Can the Thyroid Cause Hirsutism?

The thyroid gland is a small piece of tissue located just below the Adam’s apple in the neck. Unbeknownst to most people, the gland is quite active and oversees many bodily functions that we take for granted. The thyroid helps to regulate our body temperature, controls the rate metabolism and propels growth and development of the body. On a daily basis the thyroid gland is constantly releasing a steady amount of thyroid hormones into the bloodstream. These hormones are known as Triiodothyronine and Thyroxine.

But can the thyroid cause excess body hair, also known as Hirsutism?

The Thyroid and Hirsutism 

The thyroid is not directly responsible for excessive hair growth. Instead, only an indirect relationship between the thyroid gland and hirsutism exists.

As all hormonal systems in the body are connected, an imbalance of the thyroid hormones might be related to hirsutism. An under-active thyroid can also lead to hair loss.

Excess Hair Growth and an Underactive Thyroid

The relationship between hirsutism and the thyroid gland is still not fully understood or confirmed that there is any. Different theories have been put forth about the mechanics between these two factors. But whatever the cause, if hirsutism is noticed alongside any of the symptoms of an underactive thyroid, it is quite possible that there might be a problem with the thyroid function. Symptoms of an underactive thyroid are:

  • Fatigue
  • Increased sensitivity to cold
  • Constipation
  • Weight gain
  • Puffy skin

If you experience any of these symptoms and hirsutism, make sure to discuss them with your doctor.

Other Ways the Thyroid Can impact Hair Growth

The thyroid can also impact hair growth in two separate ways:

1 – Polycystic ovary syndrome (PCOS) 

Studies have shown that there may be a link between Polycystic ovary syndrome (PCOS) and certain thyroid diseases. While the level of evidence is still weak, PCOS and the thyroid share a common relationship. So it is important to look out for symptoms of PCOS as well, such as:

  • Irregular period or no periods at all
  • Infertility or difficulty getting pregnant
  • Thinning hair and hair loss from the head
  • Weight Gain or Obesity
  • Oily skin or acne
  • Anxiety or Depression

If you experience some of the symptoms above, make sure to mention them to your doctor as well.

2 – Hypertrichosis

Hypertrichosis is a medical condition of excessive hair growth over and above the normal amount. In contrast to hirsutism, which is excess hair growth in women following a male distribution pattern, hypertrichosis can develop all over the body. It can also be isolated to small patches. Hair growth between the eyes, on the forehead or cheeks is characteristic of hypertrichosis which can be caused by thyroid problems. However, this diagnosis is quite rare.

Hair Loss and an Underactive Thyroid 

The thyroid gland is said to exist in one of three states: Hypothyroid (when the gland is underactive), hyperthyroid (when the gland is overactive) or euthyroid, when the gland is just perfect and is neither secreting too much nor too little thyroid hormone. 

When the thyroid gland becomes underactive, it slows down bodily functions which includes a reduction in hair growth. In some women this is seen as sparse, balding or brittle hair, particularly on the head.

Alongside hair loss, if any of the above symptoms of an underactive thyroid are present then this should be discussed with your doctor. 


To diagnose hirsutism, the doctor will first need to take a detailed medical history and carry out a physical examination. You may be asked about other symptoms apart from excess hair growth. Such as:

  • Symptoms of hypothyroidism like weight gain, fatigue unexplained constipation
  • Symptoms of hyperthyroidism like weight loss, chest palpitations or a feeling of always being hot
  • Symptoms of PCOS like an irregular period, acne or problems getting pregnant

You may also be asked about:

  • Past medical history
  • Medication history (or any supplements you have been taking)
  • Family history (hirsutism may be due to genetics)

Following this, a number of imaging tests including a blood test and ultrasound scan or MRI may be carried out. With these tests results and a comprehensive overview of your medical history, your doctor can then make a diagnosis and discuss treatment options with you.


Treatment of hirsutism should first be centered on treating the underlying cause. If the diagnosis points to an underactive or overactive thyroid, then appropriate medication or surgical options will be discussed with your doctor. Treating the primary cause should result in symptoms such as hirsutism.   

However, if additional methods are needed to remove or reduce unwanted hair growth, then one or more of the of the following techniques can be used.

Physical treatments – such as shaving, waxing or plucking. These are relatively cheap options that offer immediate results but hair regrows within a short period of time. Side effects include irritation of the skin, folliculitis and redness.

Face creams- like Vaniqa are applied directly to the face. Results are usually seen after a few weeks of routine treatment. Once Vaniqa stopped, hair growth will revert. 

Electrolysis –this is considered the only permanent way to remove hair. However, because it is dependent on the skill of the electrologist, results may vary. A fine needle is inserted near the base of the hair shaft where heat or an electrical current is applied. This allows the hair to be removed. The technique is repeated over the course of a few sessions before permanent hair removal will be seen.

Laser treatments/IPL– are popular hair removal techniques. Lasers are used to destroy the hair follicle at the source. Their ease of use, long term results and good side effect profile have given these techniques widespread acceptance 


An underactive thyroid is just one of many different possible conditions that might be behind the development of hirsutism. A complete diagnostic workup by the doctor should be able to find out if a problematic thyroid is the cause, and together you can discuss the best treatment options for you.

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