Medically reviewed by Jessica Swirble, PharmD
Last updated on 3/28/2024

Drug Information | Side Effects | Use & Dosage | Request a Prescription

• Brand Name: Synthroid, Tirosint, Levoxyl, Unithroid, Levo-T, Ermeza
  
• Generic Name: Levothyroxine
  
• Uses: Treatment of hypothyroidism and certain thyroid-related conditions
  
• Drug Class: Thyroid hormone replacement
  
• Availability: Prescription only
  
• Generic Status: Yes
  
• Controlled Substance: No
  
  

Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism (underactive thyroid) and certain thyroid-related conditions. It works by replacing or supplementing the thyroid hormone that your body naturally produces.

Hypothyroidism: Levothyroxine is primarily used to treat hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormone. This medication helps regulate thyroid hormone levels in the body, alleviating symptoms such as fatigue, weight gain, cold intolerance, and sluggishness.

Thyroid nodules: In certain cases, levothyroxine may also be used to shrink thyroid nodules or prevent the growth of goiters (enlarged thyroid glands).

Thyroid cancer: In some instances, levothyroxine is prescribed as part of thyroid cancer treatment. It is usually prescribed with radioactive iodine therapy and surgery.

Levothyroxine is a synthetic form of thyroxine (T4), one of the thyroid hormones produced by the thyroid gland. It functions similarly to natural thyroid hormone and helps restore thyroid hormone levels in individuals with hypothyroidism or thyroid-related conditions. Levothyroxine supplementation improves metabolic function and overall well-being in affected individuals.

Note that levothyroxine therapy requires regular monitoring of thyroid function through blood tests to ensure optimal hormone levels are maintained.

Levothyroxine is usually taken orally, on an empty stomach, at least 30 minutes to 1 hour before breakfast or as directed by your healthcare provider. It is recommended that you take it at the same time each day to maintain stable hormone levels.

Consult your healthcare provider for specific instructions on how to take levothyroxine properly.

The effects of levothyroxine on symptoms of hypothyroidism, such as fatigue and cold intolerance, may be noticeable within a few weeks of starting treatment. However, it may take several weeks to months to achieve the desired thyroid hormone levels. It’s important to take levothyroxine consistently to maintain the best treatment outcomes.

While levothyroxine is primarily used to treat hypothyroidism and related conditions, it may also be prescribed for other purposes, including:

• Thyroid hormone replacement therapy after thyroid surgery or radioactive iodine treatment for hyperthyroidism.
  
• Management of certain types of thyroid disorders, such as Hashimoto's thyroiditis.
  
• Thyroid hormone supplementation in individuals with pituitary gland disorders affecting thyroid function.
  

Discuss any alternative uses of levothyroxine with your healthcare provider.

Levothyroxine is available as an oral tablet in various strengths, including 25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 112mcg, 125mcg, 137mcg, 150mcg, 175mcg, 200mcg, and 300mcg. It is also available in oral solution form for pediatric use.

Generic versions of levothyroxine are available under different brand names.

Levothyroxine is a prescription medication. You will need a valid prescription from a licensed healthcare provider to obtain this drug.