Hypothyroidism Symptoms: Early Signs, Causes & Diagnosis

Quick Glance: Common Hypothyroidism Symptoms

Common symptoms of hypothyroidism include:

Persistent tiredness
Increased sensitivity to cold
Gradual weight gain
Constipation
Dry skin
Dry or thinning hair
Difficulty concentrating or thinking clearly
Low mood

Symptoms usually develop gradually and may not be easy to notice in the early stages.

Hypothyroidism Symptoms That Should Not Be Ignored

Some symptoms of hypothyroidism are common and may have other causes. However, persistent or worsening symptoms, particularly when several occur together, should be assessed by a doctor. Check out the symptoms of hypothyroidism that should not be ignored:

Symptom or Change	What It May Indicate
Noticeably slow heart rate	An effect of low thyroid hormone levels on heart function
Increasing muscle weakness or persistent muscle aches	Effects of thyroid hormone deficiency on muscle function
Heavy or increasingly irregular periods	Thyroid-related disruption of menstrual function
Difficulty getting pregnant	Possible effect of thyroid dysfunction on fertility
Swelling or enlargement at the front of the neck	An enlarged thyroid gland, or goitre, that needs assessment
Several hypothyroidism symptoms developing together	A pattern that may warrant thyroid function testing
Symptoms that persist or increasingly affect daily activities	Hypothyroidism or another condition requiring medical assessment

Hypothyroidism can affect the heart, muscles, reproductive system and other body functions. However, these symptoms do not confirm hypothyroidism because they can occur with other conditions as well.

Why Do Hypothyroidism Symptoms Occur?

Hypothyroidism occurs when thyroid hormone levels in the body are too low. The thyroid gland in the neck produces the hormones thyroxine (T4) and triiodothyronine (T3), which regulate how the body uses energy and influence functions such as heart rate, body temperature, digestion, muscle activity and brain function.

When thyroid hormone levels are too low, several body processes slow down. This can contribute to tiredness, increased sensitivity to cold and slower digestion, which may lead to constipation.

Low thyroid hormone levels can also affect tissues that regularly renew themselves. This may contribute to dry skin, thinning hair and other changes affecting the skin and hair.

The heart, muscles and nervous system can also be affected. Some people may experience a slower heart rate, muscle weakness, aches, low mood or difficulty concentrating. In women, hypothyroidism can also affect menstrual function and fertility.

The pituitary gland helps regulate thyroid activity by producing thyroid-stimulating hormone (TSH). When thyroid hormone levels fall because of a problem with the thyroid gland, TSH levels usually rise to encourage the thyroid to produce more hormone.

Hypothyroidism Symptoms That Require Immediate Medical Attention

Hypothyroidism usually develops gradually and does not normally cause a sudden medical emergency. However, seek emergency medical care for:

Severe confusion or reduced responsiveness
Extreme drowsiness or difficulty waking
Loss of consciousness
Very slow or shallow breathing
Abnormally low body temperature
Very low blood pressure
Severe weakness or collapse

These symptoms can indicate that essential bodily functions are slowing dangerously and require immediate hospital treatment.

Symptoms of Hypothyroidism Based on Type

The table below presents the symptoms of hypothyroidism based on type:

Type	Common Symptom Pattern
Primary hypothyroidism	Tiredness, cold intolerance, constipation, gradual weight gain, dry skin, hair changes, muscle symptoms and low mood
Central hypothyroidism	Symptoms such as tiredness, cold intolerance, constipation, weight changes and difficulty concentrating; other symptoms may relate to an underlying pituitary or hypothalamic disorder
Subclinical hypothyroidism	Often causes no noticeable symptoms; some people may experience mild or non-specific symptoms such as tiredness

Symptoms of Hypothyroidism-Specific Conditions

The common symptoms of hypothyroidism-specific conditions are presented in the table below:

Condition	Common Symptom Pattern
Hashimoto's Disease	Persistent tiredness, increased sensitivity to cold, constipation, gradual weight gain, dry skin or thinning hair, muscle aches or weakness, difficulty concentrating, and an enlarged thyroid gland in some people
Postpartum Thyroiditis	Tiredness, increased sensitivity to cold, dry skin, difficulty concentrating, low mood, constipation

Symptoms of Hypothyroidism in Women

Women can experience the usual symptoms of hypothyroidism, such as tiredness, cold intolerance, constipation, weight gain, dry skin and difficulty concentrating. In addition, thyroid dysfunction can affect menstrual and reproductive health.

Symptoms of hypothyroidism in women may include:

Heavy or irregular periods
Difficulty getting pregnant
Reduced fertility
Hypothyroidism symptoms during or after pregnancy

During pregnancy, symptoms such as tiredness, constipation, cold intolerance and difficulty concentrating can overlap with normal pregnancy changes. If these symptoms are persistent or concerning, a doctor may recommend thyroid function testing.

