What is diffuse thinning and how to treat it

When you think of hair loss, known as alopecia, you may think of male pattern baldness: the receding hairline or hair loss at the top of the head that men often experience. Diffuse thinning describes hair loss that leads to fewer strands of hair across the scalp. It affects men and women. The good news: it’s often temporary or treatable.

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The first sign of diffuse thinning can be excessive shedding. You may see more of your scalp and less hair around the top or sides of your head. If you wear a ponytail, you may feel less hair to pull up. The hair strands may come out gradually or quickly in clumps (Malkud, 2015). 

But just because you notice hair strands out of place, that does not necessarily mean that you are experiencing diffuse thinning. While it can be stressful to see balls of hair in the shower or on your hairbrush, some hair loss is normal. In fact, it’s normal to lose 100 strands of hair a day. Humans have 80,000 to 120,000 hair follicles, and hair grows and falls out every 2-6 years (Murphrey, 2021; Ho, 2021).  

Additionally, washing hair doesn’t cause hair loss. It helps dislodge strands that were about to fall out. That’s why you’ll see more hair in the shower if you wash your hair once a week than if you wash it every day. However, if more than 100 hairs are falling out a day, it may be a sign of a problem (Asghar, 2020).

The causes of diffuse hair thinning range from genetics and medicines to stress, illness, and extreme dieting. Typically, it occurs when the hair growth cycle is thrown off. The normal cycle follows three phases for specific periods (Malkud, 2015; Ho, 2021):

1. Anagen phase (growth): 80%-90% of hairs are in this phase at a given time; active growth lasts 2-6 years.

2. Catagen phase (transitional): Less than 5% of hairs are in this phase at a given time; transition lasts about six weeks.

3. Telogen phase (resting): 10%-15% of hairs are in this phase at a given time; it lasts about 2-3 months before hairs fall out to make way for new hairs.

The following types of hair loss are the most common causes of diffuse thinning:  

Telogen effluvium 

Telogen effluvium (TE) is considered the most common cause of diffuse thinning. It’s a broad term and covers a wide variety of conditions with varying causes. TE occurs when anagen hair is pushed into the telogen phase too early. This type of hair loss results from the body experiencing a change, imbalance, or shock. It usually leads to thinning but not complete hair loss. The following are common TE triggers (Asghar, 2020; Hoover, 2020; Malkud, 2015):

• Hormonal changes (pregnancy, childbirth, stopping oral contraceptives)

• Stress (TE often occurs 2-3 months after extreme stress)

• Illness/trauma (e.g., fevers, COVID-19, invasive surgery, accident) (Mieczkowska, 2020)

• Weight loss (e.g., rapid or extreme weight loss, crash diets)

• Diet changes (caloric, fatty acid, or protein restrictions)

• Vitamin or mineral deficiencies (zinc, vitamin D, selenium, iron deficiency)

• Endocrine imbalances (e.g., hyperthyroidism, hypothyroidism) (Olszewska, 2010)

• Medicines (e.g., beta-blockers, ACE inhibitors, anticoagulants, androgens, retinoids, antidepressants) (Asghar, 2020; Everts, 2012)

• Poisoning (e.g., arsenic, mercury, thallium, lead, cadmium) (Aziz, 2015)

The hair loss with TE is noticed about 2-3 months after the shock or change. Hair usually begins to regrow about 3-6 months after shedding begins if the challenge to the body has resolved. The amount of shedding is generally less than 50% of the hair follicles. So, while clumps of hair may be shocking, TE doesn’t lead to complete baldness (Malkud, 2015).

Chronic telogen effluvium (CTE) is a little different. It lasts more than six months and affects mainly middle-aged women. What causes CTE is often not clear. Many cases do result in a shorter anagen phase. (Trueb, 2016; Shrivastava, 2009; Rebora, 2005; Shashikant, 2015). 

Anagen effluvium

The interruption of the anagen (growth) phase causes anagen effluvium (AE). Cancer medications are usually the causes of AE, but radiation and chemical toxins can also cause AE (Kanwar, 2013). Patients undergoing chemotherapy often see hair loss about two weeks after treatment. It usually starts growing back after about three months (Saleh, 2021).

