Key takeaways
Unithroid (levothyroxine) and Synthroid (levothyroxine) are both medications used to treat hypothyroidism and certain types of thyroid cancer. They belong to the same medication class as they are both lab-made versions of thyroxine (T4), and they work by replacing or adding to the T4 hormone in your body. Both medications are taken orally once a day, usually on an empty stomach in the morning, and require regular blood tests to ensure the correct dosage. The main difference between Unithroid and Synthroid lies in their inactive ingredients, which are the fillers and binders used to make the tablets. These differences can affect how the medication is absorbed in your body and can possibly affect allergies. Both medications have similar side effects, such as headache, trouble sleeping, and weight loss, which usually occur if the dose is too high. They also interact with many foods and medications, so it's important to follow your prescriber's instructions on when to take them.
