Yes, there is a generic for Tirosint. Lannett Company launched an authorized generic version of Tirosint (levothyroxine sodium capsules) in November 2020. However, the generic only applies to the gel capsule form. There is no generic available for Tirosint-SOL, the liquid formulation.
What the Generic Version Is
The generic is sold as Levothyroxine Sodium Capsules USP. It’s classified as an “authorized generic,” meaning the brand-name manufacturer licensed another company to produce and sell it. Authorized generics use the same formulation as the original, which distinguishes them from standard generics that simply need to prove bioequivalence.
The retail price of generic levothyroxine starts around $15 for a 30-day supply, though the exact cost for the capsule form varies by pharmacy and insurance coverage. Brand-name Tirosint is significantly more expensive. If cost is a factor, asking your pharmacist whether the generic capsule is in stock can save you a meaningful amount each month.
Why Tirosint’s Formulation Matters
Tirosint isn’t just another levothyroxine product in a different package. Most levothyroxine tablets, including well-known brands like Synthroid and Levoxyl, contain a long list of inactive ingredients: lactose, corn starch, acacia, magnesium stearate, talc, and various dyes. Generic levothyroxine tablets from manufacturers like Mylan add ingredients such as sucrose, sodium lauryl sulfate, and butylated hydroxyanisole.
Tirosint’s soft-gel capsule takes a different approach. The active ingredient is dissolved in glycerin and enclosed in a gelatin shell, with no lactose, no gluten, no dyes, and far fewer additives overall. This minimal formulation was developed specifically for people who have allergies or sensitivities to the fillers found in standard tablets, and for those with absorption issues related to gastrointestinal conditions.
If you’re considering the generic capsule as a substitute, the key question is whether it shares this same simple ingredient profile. Because Lannett’s product is an authorized generic of Tirosint, it uses the same capsule formulation. That’s a meaningful distinction from switching to a generic levothyroxine tablet, which would contain an entirely different set of inactive ingredients.
Switching Between Brand and Generic
The FDA classifies levothyroxine as a narrow therapeutic index drug. That means even small differences in how much of the medication your body absorbs can push your thyroid levels out of range. Too little absorption leads to persistent hypothyroid symptoms like fatigue and weight gain. Too much can cause heart palpitations, anxiety, and bone loss over time.
Because of this narrow window, the FDA requires generic levothyroxine capsules to meet stricter bioequivalence standards than most other generics. Manufacturers must run a fully replicated crossover study, where the same subjects take both the brand and generic versions multiple times, and the results are scaled against the variability of the brand-name product itself. This design is more rigorous than the standard single-crossover study used for most generic drugs.
Even with these tighter standards, many endocrinologists recommend retesting your thyroid levels (specifically TSH) about six to eight weeks after any switch between levothyroxine products, whether that’s brand to generic, generic to brand, or one generic to another. This isn’t because the generic is inferior. It’s because your dose may have been fine-tuned to a specific product’s absorption profile, and even a small shift can matter when the therapeutic window is tight.
No Generic for the Liquid Form
Tirosint-SOL, the liquid oral solution version, does not have an FDA-approved generic. If your doctor prescribed the liquid specifically, perhaps because you have difficulty swallowing capsules or because the liquid formulation works better for your absorption needs, there is currently no lower-cost equivalent available.
Available Dosage Strengths
Tirosint capsules come in 13 strengths, ranging from 13 mcg up to 200 mcg. The authorized generic covers this same range. This is worth noting because levothyroxine dosing is highly individualized, often adjusted in small increments of 12.5 to 25 mcg. Having the full range of strengths available in the generic means your pharmacy should be able to fill your exact dose without needing to split or combine capsules.
If your pharmacy doesn’t carry the generic capsule, it’s worth calling around. Not every pharmacy stocks it, and some may default to dispensing the brand or offering a generic tablet instead. Specifying that you want the generic levothyroxine sodium capsule, not a tablet, ensures you get the formulation your prescription calls for.