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Jun 12, 2024


TIROSINT or Generic Levothyroxine for Hypothyroidism?

Hypothyroidism is a condition in which your body has insufficient levels of thyroid hormones. This is typically due to an underactive thyroid, leading to decreased hormone production. Thyroid hormones are essential for regulating your body’s energy use and has an impact on many bodily functions. When thyroid hormone levels are low, your metabolism can be slowed down, resulting in symptoms of hypothyroidism such as:

  • Tiredness
  • Weight gain
  • Increased sensitivity to cold
  • Dry skin
  • Feeling depressed
  • Frequent and/or heavy menstrual periods

How Do Levothyroxine and TIROSINT Work

The thyroid gland releases two main hormones: thyroxine (T4) and triiodothyronine (T3). T4 is largely inactive, while T3 is the active form that impacts your cells and metabolism. Levothyroxine is a synthetic form of T4 and is used as a first-line treatment option for hypothyroidism.

Both levothyroxine and TIROSINT contain levothyroxine sodium as their active ingredient. This means they work in the same way by supplementing T4 hormones, which your body can then convert into the active T3 form as needed.

  • Supplementing T4: Both medications provide synthetic T4, which supplements or replaces the deficient thyroid hormone in individuals with hypothyroidism.
  • Conversion to T3: The synthetic T4 is converted to T3 as needed, restoring normal metabolic function and alleviating the symptoms of hypothyroidism.

Inactive Ingredient Differences

One key difference between TIROSINT and generic levothyroxine lies in their inactive ingredients. While both medications contain the same active ingredient, levothyroxine sodium, the inactive ingredients vary and play a role in the medication's stability and absorption.

  • Generic Levothyroxine: Contains butylated hydroxyanisole, colloidal silicon dioxide, crospovidone, ethyl alcohol, magnesium stearate, mannitol, microcrystalline cellulose, povidone, sodium lauryl sulfate, and sucrose. Different strengths of the medication may also include color additives (except for the 50 mcg strength, which is color-free).
  • TIROSINT: Contains gelatin, glycerin, and water. This minimalistic formulation is beneficial for individuals with allergies or sensitivities to the inactive ingredients found in other levothyroxine products.
Importance of Inactive Ingredients

Impact on Stability and Absorption: Although inactive ingredients do not have direct pharmacological activity, they can affect the stability and absorption of the medication. This can lead to fluctuations in thyroid hormone levels when switching between different formulations of levothyroxine.

Dose and Administration

Both Tirosint and generic levothyroxine are typically taken by mouth, once per day. They should be taken on an empty stomach, 30 minutes to 1 hour before breakfast, and at least 4 hours apart from other medications that might affect their absorption.

While both medications are used to treat hypothyroidism, they differ in their dosage forms and available strengths.

Generic Levothyroxine
  • Forms: Tablets
  • Strengths: 25, 50, 75, 88, 100, 112, 125, 150, 175, 200, and 300 mcg
  • Administration: Tablets are usually swallowed whole but can be crushed and mixed with a small amount of water immediately before use. This option is beneficial for individuals who have difficulty swallowing pills, such as young children.
  • Forms: Capsules and Oral solution (TIROSINT SOL)
  • Strengths:13, 25, 37.5, 44, 50, 62.5, 75, 88, 100, 112, 125, 137, 150, 175, and 200 mcg.
  • Administration: Capsules must be swallowed whole and should not be cut, crushed, or chewed. This limits the use of Tirosint to individuals who can swallow pills.
Importance of Multiple Strengths

Levothyroxine is available in many strengths due to its narrow therapeutic window. This means that there is a small margin between the minimum effective dose and the dose that could cause adverse effects. Precise dosing is crucial to avoid under-treatment (hypothyroidism) or over-treatment (hyperthyroidism), both of which can have significant health consequences.

Regular monitoring of thyroid hormone levels (TSH, T4, and T3) is necessary, and the dose of levothyroxine may need to be adjusted periodically. Having a variety of strengths available allows for small, incremental changes to the dose, which is essential for maintaining optimal thyroid function.

Side Effects

The side effects of Tirosint and generic levothyroxine are similar, with both medications causing side effects when the dose may be too high. These side effects can be categorized into various groups:

  • General: Nervousness, irritability, difficulty sleeping, headache, feeling out of breath, feeling hot, irregular menstruation, rashes
  • Heart-related: Palpitations, heart attack
  • Muscle-related: Muscle spasms, tremors, weakness

When taking either medication it’s important to monitor any side effects and maintain open communication with your healthcare provider to ensure your dosage remains both safe and adequate.


The most significant difference between generic levothyroxine and TIROSINT is the price. TIROSINT costs an average of $170 per 30-day supply, while generic levothyroxine averages at $15 per month, less than one-tenth of the price! At Marley Drug you can access generic levothyroxine in longer supply at 6-months for $37 or a 12-month supply for $70.

This makes generic levothyroxine a preferred choice for many individuals in which cost is a major deciding factor. However, if you have private insurance, the cost may not be an issue allowing other factors to play a more significant role in your decision.

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