Common symptoms
Fatigue
Persistent, unexplained tiredness even after a full night of sleep
Weight gain
Unexplained weight gain or difficulty losing weight despite normal eating habits
Cold intolerance
Feeling unusually cold, especially in the hands and feet
Constipation
Slow digestion leading to infrequent or difficult bowel movements
Dry skin or hair
Skin becomes dry and rough; hair may become brittle and fall out
Depression
Low mood, emotional blunting, or difficulty concentrating
Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone to meet the body's needs. This slows down many of the body's functions. The most common cause is Hashimoto's thyroiditis, an autoimmune condition.
Hypothyroidism is a chronic condition without acute attacks in most cases. However, myxedema coma — a rare, life-threatening complication of severe untreated hypothyroidism — requires emergency hospital care.
With consistent levothyroxine treatment, most symptoms gradually improve over 6 to 12 weeks. TSH levels should be rechecked 6 to 8 weeks after starting or adjusting medication to confirm the dose is correct.