What are the symptoms of hypothyroidism (underactive thyroid)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Article Review Status
Submitted
Under Review
Approved

Last updated: April 17, 2025 • View editorial policy

From the Guidelines

Symptoms of hypothyroidism include fatigue, increased sensitivity to cold, constipation, dry skin, unexplained weight gain, puffy face, hoarseness, muscle weakness, elevated blood cholesterol, muscle aches and stiffness, joint pain, irregular or heavy menstrual periods, thinning hair, slowed heart rate, depression, and impaired memory, as noted in a study published in the Journal for ImmunoTherapy of Cancer 1. These symptoms occur because the thyroid gland isn't producing enough thyroid hormones, which regulate metabolism throughout the body. When thyroid hormone levels are low, bodily processes slow down, causing these various symptoms. The severity of symptoms typically correlates with the degree of thyroid hormone deficiency. Some people, especially older adults, may have no symptoms at all or attribute them to aging. If you experience these symptoms, see a doctor for blood tests to check thyroid function. Key symptoms to look out for include:

  • Fatigue
  • Increased sensitivity to cold
  • Constipation
  • Dry skin
  • Unexplained weight gain
  • Puffy face
  • Hoarseness
  • Muscle weakness
  • Elevated blood cholesterol
  • Muscle aches and stiffness
  • Joint pain
  • Irregular or heavy menstrual periods
  • Thinning hair
  • Slowed heart rate
  • Depression
  • Impaired memory Treatment usually involves taking levothyroxine (Synthroid, Levoxyl), a synthetic thyroid hormone, typically starting at 25-50 mcg daily and adjusting based on symptoms and blood tests every 6-8 weeks until optimal levels are reached, as recommended by the U.S. Preventive Services Task Force 2, 3, 4, 5. Most people require lifelong treatment.

From the FDA Drug Label

They include the following: • General:fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating • Central nervous system:headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia • Musculoskeletal:tremors, muscle weakness, muscle spasm • Cardiovascular:palpitations, tachycardia, arrhythmias, increased pulse and blood pressure, heart failure, angina, myocardial infarction, cardiac arrest • Respiratory:dyspnea • Gastrointestinal:diarrhea, vomiting, abdominal cramps, elevations in liver function tests • Dermatologic:hair loss, flushing, rash • Endocrine:decreased bone mineral density • Reproductive:menstrual irregularities, impaired fertility

The symptoms of hypothyroidism are not directly listed in the provided drug label. The label lists symptoms of hyperthyroidism due to therapeutic overdosage of levothyroxine sodium. Key points:

  • The label does not provide information on hypothyroidism symptoms.
  • The provided information is related to hyperthyroidism symptoms. 6

From the Research

Symptoms of Hypothyroidism

The symptoms of hypothyroidism can vary from person to person, but common symptoms include:

  • Fatigue and lethargy 7, 8, 9
  • Cold intolerance 7, 8, 9
  • Weight gain 7, 8, 9
  • Constipation 7, 8, 9
  • Dry skin (xeroderma) 7, 8, 9
  • Voice changes 7, 9
  • Irregular bowel movements 8
  • Decreased metabolic rate, leading to weight gain and cold intolerance 8

Severity of Symptoms

The symptoms of hypothyroidism can range from minimal to life-threatening, with severe cases potentially leading to myxedema coma 7, 9. If left untreated, hypothyroidism can lead to severe complications, such as mental retardation, delayed milestones, heart failure, infertility, and myxedema coma 8.

Diagnosis and Treatment

Diagnosis of hypothyroidism is based on laboratory tests that measure the levels of thyroid hormones (T3 and T4) in the blood 8, 9. Treatment typically involves lifelong hormone replacement therapy with synthetic thyroid hormone replacement medication, such as levothyroxine, to help regulate hormone levels in the body 7, 8, 9.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.