Articles

Evidence based

Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

How Do Thyroid and Hair Loss Relate?

Written by Dr. Michael Ruscio, DC on December 26, 2022

Written by Dr. Michael Ruscio, DC on December 26, 2022 — Reviewed by Dr. Hannah Hamlin

There’s no doubt that thyroid issues can lead to hair loss, but there’s more to it than that.

• Thyroid and Hair Loss: What’s the Connection?|
• What Are Other Potential Causes of Hair Loss?|
• Treating Hair Loss|
• Getting at the “Root” of Thyroid and Hair Loss|

Unexplained hair loss can feel stressful and frustrating. For most of us, hair holds cultural and social meaning and value, and it can be a big part of our identities. So it’s understandably distressing if you’re seeing your shower drain getting clogged with more and more hair.

Hair loss can result from a number of potential factors, including a thyroid condition (hyper- or hypothyroidism). But poor thyroid function is only one of many potential culprits for hair loss. If you’re wondering if your thyroid is at the root of your hair loss, it’s easy enough to test your levels, but unless you’re experiencing a number of other symptoms of thyroid dysfunction, there’s a good chance something else is going on [1, 2, 3, 4].

Once you’ve tested, your results will help you determine what to do next. If your over- or underactive thyroid is, in fact, the problem, treating the thyroid directly is the first big step. If you find that your thyroid levels aren’t to blame for your hair loss, I’ll explain some other possibilities and ways to help stimulate hair growth.

Thyroid and Hair Loss: What’s the Connection?

Both hypothyroidism and hyperthyroidism can cause hair loss, especially if it’s severe and has gone untreated. Thyroid-related hair loss doesn’t look like pattern baldness where the hair recedes or a bald spot develops. Instead, the hair loss is diffused across the entire scalp and looks like general thinning hair. Once severe thyroid dysfunction is treated successfully, most, if not all, of your hair will grow back over time.

Several studies have linked thyroid problems with hair loss. One observational study found that androgenic alopecia—male pattern baldness, the most common type of hair loss— was linked to hypothyroidism in 12% of the women studied [1]. Other studies link various types of alopecia (the umbrella term for hair loss, regardless of cause), to thyroid dysfunction in between 12% and 42% of cases [2, 3, 4].

The research seems to show that hair loss is more common in those with an overactive thyroid than those with an underactive one, but that both types of thyroid dysfunction can lead to greater occurrences of hair loss than the controls studied [5, 6]. That being said, those experiencing subclinical levels of hypothyroid showed the same amount of hair loss (and all other thyroid symptoms) as the control groups in a 2021 observational study [7]. In other words, it’s unlikely that a subclinical hypothyroid is to blame for hair loss.

It’s also important to restate that even though hair loss is a common symptom of thyroid conditions, we sometimes jump to thyroid dysfunction too quickly as being the cause. Hair loss in and of itself doesn’t always indicate a thyroid problem, and focusing too much on the thyroid can distract from other possible causes.   It’s worth testing your thyroid levels with a simple blood test to find out if your thyroid is to blame for your hair loss, especially if you’re over 40 years of age [4]. If your levels are abnormal, beginning treatment with thyroid medication and/or a thyroid-supportive protocol with a trained healthcare professional is the first step in stimulating new hair growth. I’ll talk more about treatment options at the end of this article.

Thyroid Mechanisms that Can Affect Hair Growth

Understanding the connection between the thyroid gland and healthy hair growth could inform the strategy for hair regrowth if you’re experiencing thyroid problems. Without going too far down the physiology rabbit hole, we know that the thyroid gland produces thyroid hormones, and research has shown that human hair follicles contain detectable levels of thyroid hormone and enzymes that are necessary for the conversion of T4 into T3 [8, 9].

Keratin, the main ingredient in hair itself, is produced by keratinocytes in the hair follicle. An in vitro study found that treating the hair follicle with T4 led to an increase in the number of keratinocytes. The same study also found that T3 and T4 inhibited the death of hair follicle keratinocytes, and prolonged the duration of the growth phase of hair follicles [9]. 

