Medscape - Hypothyroidism-specific dosing for Synthroid, Levoxyl (levothyroxine), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation. Are you on Levothyroxine but still experiencing symptoms of Hypothyroidism? Use this dosage guide to help you find how much you should be taking. Learn how levothyroxine doses are calculated, what tablet strengths are available, and how dosing changes with age, pregnancy, and time. Enter the patient’s body weight (kg or lbs) to calculate the full oral thyroid replacement dose of levothyroxine for the treatment of hypothyroidism. Detailed Levothyroxine dosage information for adults, the elderly and children. Includes dosages for Hypothyroidism, TSH Suppression and Myxedema Coma; plus renal, liver and dialysis adjustments. View SYNTHROID® 12 precise dosing options. Find SYNTHROID® dose calculations, adjustments, guidelines, and food & drug interactions here. Learn about Synthroid (levothyroxine) dosage, including starting doses, dosage charts for adults and children, adjustments, and how to take it safely. Synthroid (levothyroxine) is a prescription drug used to treat hypothyroidism and to suppress TSH. Learn about the drug’s dosages, strengths, and more. Detailed dosage guidelines and administration information for Synthroid (levothyroxine sodium). Includes dose adjustments, warnings and precautions. For most adults, the starting levothyroxine (Levoxyl, Synthroid, Tirosint) dosage will be around 1.6 mcg per kg of body weight. But that can vary based on your age and other health conditions.