Hair Care

8 Illnesses That Cause Hair Loss, Based On Research

Are there really illnesses that cause hair loss? We dug through journals, research papers, and every credible resource online to answer that question and we hope you find what you’re looking for in our findings.

A variety of conditions can lead to hair loss and it might happen at a very rapid rate, researches have shown hair loss can occur to just your scalp or the entire body.

Hair loss can appear in different ways, either suddenly or gradually depending what’s causing it. Since they are numerous illness that can be categorized to hair loss, a biopsy of the scalp (1), can help to detect the cause.

Some hair loss can take place without any form of a scar on your scalp, which is called non-scarring hair loss, it means there is physical or chemical damage to the hair shaft resulting in the breakage but in the case of scarring, then they are some illness they might have caused it.

This posts will give you a detailed synopsis of illness that is causing hair loss based on research however it is important to know how hair loss can be diagnosed.

How Is Hair Loss Diagnosed?

Hair loss does occur from exposure to hair infections and might be back to normal in a couple of days with the right hair treatments but if it occurs it rapid succession comes with other symptoms then you should visit your doctor or dermatologist, who will, in turn, perform some tests which might fall into any of these three below (2).

  1. Blood test: This is to help uncover medical conditions related to hair loss.
  2. Pull test: Your doctor will gently pull several dozen hairs to see how many comes out and the hairs are screened under a microscope to help understand the cause of the hair loss (3).
  3. Scalp biopsy: Your doctor scrapes samples from the skin or from a few hairs plucked from the scalp to examine the hair roots.

Any of these diagnoses will help point into the right direction of what condition could have lead to hair loss.

Illnesses That Cause Hair Loss, According to Science

Numerous reasons can be the underlying cause of hair loss but persistent hair loss have been known to be associated mainly to some of this illness.

1. Alopecia Areata

Alopecia Areata illness that causes hair loss
Image Source: Yale Medicine

Alopecia areata is an autoimmune disease. which develops when the immune system mistakes healthy cells for foreign substances and attacks the hair follicles.

Alopecia is the umbrella name for serious hair loss that starts with gradual thinning on of the head and might eventually develop in to complete loss of hair. This is the most common type of hair loss, it affects both men and women as they age.

It usually starts with a  circular or patchy sudden loosening of hair afterward patch of scaling spread over the scalps (4).

Alopecia areata can also happen when recovering from surgery or from reaction to a medication. There are some treatments that can help but the condition itself can’t be cured (5). There are several kinds of alopecia but all come with hair loss as major symptoms.

What Are The Treatments And Medications Of Alopecia?

There is no treatment guaranteed to completely cure alopecia but based on research, here are some things that could help.

  • Tropical Creams And Lotions: There are over the counter drugs that can restore some hair growth, especially in those with hereditary hair loss. It is applied directly to the scalp (6). These medications might take some months before working (7).
  • Using Hair Weaves Or Wig: Some weaves can be used to cover the part of the head that has been affected or mostly wigs are used, this would help with the exposure. A treatment that has been known to help especially when avoiding public awareness.
  • Surgery: Surgery is usually the last considered option especially if it is the worst form of alopecia which involves the loss of hair on all parts of the body (8), the surgery is known as graft surgery, your dermatologist or doctor will give you a break down of the procedure to enlighten you on the merits and demerits of it.

2. Disease Of The Thyroid

The disease of the thyroid can range from a small harmless enlarged gland, goiter (9), that needs to treatment to a large abnormal thyroid which is excessive production of hormones in the system with hair loss as a major cause of concern.

Thyroid disease can develop into life-threatening cancer, the thyroid is in charge of producing hormones that regulate a lot of activities in your body.

The disease of the thyroid can cause it to produce too much or too little of the hormone, depending on how little much or how little your thyroid makes, it can cause you to always feel weak or gain excess weight (10).

3. Iron Deficiency Anemia

eating healthy

This would happen when your body does not have enough iron to provide hemoglobin, which will, in turn, limit the proper function of the body system and cause you to feel ill, fatigue and fever are mostly its symptoms but as these irons are needed for your hair too, it eventually starts to fall off.

Iron deficiency anemia might not become serious if proper care is taken on time.

Hair loss can’t be avoided when suffering from iron deficiency anemia. Other symptoms associated with hair loss are;

  • Paleness of the skin and hair scalp
  • Feeling very tired at all occasions, fatigue is actually the most common symptoms
  • Shortness of breath
  • Headaches that might lead to migraine and dizziness.

Iron deficiency anemia can be prevented by eating foods high in iron and taking iron supplements, blood tests will help determine how serious it is.

4. Secondary Syphilis

hair loss illnesses
Image: Groom + Style

Not all form of syphilis might cause hair loss but the chronic one will. Syphilis is a sexually transmitted disease and there are four stages to it, which are primary, secondary, latent and tertiary and all of these stages does involve hair loss as symptoms (11).

Syphilis is confusing because of the different stages but tests can be conducted to know which stage and how to treat it.

This illness affects not just the hair scalp but the hair on the body as well might start to fall out and syphilis symptoms have a tendency of not reacting until the late-stage or come and go over time. Here are some of its noticeable symptoms.

  • Decreased appetite
  • Enlarged lymph nodes
  • Muscles ache
  • Poor brain function
  • Weight and hair loss

You should contact your physician immediately.

5. Telogen Effluvium

This is a rare kind of illness that is caused by metabolic or hormonal derangements in which hairs are shifted to the last stage of there cycle (12), telogen effluvium can also be a process in other diseases like  malignancy, lupus, end-stage liver or renal disease, hormonal changes, hypothyroidism (shown), protein and calorie malnutrition, heavy metal toxicity, or iron deficiency.

The major symptom of Telogen effluvium is patchy hair loss and scaring might occur on the scalp, a proper test from physicians is adviced as this is a medical condition might show no other symptoms except hair loss.

6. Polycystic Ovary Syndrome (PCOS)

illness that cause hair loss
Image: Vargasfaceandskin.com

Polycystic ovary syndrome is another imbalance in female and male hormones, It’s the release of excess androgens which can lead to ovarian cysts, weight gain, a higher risk of diabetes, changes in your menstrual period, infertility, as well as hair thinning (13).

Women might experience more hair loss than men on the face and body. Other important symptoms of Polycystic ovary syndrome are;

  • Irregular period or no period at all
  • Weight gain
  • Oily skin or acne
  • Difficulty getting pregnant due to the irregular ovulation or failure to ovulate

7. Severe Flu

This type of illness might cause your hair loss to become noticeable after a month or two after the trauma and the good news is that your hair will grow back that, it is not permanent and with the right treatment during flu, you can keep the hair loss minimal.

Consuming lots of protein during this period will help (14), they are topical creams and oral medications that might help as well.

A severe case of infection can also lead to hair loss but it will grow back eventually with the right treatment and avoiding some chemical formulated shampoos pending the growth stage.

8. Cancer

illnesses that cause hair loss

The treatment after cancer apparently can lead to a severe loss of hair, not all drugs used in the treatment of cancer do lead to hair loss but a lot of them do especially chemotherapy.

Chemotherapy is the type of cancer treatment most likely to cause hair loss (15), although cancer cells are the main focus hair, unfortunately, takes the fall along with the growing cells.

Hair regrowth after chemotherapy usually starts within 1 to 3 months after the therapy has finished.


Both overactive and less reactive illness can cause hair loss but it usually grows back except for alopecia areata and telogen effluvium, alopecia areata might not grow back due to hereditary or to severe and in the case of telogen effluvium, it is known as the resting phase of hair.

Read more on hair loss and hair growth:


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