8 Illnesses That Cause Hair Loss

File hair loss under things you don’t want to deal with, right up there with making returns and picking an insurance plan. Sigh. Being an adult seemed way more fun in the third grade, right?

Still, it’s important to understand the causes of hair loss so you can figure out the right course of action to keep those hairs on your noggin. In this article, we’ll cover medical conditions that could lead to hair loss, plus potential treatments to help promote new hair regrowth.

8 Illnesses That Cause Hair Loss

If you’ve been seeing a receding hairline or some overall thinning, you have to figure out the root cause to know how to treat it. Several illnesses and medical conditions can be a cause of hair loss, including androgenic alopecia, alopecia areata, nutritional deficiencies, fungal infections, autoimmune disorders, cancer, diabetes and trichotillomania.

Here’s what to know.

Androgenetic Alopecia

This common form of hair loss can affect up to 50 percent of men. That’s a lot of dudes, for real. Sometimes called male pattern hair loss or male pattern baldness, the condition is primarily caused by a predetermined genetic sensitivity to androgens. 

In androgenetic alopecia, a sensitivity to dihydrotestosterone (DHT) causes hair follicles to become smaller and shorter due to a progressively shorter anagen phase, resulting in thinner and shorter hair.

Hair loss tends to occur in bitemporal (the sides or temples of your hairline), vertex (the crown of your head) and mid-frontal scalp areas. This non-scarring alopecia may be reversible if caught early enough.

For a deeper dive, see our guide to androgenetic alopecia.

Alopecia Areata

This autoimmune disease occurs when the immune system attacks anagen hair follicles and sends them prematurely into the catagen phase (when hair stops growing) of your hair growth cycle.

The cause of alopecia areata is not yet understood, but some triggers are thought to include emotional or physical stress, vaccines, drugs and viral infections. While alopecia areata often appears on the scalp, it can also move to other parts of the body.

Read our blog to learn why this happens and how to stop alopecia from spreading. Onset of alopecia areata usually occurs quickly with patchy bald spots (sometimes called patchy hair loss), as opposed to the gradual thinning typically seen in androgenetic alopecia. It’s been linked to other medical conditions, like thyroid disease, vitiligo, psoriasis, lupus erythematosus, inflammatory bowel disease and rheumatoid arthritis.

Learn more about all the different alopecia types in our comprehensive guide.  

Nutritional Deficiencies

Truly, we wish that Cheetos® were one of the food groups to include in a healthy diet. While they can have their place, a balanced diet filled with vitamins and essential nutrients is critical for healthy hair growth. Like Batman and Robin, they go together.

With that said, nutritional deficiencies can influence both hair growth and structure. Certain vitamin deficiencies can even cause hair loss.

Androgenetic alopecia and telogen effluvium are two prevalent forms of hair loss. Research has indicated that adding small amounts of vitamin D to your diet can help alleviate symptoms associated with these conditions.

We also like soaking up some sunshine in the pursuit of better hair. Bookmark our guide to vitamin D and hair loss for more hair knowledge.

Other issues like iron deficiency can lead to anemia hair loss. Biotin deficiency has been linked to thinning hair as well. Talk to your healthcare provider and get blood tests done to see where your levels fall. If necessary, they can recommend the proper supplements for optimal hair growth.

If you’ve gone through sudden weight loss, you may also experience telogen effluvium hair shedding. Learn more about hair loss and diet in our guide.

Fungal Infections

Fungus is no fun when it’s growing in your bathroom shower, and it’s certainly not a party when it’s growing on your scalp — ugh.

Scalp fungus (or tinea capitis) is a fungal infection that affects your scalp hair. It also goes by the somewhat alarming names herpes tonsurans and ringworm.

The main culprits behind this condition are the dermatophyte species Microsporum and Trichophyton. These fungi have the ability to infiltrate the outer root sheath of your hair follicles and can even make their way into the hair shaft itself. This form of scalp inflammation can lead to hair thinning.

Autoimmune Disorders

A number of autoimmune conditions like thyroid disorders, lupus erythematosus and irritable bowel syndrome can take a toll on your hairline. By the way, we have a full guide on autoimmune diseases that cause hair loss, so bookmark that for some more digging.

Hair loss is also among the common signs of SLE (systemic lupus erythematosus), with upwards of half of patients experiencing it over the course of their illness.


While cancer itself doesn’t typically cause hair loss, the medical treatments and drugs used to treat it can cause thinning. Anagen effluvium is a form of hair loss often linked to chemotherapy.

This condition occurs when the anagen hairs are exposed to a harmful or inflammatory substance, which causes the hair shaft to break. Anagen effluvium is also known as chemotherapy-induced alopecia.


Having diabetes doesn’t just mean you have to watch out for sweets. Insulin resistance can have various side effects, one being hair loss.

Insulin is present in hair follicles and may be involved in regulating androgen metabolism and the hair growth cycle, both of which are important factors in male pattern baldness.

The miniaturization of hair follicles (when your hair follicles get smaller) can also be a factor of diabetes. If you’ve recently been diagnosed with diabetes, you can learn more in our guide to diabetes hair loss.


