Can Thyroid Cause Hair Loss?
Thyroid disorders, such as hypothyroidism and hyperthyroidism, can disrupt the hair growth cycle, causing thinning and hair loss. Learn about the causes, mechanisms, symptoms, and treatment options to manage thyroid-related hair loss effectively.
Written by Dr Shreya Sarkar
Last updated on 3rd Jul, 2025
The thyroid is a butterfly-shaped endocrine gland in the neck that regulates metabolism, energy production, and growth. This process is achieved through the secretion of thyroid hormones, principally triiodothyronine (T3) and thyroxine (T4).
There are three phases in the hair growth cycle: the anagen (growth) phase, the catagen (transition) phase, and the telogen (resting) phase. The health of hair follicles alternates seamlessly between these phases, and hair densities are maintained. Hormonal imbalances can cause a disrupted cycle of hair shedding or thinning.
This article explains the correlation between thyroid disorders and hair loss. It highlights the causes, symptoms, mechanisms, diagnosis, and treatment options available to manage and prevent hair loss as much as possible.
Thyroid Disorders Linked to Hair Loss
Severe or prolonged cases of hypothyroidism or hyperthyroidism can lead to hair loss by affecting the entire scalp. However, there are chances of hair regrowth through treating the thyroid disorder, which may take several months. Transient or mild thyroid dysfunction rarely leads to significant hair loss.
Relation between Hypothyroidism and Hair Loss
Hypothyroidism occurs when the thyroid gland produces insufficient thyroid hormones. This deficiency slows down metabolic processes as needed for hair follicle health. People with hypothyroidism frequently have thinning hair or diffuse hair loss on the scalp.
Relation between Hyperthyroidism and Hair Loss
Hyperthyroidism, characterised by excess thyroid hormone production, can also contribute to hair loss. It accelerates the hair growth cycle, causing hair to transition too quickly into the shedding phase. This leads to noticeable thinning, especially if the condition persists untreated.
Mechanism of Hair Loss in Thyroid Disorders
Thyroid hormones are responsible for controlling the production of keratin, the building block of hair strength and growth. An imbalance in thyroid hormones weakens the hair shaft.
Disruption in Hair Growth Cycle Due to Thyroid Imbalance
Hypothyroidism disrupts skin cell division, pushing hair follicles into the catagen phase and delaying their return to the anagen phase. Excess reactive oxygen species (ROS) can cause oxidative damage. Hair shedding may begin months before other symptoms and is reversible with thyroid replacement therapy except in more prolonged cases of follicular atrophy.
Thyroid imbalances can disrupt the hair growth cycle, shortening the anagen and prolonging the telogen. As a result, the hair starts falling out and replacing it at a slower rate, causing the hair to appear thin. Both hypothyroidism and hyperthyroidism exacerbate this imbalance.
Symptoms of Hair Loss Due to Thyroid Issues
Thyroid disorders, including both hypothyroidism and hyperthyroidism, can significantly affect the skin, leading to dryness, thinning, or brittleness due to hormonal imbalances that disrupt metabolism and blood flow. These hormonal fluctuations often result in hair thinning or diffuse hair loss, interfering with the normal hair growth cycle.
Patterns of Hair Loss Associated with Thyroid Dysfunction
- Hair loss due to thyroid disorders usually shows an even, diffuse thinning of hair with hair shedding evenly over the scalp.
- Autoimmune thyroid conditions like Hashimoto's thyroiditis may sometimes present patchy hair loss.
Hair volume and density reduce significantly. - Dry, brittle hair that's more prone to breaking could be noticed.
Other Symptoms Indicating Thyroid-Related Hair Loss
Hair loss caused by thyroid disorders often includes other symptoms, such as fatigue, unexplained weight gain or loss, and changes in the heart rate. Skin changes include dryness in hypothyroidism, increased sweating in hyperthyroidism, brittle nails, and cold intolerance in hypothyroid conditions.
Diagnosis of Thyroid-Related Hair Loss
A physical examination of the scalp and hair is done to examine hair loss patterns and rule out abnormal findings. Knowing the detailed history can discover any underlying thyroid dysfunction.
Thyroid Function Tests
Certain thyroid function tests, such as TSH (thyroid-stimulating hormone) and T4 (thyroxine), are the most reliable methods to diagnose thyroid-related hair loss, complemented with a thorough clinical evaluation.
A blood test measuring thyroid hormone levels is the most reliable method for determining thyroid hormone-related hair loss. A physical examination and a patient’s medical history review may be required for further diagnostic measures.
Key thyroid function tests include:
- TSH: High or low thyroid stimulating hormone levels are strong indications of thyroid disease.
- T4: The measure of T4 levels is essential for evaluating thyroid function and confirming diagnosis.
Treatment Options for Hair Loss Caused by Thyroid Disorders
Here are some treatment approaches to improve hair health affected by thyroid disorders:
Medication to Restore Thyroid Balance
Restoring thyroid hormone balance is the first step in responding to thyroid-related hair loss. Levothyroxine is a synthetic thyroid hormone replacement for hypothyroidism. Treatment for hyperthyroidism consists of taking anti-thyroid medications or radioactive iodine to balance the hormones.
Hair Loss-Specific Treatments
Options such as minoxidil (topical solution promoting hair regrowth) or dietary supplements can reinforce hair growth. Increasing the biological synthesis of iron and biotin can further improve hair health.
Managing and Preventing Hair Loss with Thyroid Conditions
Stress enhances premature follicles involved with hair loss. Meditation, yoga, or exercise can be stress management techniques to combat hair loss as they aid in managing cortisol levels. Here are more considerations:
- Gentle Hair Handling: Avoid tight hairstyles and cosmetic products on fragile hair.
- Appropriate Hair Care: Gently wash or style your hair, and use dermatologist-approved products.
- Dietary Considerations: Have a well-balanced diet with calcium-rich foods and take calcium supplements only if advised by a doctor. Ensure that calcium supplements are not taken within four hours of levothyroxine or iodine-containing products.
Potential Complications of Untreated Thyroid-Induced Hair Loss
Coarse, dry, and fragile hair is a common symptom of hypothyroidism, contributing to widespread hair thinning. In contrast, hyperthyroidism accelerates hair loss due to an increased metabolic rate.
Persistent thyroid imbalances can cause hair to shed excessively, with more hair entering the resting (telogen) phase of the hair growth cycle, resulting in noticeable thinning across the scalp.
Untreated thyroid-induced hair loss can cause embarrassment, self-consciousness, and social withdrawal. Noticeable changes in appearance occur in men, causing decreased confidence and increased anxiety, which can sometimes lead to depression and anxiety disorders.
Conclusion
Thyroid disorders can significantly impact hair health, leading to thinning, brittleness, or hair loss. Early diagnosis and treatment are crucial to restoring hormonal balance and supporting hair regrowth. Adopting appropriate hair care practices, stress management, and a balanced diet can further enhance hair health. Consult a healthcare professional for a personalized treatment plan to manage thyroid-related hair loss effectively.
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