Research shows that scalp cooling can reduce hair loss from chemotherapy, but it can have side effects like headaches. The American Cancer Society suggests that patients check with their oncologists if considering this approach (Rugo, 2021; Rugo, 2017). 

Male and female pattern hair loss

Androgenetic alopecia (AGA), also known as “pattern” hair loss or balding, is genetic. It’s marked by a shortened anagen phase and shrinking hair follicles - called follicle miniaturization (Ho, 2021). Male pattern hair loss usually begins with a receding hairline or hair loss at the crown of the head. But the pattern can vary. Men may also notice diffuse thinning of the hair across the top and sides of the head (Phillips, 2017).

For women, diffuse thinning around the center, front, and sides of the head is the hallmark of female pattern hair loss, marked by the miniaturization of hair follicles. This diffuse pattern can make it harder to diagnose this type from other hair loss conditions in women, such as telogen effluvium (Shrivastava, 2009).

Diffuse type of alopecia areata 

Alopecia areata (AA) occurs when the immune system attacks the hair follicle. It usually causes patches of hair loss. Two common variants—alopecia areata incognita and diffuse alopecia areata—cause diffuse thinning (Alessandrini, 2020). These types can be misdiagnosed with TE and androgenetic alopecia. Often AA is temporary, and hair will grow back. But it can be long-term (Pratt, 2017).

Overprocessing and styling 

Chemicals in dyes, bleaches, perms, and relaxers, along with excessive heat and styling, can damage the hair shaft down to the scalp. This type of hair loss is usually reversible once someone stops these harmful hair practices (Phillips, 2017).

A proper diagnosis is critical if you have unexplained hair loss because it could identify a medical condition like hypothyroidism. During a consult, expect a healthcare provider to discuss the following (Aboud, 2021):

• When did your hair loss start?

• How many hairs per day are falling out?

• Associated symptoms (hair loss elsewhere on the body, other)

• General health, recent illnesses

• Current diet, medications, supplements 

• Haircare practices (processing, styling, product use)

• Major events (childbirth, surgery, training, other)

• Stress levels (physical or mental stress)

• Family history (to check for a genetic predisposition for alopecia)

A physical exam and consult with a dermatologist may involve a variety of diagnostic approaches, such as (Asghar, 2020; Aboud, 2021; Mysore, 2020):

• Hair wash test: A healthcare provider will ask the person experiencing hair loss to wash their hair after waiting five days. Hair is collected and counted.

• Hair pull test: A small number of hairs are gently pulled from different spots on the head to determine the amount and type of hair loss.

• Visual analysis: Healthcare providers may use microscopy, dermoscopy, and trichoscopy to view the hair and scalp to help diagnose different types of hair loss.

• Scalp biopsy: Biopsies offer the best confirmation if a diagnosis is in question.

• Laboratory testing: Depending on the consult, various lab tests may help rule out or confirm underlying medical issues. Tests may check: blood count, iron levels, endocrine system/thyroid function, autoantibodies, various hormone levels, blood sugar, vitamin/nutrient levels, and help diagnose other medical conditions.

Healthcare providers should tailor hair loss treatment options to each person based on the cause of the hair loss and their desired outcome.

The following hair loss categories have different treatment approaches. 

Telogen effluvium (TE)

Usually, with TE, hair grows back. This may require reducing stress, improving diet, or addressing underlying health issues. A healthcare provider may suggest supplements or changes in diet to correct a nutritional deficiency. That said, taking excessive supplements can be harmful. Overdosing on vitamins A, E, and selenium, which are popular in many hair supplement formulas, can cause hair loss (Rebora, 2019).

If there is pain at the site of hair loss, a condition called trichodynia, a healthcare provider may prescribe topical corticosteroids (Asghar, 2020). 

Chronic telogen effluvium is often marked by a shortened anagen phase, similar to pattern hair loss but without the follicle miniaturization (Shashikant, 2015). For this reason, some treatments used to treat pattern hair loss are being used in cases of CTE. 