Trichotillomania (TTM) is a long-term impulse-control disorder involving compulsive hair pulling, which can lead to visible hair loss. Onset typically appears in childhood or the teenage years.

It’s often seen along with other mental health disorders, such as anxiety disorders, eating disorders, substance use disorders, mood disorders and personality disorders.

Learn more about stress and hair loss in our guide.

It’s official. Hims is a hit.

Now after 5 months I’m able to style waves first time in 10 years!  

Bryan, 28

Verified review

After 7 months, I have experienced incredible results and my hair is back.

Tony, 32

Verified review

Cost effective and affordable. My hair keeps growing thicker, fuller, and at a fast rate.

Ryan, 29

Verified review

In just as little over two and half months, I can really see the difference in thickness and in color.

Parbhu, 28

Verified review

It has helped boost my confidence as well as give me a full head of hair to play with. I am so pleased.

Michael, 33

Verified review

I decided to jump right in and I'm so glad I did. I definitely feel ten years younger!

Jesse, 36

Verified review

4-months strong and my confidence boosted back up to 100% using Hims, future me really does thank me.

Giovanny, 23

Verified review

Hims allowed me to walk down the aisle confident and looking great.

Alexander, 32

Verified review

I tried several different options before but Hims combined approach of all four methods by far created the best results.

Brian, 48

Verified review

The results speak for themselves and I recommend it to all of my friends.

Al, 54

Verified review

I notice a huge change in the overall health and fullness of my hairline.

Seth, 27

Verified review

In just as little over two and half months, I can really see the difference in thickness and in color.

Milton, 36

Verified review

Hims has been the greatest confidence boost, no more bald jokes! I look and feel so much younger.

Mike, 34

Verified review

Before/after images shared by customers who have purchased varying products, including prescription-based products. Customers were compensated for their testimonials. These customers’ results have not been independently verified. Individual results will vary.

Is Hair Loss From an Illness Treatable?

Depending on the illness and the form of hair loss, treatments can vary. Your dermatologist or healthcare provider can determine which type of hair loss treatment will best work with your medical condition.

Here are a few options they might recommend:

  • Finasteride. FDA-approved to treat androgenetic alopecia, this oral treatment is a 5-alpha-reductase isoenzyme that helps block the conversion of hormones responsible for thinning hair seen in androgenetic alopecia.

  • Topical finasteride & minoxidil spray. This quick-drying spray combines two gold-star treatments, finasteride and minoxidil, to effectively treat shrinking hair follicles from multiple pathways.

  • Minoxidil 5% foam. Minoxidil is FDA-approved for androgenetic alopecia. It’s also used off-label to treat various hair loss disorders, including alopecia areata, telogen effluvium, anagen effluvium and chemotherapy-induced alopecia. Studies have shown improved hair growth within various causes of hair loss. A 2% minoxidil solution is also available for those who may have more sensitive scalps.

Shop by treatment options

No matter the treatment plan, the best place to start is somewhere. Early action is the best hair loss prevention.

No-pill option

Hair Hybrids by Hims

The Combination Hair Loss Spray

From £26/month

This spray treatment combines two active ingredients used for treating hair loss and hair regrowth.

Important Safety Information

No-pill option

Hair Hybrids by Hims

The Combination Hair Loss Serum

From £26/month

This serum treatment combines two active ingredients used for treating hair loss and hair regrowth.

Important Safety Information

Generic Treatment

Finasteride & Minoxidil Combo Kit

From £30/month

This combo kit includes two treatments. The once-daily tablet is clinically proven to stop hair loss. The alcohol-free topical serum, applied twice daily, is used for hair regrowth.

Important Safety Information

Generic Treatment


From £23/month

This once-daily tablet is clinically proven to stop hair loss.

Important Safety Information

Hair Hybrids by Hims

Alcohol-free Minoxidil Serum

From £21/month

This alcohol-free topical serum, applied twice daily, is used for hair regrowth

Important Safety Information

Illnesses That Cause Hair Loss: Next Steps

From nutritional deficiencies to hypothyroidism and diabetes, many medical conditions can cause hair loss. Here’s what to keep in mind:

  • Make a move. Whether you’re noticing signs of male pattern baldness or are having more concerning issues like insulin resistance, don’t just ignore your symptoms. Things won’t just magically go away (except money, which seems to disappear pretty quick).

  • Speak with a pro. While you may be used to Googling everything or asking your best bud for advice, our rec is to speak with a dermatologist or another healthcare professional if you’re noticing hair loss. You want to rule out any underlying causes and get the appropriate attention and care for your condition. Your provider can determine the right hair loss treatments you may need.

  • Get treated. Whether it’s a combination of therapies, like medication for your illness, a hair loss treatment or supplements, treatment options can help slow down or even reverse hair loss. For instance, minoxidil has shown success in varying forms of hair loss conditions.

If you’re ready to get started, take this easy quiz to set up an online hair consultation.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment or medication.

Hair loss treatment for a long term solution

Clinically approved options available

Thousands of happy customers

Get started