Because the onset of hypothyroidism is gradual, its early symptoms are atypical. Specific symptoms only appear when there is a decrease in basal metabolic rate and a reduction in sympathetic nerve excitability. Generally, symptoms include cold intolerance, fatigue, swelling of hands and feet, drowsiness, memory decline, reduced sweating, joint pain, weight gain, constipation, and menstrual irregularities such as heavy or light periods, or infertility in women of childbearing age. Additionally, some common clinical signs include expressionless face, slow response, hoarse voice, hearing impairment, pale complexion, edema around the eyelids, face and lower limbs, thick tongue coating often with teeth marks. Moreover, there are also associated symptoms such as dry skin, flaky skin, low skin temperature, and the hands and feet turning a yellowish-orange color.