Another in vitro study showed that T3, T4, TSH, and TRH stimulated the production and activity of mitochondria in human hair follicles, which is important because mitochondria are vital for energy production in cells [10].

So we know that thyroid hormones at proper levels play a key role in hair growth. It makes sense that thyroid disease would affect hair growth or trigger hair fall.

Common Symptoms of Hypothyroidism

It’s worth noting that hair loss is typically not a stand-alone symptom of thyroid disorders. In the case of hypothyroidism or Hashimoto’s thyroiditis (the autoimmune disease that can lead to hypothyroidism), you might also see some of the following symptoms:

• Tiredness [11, 12, 13, 14, 15, 16]
• Constipation [11, 12, 13, 14, 15, 16]
• Dry skin [11, 12, 13, 14, 16]
• Cold intolerance [11, 13, 14, 16]
• Weight gain [11, 13, 14, 16]
• Hoarseness [11, 13, 14, 16]
• Mood changes [12, 14, 15]
• Muscle pain [12, 14, 15]

If your hair loss is accompanied by any of these other symptoms, it’s an even greater indicator that you should get your levels checked. The more symptoms you have from this list, the more likely it is that you have hypothyroidism, especially if you have 4 or more [17].

Common Symptoms of Hyperthyroidism

Since hair loss seems to be more common with hyperthyroidism than hypo-, it’s important to look for potential signs and symptoms. Graves’ disease is the autoimmune disease that’s most commonly linked to hyperthyroidism. Here are some things to look out for [18]:

• Weight loss despite a higher appetite
• Heart palpitations
• Nervousness
• Tremors
• Difficulty breathing
• Becoming easily fatigued
• Diarrhea or increased GI motility
• Muscle weakness
• Heat intolerance
• Sweating more than usual
• Irregular menstrual cycles

Another visible symptom to look out for is bulging of the eyes. This physical symptom can not only change your appearance but, in rare cases, can negatively impact your eye health and vision, so don’t ignore the signs.

What Are Other Potential Causes of Hair Loss?

Alopecia is the term used to describe hair loss of any kind, regardless of the cause. This includes the loss of body and facial hair as well as head hair [19]. It can result from a number of factors, some of which do have an impact on your thyroid (and some that don’t).

Genetics

A family history of hair loss has been observed in women and girls ranging from age eight to 86 years of age. Hypothyroidism was shown to be hereditary in 12% of cases, with nearly 85% showing a family history of androgenic alopecia [1]. Androgenic alopecia (male-pattern baldness) affects 85% of men and 40% of women and is likely caused by an excessive response to the male hormone dihydrotestosterone (DHT) [20, 21].

Psychological and Physical Stress

In a study looking at hair loss in women, far more (63.7%) had stress as a common exacerbating factor for their hair loss, while thyroid issues were only present in 17% of cases [22].

On the physical stress front, a 2016 literature review identified some of the major causes of hair loss from published research. The review found that fever, postpartum period, oral contraception, crash dieting, anesthesia exposure, and surgery can all provoke telogen effluvium (hair loss) [6].

Stress can also have a sizable impact on endocrine health, which includes thyroid health. So taking measures to reduce your overall stress (be it emotional or physical) is a good idea, whether your thyroid levels are healthy or not.

Gut Inflammation and Nutrient Deficiency

Along the same lines, gut inflammation and microbial dysbiosis are types of physical stress that can affect nearly every system of the body. This includes thyroid function. Hypothyroid symptoms, such as fatigue, hair loss, dry skin, and weight gain without evidence of low thyroid function on lab tests, can often be linked to inflammation in the gut. Inflammation damages your body’s ability to use thyroid hormone, and this can lead to hypothyroid symptoms [23].

Diet and lifestyle factors such as smoking, eating high amounts of red meat relative to fruits and veggies, excessive alcohol consumption, and sleep issues can all lead to both gut problems and hair loss [20].

Nutrient deficiencies have also been linked to hair loss.  A 2016 literature review found that deficiencies in essential fatty acids, protein, vitamins, zinc, and iron may cause hair loss. Additionally, excess vitamins and selenium were linked to hair loss [6]. Low levels of vitamin D, iron, and zinc have also been associated with hypothyroidism and hair loss in 85% of patients studied, and a vegetarian diet also accounted for 85% of women experiencing hair loss [1, 24].

