Thayoflo is a levothyroxine medication used to treat hypothyroidism. Hypothyroidism occurs when the thyroid gland does not produce enough hormones, leading to fatigue, weight gain, and other symptoms. Levothyroxine replaces thyroid hormone and is taken orally. It is absorbed variably and has a long half-life, requiring careful dosage titration to avoid under or overtreatment. Common side effects of excessive dosage include increased heart rate, insomnia, and diarrhea. Thayoflo should be taken on an empty stomach and with caution during pregnancy and breastfeeding.