair loss. Other potential causes of diffuse thinning include:
Male pattern baldness. Male pattern baldness can cause a receding hairline, balding at the crown and/or diffuse hair loss that affects most of your scalp. Men in the later stages of the Norwood Scale often have visible, significant diffuse thinning.
Unlike telogen effluvium, which typically causes temporary shedding, hair shedding from male pattern baldness needs to be treated quickly to prevent permanent hair loss.
Alopecia areata incognita This is a form of alopecia areata that causes diffuse, sudden hair shedding. It can develop over the course of a few weeks and is often misdiagnosed as telogen effluvium or male pattern baldness.
Diffuse alopecia areata. This form of alopecia areata is very similar to alopecia areata incognita, but occurs over a longer period. It also causes diffuse thinning that can affect the entire scalp.
If talking about hair loss in women, female pattern hair loss can also cause diffuse thinning. This type of female pattern hair loss usually causes hair loss around the scalp and part line (the area of the scalp where the hair splits into a left-facing and right-facing natural hair line), which can eventually progress to diffuse thinning across the scalp.
However, it’s worth noting that while diffuse hair thinning is a prominent feature of female pattern hair loss, it’s not the key determining factor in diagnosing female pattern hair loss.
Like other forms of hair loss, diffuse thinning is almost always treatable with medication, lifestyle changes, hair loss products or a combination of different approaches.
We’ve discussed the most effective ways to treat diffuse thinning below.
When diffuse thinning is caused by telogen effluvium, it will usually improve on its own after you identify the causative event and take steps to treat the issue that’s causing your loss of hair.
This could mean making changes to your use of certain medical treatments and medications, adjusting your diet, reducing stress or simply resting and recovering after an injury or surgery.
If you think that you might have telogen effluvium, it’s best to talk to your healthcare provider or schedule an appointment with a dermatologist.
They’ll be able to test your hair for signs of telogen effluvium using a pull test and biopsy. Many common causes of telogen effluvium can be identified with a complete blood count, thyrotropin test and other quick and convenient blood tests.
Minoxidil is a topical hair loss medication that’s available as a liquid or foam. It works by shifting hairs into the anagen phase, or growth phase, of the hair growth cycle and by stimulating the blood supply to your scalp.
If you have diffuse hair loss, applying minoxidil to your scalp often helps to stimulate growth and produce thicker, denser hair.
In a 12-month study, 84.3 percent of balding men who used minoxidil rated it as “very effective,” “effective” or “moderately effective” at promoting hair regrowth.
We offer minoxidil liquid and minoxidil foam online. You can find out more about what to expect from minoxidil in our guide to how long minoxidil takes to start working.
Finasteride is a prescription hair loss medication. It comes in tablet form and works by inhibiting the effects of 5-alpha reductase, an enzyme that converts testosterone into dihydrotestosterone (DHT).
DHT is a hormone that’s responsible for miniaturizing hair follicles in the scalp and causing male pattern baldness.
Finasteride is very effective, but only for hair loss that’s caused by DHT. In one study published in the Journal of the American Academy of Dermatology, researchers found that men who used finasteride for two years experienced a 15.8 percent increase in vertex scalp hair count.
We offer finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.
Right now, FDA-approved hair loss medications such as minoxidil and finasteride are the most effective treatment options for thinning hair.
However, other hair growth products can also help to control excessive shedding and promote healthy hair growth:
Growth-promoting shampoo. Many shampoos are formulated for stronger hair growth, with ingredients such as saw palmetto and ketoconazole. Our Hair Thickening Shampoo is designed to target DHT buildup on the scalp and support other hair loss treatments. Our guide to the best shampoos for thinning hair goes into more detail about ingredients to look for in a growth-promoting shampoo.
Biotin and other hair growth vitamins. As we’ve covered in our full guide to essential vitamins for healthy hair, several vitamins and minerals play key roles in the process of growing thick, strong and healthy hair. Our Biotin Gummy Vitamins are rich in biotin, niacin and several other essential vitamins for optimal hair growth.
Several different forms of hair loss can cause diffuse thinning, including telogen effluvium, male pattern baldness and autoimmune forms of hair loss such as alopecia areata.
Depending on its cause, diffuse thinning may develop as thinning of hair that affects your entire scalp evenly, or as a pattern of hair loss with thinning in specific areas.
If you’ve noticed your hair looking thinner than normal, it’s important to talk to your healthcare provider or schedule an appointment with a dermatologist to identify the cause.
Most of the time, hair loss treatments such as minoxidil and finasteride can stop hair loss and prevent diffuse thinning from getting worse.
Worried you’re going bald? Our guide to the early signs of balding lists common signs of male hair loss that you may notice if you’re beginning to lose your hair, as well as the steps that you can take to slow down, stop or reverse most types of hair loss.
Insider tips, early access and more.