Illnesses such as autoimmune conditions, infections, and other common chronic diseases, which often have a gut health component, have also been associated with hair loss [6, 20, 25, 26]. Balancing the gut microbiome through a healthy diet and probiotic supplementation is one of the best first steps you can take to address a multitude of symptoms related to thyroid, hair loss, and your overall health and wellness.

Other Potential Factors

Other exogenous reasons for hair loss include:

• Excess selenium, vitamin A, and vitamin E [6, 20]
• Certain common medications like high blood pressure medications, antiarrhythmics, statins, beta-blockers, anti-coagulants, laxatives, antivirals, and psychotropic drugs [6]
• Contaminated supplements [6]
• Toxins such as chemicals from hair dyes, highly processed foods, and heavy metals [6, 22]

These exposures are all important to consider, whether they require small lifestyle tweaks or reevaluating some of your supplements and medications with your doctor.

Treating Hair Loss

Conventional treatment for hair loss typically includes the medications finasteride and topical minoxidil, often in combination [20]. Unfortunately, conventional medications aren’t without side effects, and minoxidil must be taken indefinitely to continue experiencing results. Negative side effects can include sexual dysfunction, contact dermatitis, headache, other body hair increase, and low blood pressure [27].

Low-intensity laser (red light therapy) and hair transplantation are also options [28, 29]. Red light therapy (RLT) does show some promise, but it seems that the improvements are slight, with patient satisfaction being relatively similar to those who were given a sham treatment in the study [30]. This isn’t to say that RLT can’t help, but individual results will vary. Hair transplantation is both invasive and expensive, and although it doesn’t address the root cause, it remains a viable option as a solution for hair loss [29].

Natural Treatments

Natural treatments that have been shown to improve hair loss in human clinical trials outside of RLT include supplementing Vitamin D, iron, biotin*, and probiotics, as well as a number of topical herbal treatments.

Vitamin D and iron deficiencies seem to be consistent across various types of alopecia, so supplementing would make a lot of sense, although more work needs to be done to measure efficacy [31, 32, 33, 34].

*Biotin (a B vitamin) is an ingredient found in hair, but the research seems to show that supplementing it may only be beneficial in cases where it’s poorly absorbed by the gut due to some other underlying pathology [35].

We’ve already discussed how gut health plays a role, so starting a probiotic regimen also makes a lot of sense, although again, more research is needed to draw a direct connection [36].

Herbals applied topically, like garlic gel, pumpkin seed oil, rosemary oil, tea tree oil, and others, as well as saw palmetto taken orally, have also shown promise in natural hair regrowth (32, 37, 38, 39]. Caffeine shampoos, oral and topical capsaicin (a chemical found in hot peppers), collagen, ginseng, and even melatonin have also been studied to aid in natural hair regrowth [32, 39]. Energetic and psychological approaches (which may have a positive effect on stress) like acupuncture, hypnotherapy, psychotherapy, and mindfulness-based therapies have also been studied [32, 39, 40]

As you may have guessed, lifestyle factors to support hair regrowth include reducing stress, eating a healthy, nutrient-dense diet, and maintaining proper hair care, especially by eliminating potential irritants in your body care products [32, 39, 40].

Getting at the “Root” of Thyroid and Hair Loss

Now that you have a better understanding of the relationship between thyroid and hair loss, you can take the steps you need to uncover what could be at the root of your problem. Getting a thyroid test through your healthcare provider is a relatively simple process, but it will help you on the road to understanding your hair loss. Once you’ve found answers there, you’ll have a much better understanding of what the next steps should be.

Treating your thyroid will be essential if your thyroid hormone levels are out of balance, and taking a holistic approach that looks at your diet and lifestyle, stress levels, as well as your gut health is the most thorough way to approach the problem. Let’s work together to address your hair loss. Reach out to our clinic to set up a chat. You may also be interested in taking a look at our Thyroid Course, which will give you some more insight into how to address your thyroid yourself.

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.