Your thyroid is a butterfly-shaped organ that sits at the base of your neck. It produces hormones that regulate body functions.

When your thyroid gland is underactive (called hypothyroidism), it makes too little hormone. When that occurs, your metabolism slows down, and your thyroid may not function normally.

This process may lead to various symptoms, including weight gain, fatigue, depression, dry skin, brain fog, cold intolerance, muscle cramps, and constipation. In addition, without treatment, a goiter (an enlarged thyroid gland) may develop. Other complications can also develop.

This article explains hypothyroid symptoms, complications, and when to see a healthcare provider.

Frequent Symptoms

The symptoms of hypothyroidism tend to be mild or even unnoticeable when the disease is in the early stages. However, symptoms are more dramatic when it develops rapidly.

Moreover, the symptoms can vary significantly from person to person; no single symptom definitively clinches a hypothyroidism diagnosis. 

For instance, while weight gain is typical in hypothyroidism, many people with an underactive thyroid are of average weight or even thin.

The symptoms of hypothyroidism can be non-specific or attributed to other factors, like stress and aging. Therefore, they are often easily missed.

People (and their healthcare providers) begin to suspect an underactive thyroid gland only by looking at symptoms in their totality. 

Slowing Metabolic Processes

Some of the symptoms of hypothyroidism are the result of a slowed metabolism. These include:

  • Fatigue and sleepiness
  • Slowed movement and speech
  • Intolerance to cold
  • Weight gain
  • Slow heart rate
  • Sluggish reflexes
  • Constipation
  • Shortness of breath when exercising
  • Muscle cramps, stiffness, and weakness

Skin, Hair, and Nail Changes

Skin, hair, and nail changes often occur with hypothyroidism. That’s because decreased blood flow, water retention, and slow processes accompany the condition. These symptoms may include:

  • Pale, cool, and thick or “doughy” skin
  • Dry, brittle hair, and hair loss, especially near the outer edge of the eyebrows
  • Brittle, dull, and thin nails
  • Decreased sweating
  • Swelling of the hands, face, and eyelids (called edema)

“Brain Fog” 

“Brain fog” is another symptom of hypothyroidism. While this is not a medical term, per se, it has become a well-recognized description of a group of cognitive symptoms. Brain fog may involve:

  • Difficulty concentrating
  • Short-term and long-term memory problems
  • Forgetfulness
  • Lack of focus
  • Feeling “spaced out”
  • Confusion
  • Difficulty thinking clearly

Brain fog may occur in hypothyroidism because your brain requires sufficient levels of thyroid hormone to function correctly. 

Psychiatric Problems

Hypothyroidism may also mimic the symptoms of depression. These shared symptoms may include:

  • FatigueSleepinessSlowed speechLack of interest in personal relationships General apathy

Sexual and Reproductive Problems 

For some people with hypothyroidism, their first and perhaps the biggest clue is a history of menstrual and reproductive problems. These may include:

People with hypothyroidism may also feel inexplicably anxious or irritable.

  • Missed or frequent periods
  • Heavy bleeding
  • Recurrent miscarriage
  • Repeated failure to conceive
  • Failed assisted reproduction treatments

In addition, as many as half of those with testicles and hypothyroidism experience decreased libido, erectile dysfunction, and delayed ejaculation.

Rare Symptoms

In a person with severe hypothyroidism, a myxedema crisis (also called myxedema coma) may occur. This life-threatening condition results from untreated hypothyroidism. It happens when thyroid hormone levels are extremely low. Symptoms include:

Recap

While hypothyroidism doesn’t always have apparent, identifiable symptoms, there are some common signs that you may want to have your thyroid evaluated. These include fatigue, weight gain, skin, hair, and nail problems, “brain fog,” mood problems, and sexual and reproductive difficulties.

  • Low body temperatureSlowed breathingLow blood pressureLow blood sugarUnresponsivenessUnusual moods

Hypothyroidism in Children

Hypothyroidism in children can either be congenital (meaning you are born with it) or acquired (caused by another condition).

Congenital Hypothyroidism

The most common cause of congenital hypothyroidism is thyroid dysgenesis. The thyroid gland is either missing, malformed, or severely underdeveloped in this condition.

Most newborns with congenital hypothyroidism will have no signs of the disease. However, some may exhibit symptoms such as:

  • LethargyPoor feedingConstipationHoarse cry

Another telltale sign is prolonged jaundice. This condition is when the yellowish color of a newborn’s skin, seen in around 50% of full-term babies, persists for longer than two weeks.

Acquired Hypothyroidism

Hashimoto’s disease, iodine deficiency, or radiation treatment may cause acquired hypothyroidism.

Hashimoto’s disease (also known as Hashimoto’s thyroiditis) is, by far, the most common cause of hypothyroidism in children. It is an autoimmune disorder in which the immune system malfunctions and attacks healthy thyroid tissue.

One of the characteristic signs is the swelling of the neck caused by the enlargement of the thyroid gland. Other symptoms of hypothyroidism in children include:

Kids most at risk for developing acquired hypothyroidism include those with Down syndrome, type 1 diabetes, and children who have received radiation treatment.

  • Cold intoleranceConstipationDelayed puberty (often the first noticeable sign in the teen years)FatigueHair lossMenstrual irregularitiesRough, dry skinSlow growthWeight gain or slow to gain weight

Complications

Several medical conditions may occur due to hypothyroidism, especially when untreated or uncontrolled. 

Hypothyroidism can also occur in children. These cases are either congenital (present at birth) or acquired. Jaundice, poor feeding, and lethargy may be indicators of congenital hypothyroidism in newborns. Hashimoto’s disease is the most common cause of acquired hypothyroidism in kids.

