Headaches are one of the most common health complaints, affecting millions of people worldwide. While most headaches are caused by tension, stress, or dehydration, there is growing evidence that thyroid disorders — particularly hypothyroidism (low thyroid function) — may be an overlooked cause of chronic headaches and migraines.
If you experience frequent headaches alongside other symptoms such as fatigue, weight gain, or feeling cold, your thyroid may be worth investigating. This article explores the connection between low thyroid function and headaches, helping you understand when thyroid testing might be appropriate.
Understanding the Thyroid and Its Functions
The thyroid is a small, butterfly-shaped gland located at the front of your neck. Despite its modest size, it plays a crucial role in regulating your body's metabolism, energy levels, and numerous physiological processes.
The thyroid produces two main hormones:
These hormones influence virtually every cell in your body, affecting heart rate, body temperature, energy metabolism, brain function, and much more. When thyroid hormone levels are too low (hypothyroidism), many bodily functions slow down, leading to a wide range of symptoms.
The Link Between Low Thyroid and Headaches
Research has increasingly demonstrated a connection between thyroid disorders and headaches. Several studies have found that people with hypothyroidism are more likely to experience headaches than those with normal thyroid function.
How hypothyroidism may cause headaches:
1. Changes in blood vessel function
Thyroid hormones help regulate blood vessel tone and blood flow. Low thyroid levels can affect how blood vessels dilate and constrict, potentially triggering headaches. Some researchers believe this vascular dysregulation is similar to what occurs during migraines.
2. Fluid retention and tissue swelling
Hypothyroidism often causes fluid retention and a condition called myxoedema, where tissues accumulate mucopolysaccharides. This swelling can affect tissues around the brain and may contribute to headache symptoms.
3. Metabolic changes
The brain requires a constant supply of energy to function properly. When thyroid hormones are low, cellular metabolism slows throughout the body, including in the brain. This metabolic disruption may contribute to headaches.
4. Altered neurotransmitter levels
Thyroid hormones influence the production and regulation of neurotransmitters such as serotonin, which plays a key role in both mood and headache regulation. Low serotonin levels are associated with both depression and migraines.
5. Muscle tension
Hypothyroidism can cause muscle stiffness and tension, particularly in the neck and shoulders. Tension in these areas is a well-known trigger for tension-type headaches.
Types of Headaches Associated with Thyroid Disorders
People with hypothyroidism may experience different types of headaches:
Tension-type headaches:
These are the most common type, characterised by a dull, aching pain that feels like a tight band around the head. They may be caused by muscle tension associated with hypothyroidism.
Migraines:
Some research suggests that thyroid disorders may increase migraine frequency or severity. Migraines typically involve throbbing pain, often on one side of the head, and may be accompanied by nausea, vomiting, and sensitivity to light and sound.
New daily persistent headache:
Some individuals with thyroid disorders develop chronic daily headaches that begin suddenly and persist over time.
Other Symptoms of Hypothyroidism
Headaches rarely occur in isolation with hypothyroidism. If your thyroid is underactive, you may also experience:
If you recognise several of these symptoms alongside frequent headaches, thyroid testing is worth considering.
Diagnosing Thyroid-Related Headaches
Determining whether your headaches are related to thyroid dysfunction requires proper testing. The key tests include:
TSH (Thyroid-Stimulating Hormone):
This is usually the first test performed. TSH is produced by the pituitary gland and signals the thyroid to produce hormones. High TSH typically indicates an underactive thyroid, as the pituitary works harder to stimulate hormone production.
Free T4:
Measures the amount of unbound, active T4 hormone in your blood. Low free T4 alongside high TSH confirms hypothyroidism.
Free T3:
Measures the active thyroid hormone. Some people have difficulty converting T4 to T3, so this test provides additional information.
Thyroid antibodies:
Tests for TPO antibodies and thyroglobulin antibodies can identify autoimmune thyroid disease (Hashimoto's thyroiditis), the most common cause of hypothyroidism in the UK.
For comprehensive information about thyroid testing, our guide on thyroid function tests explains what each marker means and how to interpret your results.
Treatment and Management
If hypothyroidism is confirmed as a contributing factor to your headaches, treatment typically involves thyroid hormone replacement therapy:
Levothyroxine:
The standard treatment for hypothyroidism is a synthetic form of T4 called levothyroxine. When taken daily, it restores normal thyroid hormone levels. Many patients report improvement in their headaches once thyroid levels are optimised.
Monitoring and adjustment:
Finding the right dose takes time. Regular blood tests are needed to monitor thyroid levels and adjust medication accordingly. It may take several weeks or months to feel the full benefits of treatment.
Addressing other factors:
While treating thyroid dysfunction may reduce headaches, other contributing factors should also be addressed:
When to Seek Medical Advice
You should consult a healthcare provider if you experience:
Other Health Conditions to Consider
While investigating headaches, it is worth considering other potential causes that blood tests can help identify:
A comprehensive blood test panel can help rule out multiple potential causes. Learn more about the top 10 important blood tests that can provide insights into your overall health.
Thyroid Testing in London
At Private Blood Tests London, we offer comprehensive thyroid function testing at our CQC-registered clinic in South Kensington. Our thyroid panel includes TSH, Free T4, Free T3, and thyroid antibodies, giving you a complete picture of your thyroid health.
If you are experiencing persistent headaches alongside symptoms of thyroid dysfunction, getting tested is a simple first step toward answers. Our experienced healthcare team provides professional service with results delivered quickly and securely.
Explore our [thyroid test page](/thyroid-test) and [comprehensive health screening options](/health-screening).
Take control of your health — book your thyroid function test today.