Key takeaways
Levothyroxine, available under brand names like Synthroid, Euthyrox, and Tirosint Sol, is a thyroid hormone used to treat low thyroid hormone levels (hypothyroidism) and thyroid cancer. Both Synthroid and levothyroxine belong to the same medication class and are lab-made thyroxine (T4) hormone; both are used for similar conditions. The main differences between Synthroid and levothyroxine are that Synthroid is a brand name medication while levothyroxine is generic, and they may contain different inactive ingredients such as fillers and binders. Both medications are taken orally, usually once a day on an empty stomach, and require regular blood tests to ensure the correct dosage. Synthroid is available only in tablet form, while levothyroxine offers both tablet and liquid forms in other brand names, such as Tirosint Sol and Thyquidity. Both Synthroid and levothyroxine have similar side effects, like fast heartbeat and weight loss, which usually occur if the dose is too high. They also interact with many foods and medications, requiring careful timing of doses.