Goiter

A goiter can range from slight enlargement, which may have no other symptoms, to a substantial increase in size.

If you have a large goiter, you may feel swelling or general discomfort in the neck area. In addition, scarves or ties may feel uncomfortable due to neck enlargement. In some cases, your neck and throat may be sore or tender.

Less commonly, swallowing or even breathing can become difficult. That’s because sometimes a goiter can block your windpipe or esophagus.

Peripheral Neuropathy

Hypothyroidism is known to cause peripheral neuropathy. This condition results when the peripheral nervous system (the network of nerves that extend from the brain and spinal cord) is damaged.

It can cause a wide range of symptoms, depending on which nerves are damaged. It often results in localized sensations and pain such as:

  • NumbnessBurning, tingling, or a “pins-and-needles” sensationMuscle weaknessHypersensitivity to touch or temperature

The association between thyroid function and peripheral neuropathy isn’t fully understood. However, researchers believe that hypothyroidism leads to fluid retention, resulting in swollen tissues.

Symptoms of carpal tunnel syndrome may begin with burning and tingling in the palm and fingers, especially the thumb, index finger, and middle finger.

Carpal Tunnel Syndrome

One of the areas commonly affected by this fluid retention is the wrist, where nerves travel through a channel of soft tissue known as the carpal tunnel. When excess fluid causes pressure in this area, it can result in carpal tunnel syndrome. 

This discomfort is often worse at night, especially if you sleep with your wrists bent. In addition, if carpal tunnel progresses, hand muscles may waste away, leading to weakness, particularly decreased grip strength. 

Anemia

A deficiency of thyroid hormone reduces your body’s production of red blood cells in your bone marrow, the spongy tissue that lies in the center of certain bones. Reduced red blood cells can lead to anemia.

Anemia can cause symptoms like:

Anemia

Anemia is a condition where red blood cell count is lower than normal.

  • Fatigue and weaknessPalenessFast or irregular heartbeatsFeeling faintShortness of breath

High Cholesterol

When the thyroid gland produces too little hormone, it can affect your body’s ability to process cholesterol, leading to elevated total cholesterol and LDL levels.

Besides high cholesterol, other heart-related complications associated with hypothyroidism include high blood pressure and fluid around the heart (pericardial effusion). 

LDL cholesterol can build up in your arteries, eventually contributing to blockages that can cause a heart attack or stroke.

Myopathy

Myopathy (or muscle disease) may result from an underactive thyroid gland. People with hypothyroidism-induced myopathy often complain of muscle pain and stiffness. In addition, they may experience muscle weakness that can make simple activities like rising from a chair, climbing stairs, or washing hair difficult.

Infertility and Pregnancy Problems

Untreated hypothyroidism can lead to menstrual irregularities, which can lead to infertility. In addition, research suggests that hypothyroidism during pregnancy increases the risk for pregnancy loss, placental abruption, preterm delivery, and neonatal death. 

When to See a Healthcare Provider

If you are worried that you or a loved one is experiencing one or more symptoms of hypothyroidism, call your healthcare provider for an appointment. In addition to a medical history and physical examination, they can perform a blood test called the thyroid-stimulating hormone (TSH) test, which can narrow down if there is a thyroid problem.

Untreated or uncontrolled hypothyroidism can lead to other medical conditions. These include goiter, peripheral neuropathy, anemia, high cholesterol, myopathy, and fertility and pregnancy problems.

Lastly, if you are pregnant or considering pregnancy and taking thyroid hormone replacement medication, be sure to work with a healthcare provider. Discussing your situation with a doctor will ensure that your thyroid hormone level is at the correct level for the health of both you and your baby. 

Seek medical attention right away if you are experiencing symptoms of myxedema coma, such as severe fatigue or extreme cold intolerance.

Summary

Hypothyroidism is a condition where the thyroid produces too little thyroid hormone. Symptoms commonly include fatigue, weight gain, “brain fog,” and mood problems. Rarely, a condition called myxedema coma can occur when thyroid levels fall to dangerously low levels. Hypothyroidism can lead to other medical conditions, so getting timely diagnosis and treatment is important.

Frequently Asked Questions

  • What is the first sign of Hashimoto disease?
  • For many people, a goiter is commonly the first sign of Hashimoto disease. Other symptoms such as fatigue or weight gain may appear before the goiter, but people might dismiss them as related to aging or stress.
  • Learn More:
  • Symptoms of Hashimoto’s Disease
  • How serious is an underactive thyroid?
  • If left untreated, hypothyroidism could lead to very serious complications. These include heart disease and a rare, life-threatening condition known as myxedema, in which the skin thickens and swells, especially around your face and legs.
  • Learn More:
  • What Is Myxedema Coma?
  • What is a Hashimoto flare-up?
  • A flare-up is when you feel hypothyroidism symptoms. These flare-ups can occur even if you’re on daily hormone replacement therapy. For instance, you might feel unusual fatigue, aches, sensitivity to cold, or memory problems. In addition, stress, diet, and certain medications may cause these flare-ups.
  • Learn More:
  • Hashimoto’s Flare-Up

For many people, a goiter is commonly the first sign of Hashimoto disease. Other symptoms such as fatigue or weight gain may appear before the goiter, but people might dismiss them as related to aging or stress.

If left untreated, hypothyroidism could lead to very serious complications. These include heart disease and a rare, life-threatening condition known as myxedema, in which the skin thickens and swells, especially around your face and legs.

A flare-up is when you feel hypothyroidism symptoms. These flare-ups can occur even if you’re on daily hormone replacement therapy. For instance, you might feel unusual fatigue, aches, sensitivity to cold, or memory problems. In addition, stress, diet, and certain medications may cause these flare-ups.