Symptoms of Hypothyroidism in Children

Hypothyroidism can affect growth and development in children. Slowed height growth is an important sign, while delayed puberty can occur in adolescents.

Other symptoms of hypothyroidism in children and teenagers include:

Persistent tiredness
Constipation
Increased sensitivity to cold
Dry skin
Dry or brittle hair
Low mood
Weight gain
An enlarged thyroid gland
Heavy or irregular periods in adolescent girls

A baby born with congenital hypothyroidism may have few or no obvious symptoms at first. Newborn screening helps identify the condition early, before prolonged thyroid hormone deficiency affects growth and development.

Can You Have Hypothyroidism Without Symptoms?

Yes. Hypothyroidism can develop gradually, so some people have few or no noticeable symptoms, particularly in the early stages. Changes such as tiredness, weight gain or feeling cold may also be mistaken for stress, ageing or everyday fatigue.

Subclinical hypothyroidism may cause no obvious symptoms or only mild, non-specific symptoms. Blood tests can show an abnormal TSH level while the free T4 test remains within the usual reference range. Doctors interpret these results alongside symptoms and other clinical factors to determine a diagnosis.

When Can Hypothyroidism Symptoms Become Life-Threatening?

Severe untreated hypothyroidism can rarely progress to myxoedema coma, in which essential body functions become dangerously slowed. Here is why it can be dangerous:

Emergency Condition	Why It Is Serious
Myxoedema coma	Severe thyroid hormone deficiency can cause dangerously low body temperature, slowed breathing, low blood pressure and reduced consciousness. It requires immediate hospital treatment.

Myxoedema coma is rare but is a medical emergency requiring immediate treatment.

How are Hypothyroidism Symptoms Diagnosed?

Symptoms alone cannot confirm hypothyroidism because many of them can occur with other conditions. Doctors assess the symptoms, medical history and physical findings alongside thyroid function tests to confirm a diagnosis. Take a look at the diagnostic tests used to detect hypothyroidism:

Diagnostic Test or Assessment	Purpose
Symptom and medical history	Reviews the type, duration and progression of symptoms and relevant medical factors
Physical examination	Checks for features such as thyroid enlargement, changes in heart rate and other physical signs
TSH blood test	Measures thyroid-stimulating hormone and is commonly used as the initial thyroid function test when primary thyroid disease is suspected
Free T4 (FT4) test	Measures available thyroxine and helps assess thyroid hormone status
Thyroid peroxidase antibody (TPOAb) test	Helps determine whether autoimmune thyroid disease may be contributing to hypothyroidism

For suspected primary hypothyroidism, TSH is commonly assessed first, with FT4 measured when appropriate. If a pituitary or hypothalamic disorder is suspected, TSH and FT4 are assessed together because TSH alone may not provide a complete picture.

FAQs

Q1. What are the first symptoms of hypothyroidism?

Ans: Early symptoms often include persistent tiredness, feeling colder than usual, constipation, dry skin and difficulty concentrating. These changes usually build up slowly over weeks or months instead of appearing all at once.
Q2. Does hypothyroidism always cause weight gain?

Ans: No. Weight gain is a recognised symptom, but it does not affect everyone and is not specific to hypothyroidism. Thyroid blood tests are needed to find out whether low thyroid hormone levels are contributing to a change in weight.
Q3. Can hypothyroidism cause brain fog?

Ans: Hypothyroidism can cause difficulty concentrating or thinking clearly, often described as brain fog. Since several other conditions can produce the same effect, ongoing concentration problems are worth getting checked.
Q4. Can hypothyroidism cause hair loss?

Ans: Yes. Dry or thinning hair and increased hair loss are recognised hypothyroidism symptoms. They can develop gradually alongside other changes such as fatigue, dry skin or increased sensitivity to cold.
Q5. Does hypothyroidism affect periods?

Ans: Yes. Heavy or irregular periods and fertility problems can occur in some women with hypothyroidism. A doctor should assess any menstrual changes that show up together with other thyroid symptoms.
Q6. Can hypothyroidism develop without noticeable symptoms?

Ans: Yes. Mild or subclinical hypothyroidism can produce few or no noticeable symptoms. Some people first learn that their thyroid function is abnormal after having a blood test.
Q7. What are the important hypothyroidism symptoms in children?

Ans: Slowed height growth and delayed puberty are particularly important symptoms of hypothyroidism in children and adolescents. Tiredness, constipation, cold intolerance, dry skin, hair changes and an enlarged thyroid gland can also occur.
Q8. Which hypothyroidism symptoms require emergency care?

Ans: Severe confusion, extreme drowsiness, loss of consciousness, very slow breathing, very low blood pressure or an abnormally low body temperature are hypothyroidism symptoms that require emergency medical attention. These signs can occur with myxoedema crisis, a rare but life-threatening complication of severe hypothyroidism.