Levothyroxine is a synthetic prescription hormone used to treat an underactive thyroid (hypothyroidism) by replacing the natural thyroid hormone T4 the body lacks.
It restores normal metabolism and reverses symptoms like fatigue, weight gain, and cold sensitivity.
Goiter and Thyroid Cancer: Helps shrink enlarged thyroid glands and is used alongside surgery or radioiodine to manage certain thyroid cancers.
It acts as a synthetic version of the T4 hormone, which the body converts into the active T3 hormone.
It is taken once a day on an empty stomach, usually 30 to 60 minutes before breakfast or your first caffeinated drink.
Avoid taking calcium, iron supplements, antacids, or proton pump inhibitors within 4 hours of the dose, as they block absorption.
Common Side Effects
Excess dose signs: Fast heartbeat, tremors, weight loss, and heat sensitivity.
Other effects: Hair loss, skin rash, or changes in menstrual periods when adjusting to the correct dosage.
Long-term risk: High doses over many years can reduce bone mineral density, raising the risk of osteoporosis.