To boost regrowth, a dermatologist may suggest minoxidil (Rogaine) which improves blood flow to the scalp. Research is underway on the use of platelet-enriched plasma (PRP) and low-level laser therapy. These are designed to boost growth and have shown some positive results in cases of CTE (Mysore, 2020). 

Androgenetic alopecia (AGA)

Drug therapies. It’s important for men with diffuse thinning to rule out telogen effluvium as a possible cause. If it’s determined that the thinning is related to AGA, there are two FDA-approved drugs for men with male pattern hair loss: finasteride and topical minoxidil.

Finasteride (Propecia) and topical minoxidil (Rogaine) take about 4-6 months of treatment and continual use to retain hair growth. For women with female pattern hair loss, healthcare providers prescribe topical minoxidil and oral antiandrogens (Aboud, 2021, Ho, 2021).

Platelet-enriched plasma. A variety of studies have suggested that a process called platelet-enriched plasma (PRP) improves hair growth in those with male AGA and female pattern hair loss. PRP involves a blood draw, separating a person’s blood platelets, and injecting a condensed platelet solution into the scalp. The process calls for three initial monthly treatments, followed by maintenance treatments to retain growth every 3-6 months. Combining PRP with topical minoxidil was shown to improve results. But more extensive trials are needed to clarify how effective PRP is for hair loss (Gupta, 2019; Mercuri, 2021). 

Hair transplantation. It’s important to note that people with diffuse thinning may not be candidates for hair transplantation if they lack the thicker sections of permanent hair that can be transferred to bald areas (Ho, 2021). Those with diffuse androgenetic alopecia who are seeking a hair transplant may face the loss of transplanted hair if it’s not grafted from what’s considered a ‘safe donor area’ of their head (Kumaresan, 2018).

Alopecia areata (AA) 

All types of AA are inflammatory autoimmune conditions. Often the hair grows back without treatment. To treat AA, the American Academy of Dermatology suggests topical, injectable, or oral corticosteroids to reduce inflammation and minoxidil to restore hair (Lepe, 2021; Alessandrini, 2020; AAD, 2021; Zerbinati, 2018). JAKS inhibitors, which block inflammation, have shown some promise, though they do increase the risk for infections (Ramot, 2020; Santos, 2019).

AA is a non-scarring form of hair loss and may regrow and fall out at different times. Some autoimmune disorders, such as Lupus, can lead to scarring of the hair follicle. This stops hair from ever re-growing. Scarring alopecia should be diagnosed quickly to avoid permanent damage (Forouzan, 2020).

Some types of diffuse thinning are genetic and not preventable. However, there are ways to boost hair health that can help ward off many cases of hair loss:

• Avoid repeated harsh chemical hair treatments, heat, and over-styling (Phillips, 2017).

• Avoid overdosing on supplements like Vitamin A, E, and selenium (Guo, 2017).

• Build healthy hair with a good diet. A diet rich in protein, vitamins, minerals, and antioxidants can prevent deficiencies that can cause hair loss (Guo, 2017).

• Work with a healthcare provider to correct nutritional deficiencies or endocrine imbalances (Grover, 2013).

• Maintain a healthy weight (Grover, 2013).

• Try scalp massage, which can boost circulation to scalp hair (Koyama, 2016).

• Reduce stress; exercise and good sleep habits can help lower stress levels; stress-management programs may help (Rajoo, 2019; Wunsch, 2017; Choi, 2018).

• Monitor potential health problems with regular annual physicals and work with a healthcare provider to keep medical conditions in check (Phillips, 2017).

A variety of health problems can negatively impact hair health. If you notice problems with diffuse hair loss, contact your healthcare provider. Preventing hair loss or damage to hair follicles is easier than trying to restore hair later. Even if you’re not concerned about having hair, addressing unexplained hair loss can be a sign of a more serious medical condition.

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Current version

August 27, 2021

Written by

Kristin DeJohn

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.