Levothyroxine is the generic form of the brand-name medication Synthroid. It is used to treat low levels of thyroid hormones, also known as hypothyroidism.

It is recommended that you take the drug first thing in the morning with a full glass of water, about an hour before breakfast. You should avoid food and other medications for an hour after taking levothyroxine, and make sure to take it four hours before or after taking iron supplements, calcium supplements, or antacids. At your doctor’s discretion, you might need to avoid foods that affect the absorption of levothyroxine, including soybeans, walnuts, grapefruit, and high-fiber foods. Common side effects include nausea, weight changes, stomach upset, mood changes, and headaches. Tell your doctor straight away if you have symptoms such as chest pain, changes in heartbeat, uncontrollable shaking, nervousness, anxiety, irritability, sleep difficulties, shortness of breath, or excessive sweating, as these can be a sign of a serious problem. Also, make sure to inform your doctor of all other medications (including over-the-counter drugs and supplements) you are taking in order to prevent drug interactions. This paragraph is only an overview, and it is not intended to replace medical counseling; please consult your pharmacist and/or medical provider for more comprehensive information.