What ingredients are in levothyroxine tablets?
Levothyroxine is a synthetic version of the thyroid hormone thyroxine (T4). In most brands, the “active ingredient” is levothyroxine sodium, plus inactive (non-medicinal) ingredients that can vary by manufacturer and formulation.
Because levothyroxine comes in multiple strengths and brand/generic versions (and some are liquid or soft-gel), the exact ingredients list you need depends on the specific product you have (for example, the brand name and strength shown on the bottle).
Where to find the exact ingredients list for your specific levothyroxine
Check the “Inactive Ingredients” (or “Ingredients” section) on your:
- drug label, or
- package insert (Medication Guide / Prescribing Information).
If you tell me the brand name (or generic manufacturer), strength (such as 25 mcg, 50 mcg, 75 mcg, etc.), and whether it is tablet vs. liquid, I can help you pinpoint the matching ingredients list.
Does levothyroxine always contain the same inactive ingredients?
No. Even though levothyroxine sodium is consistent as the active ingredient, the inactive ingredients can differ between products. That matters because:
- excipients can affect tablet appearance, dissolution, and tolerability for some patients, and
- switching between brands/generics may require monitoring thyroid levels.
What about levothyroxine liquid or soft-gel—are the ingredients different?
Yes. Non-tablet formulations typically use different inactive ingredients to help with stability and delivery (for example, solvents or capsule materials). The ingredients list will not match a standard tablet’s inactive ingredients.
Quick check: what to send so I can list the exact ingredients
Reply with any of the following from your bottle/box:
- brand or generic name
- strength (mcg)
- tablet vs. liquid/soft-gel
- manufacturer name (if shown)
Sources: None provided.