Synthroid is a brand name for Levothyroxine, a medication used to treat hypothyroidism, a condition characterized by an underactive thyroid gland. The thyroid gland is responsible for producing thyroid hormones that regulate various bodily functions, including metabolism. In hypothyroidism, the thyroid gland does not produce enough thyroid hormones, leading to a sluggish metabolism and a variety of symptoms.

Drug Name: Synthroid

Active Ingredient: Levothyroxine

Synthroid tablets



Form: Tablet

Type: Generic

Prescription Required: Rx

Availability: In Stock

Synthroid is a synthetic form of the hormone thyroxine (T4) and is designed to replace the insufficient thyroid hormone levels in the body. It works by increasing the levels of thyroid hormones in the bloodstream, helping to restore normal metabolic processes and alleviate the symptoms of hypothyroidism.

Medicine is available in tablet form and is typically taken orally once a day, preferably in the morning on an empty stomach. The dosage of Synthroid varies depending on factors such as the individual's age, weight, severity of hypothyroidism, and other underlying medical conditions.

Regular monitoring of thyroid hormone levels through blood tests is typically required while taking Synthroid to ensure that the dosage is appropriate and to make any necessary adjustments. It may take several weeks or months of treatment with Levothyroxine to reach the optimal hormone levels and experience symptom relief.

How to use

To use Synthroid effectively, follow these guidelines:

  1. Take it on an empty stomach: Levothyroxine is typically taken in the morning on an empty stomach, at least 30 minutes to 1 hour before breakfast. Food, especially calcium-rich or high-fiber foods, can interfere with the absorption of Synthroid.
  2. Swallow the tablet whole: Take tablets with a full glass of water. Do not crush, chew, or split the tablet.
  3. Consistency is key: Take medicine at the same time each day to maintain consistent hormone levels in your body. This helps ensure the medication's effectiveness.
  4. Avoid interacting substances: Certain medications, supplements, and foods may interact with Synthroid, affecting its absorption or effectiveness.
  5. Be patient: It may take time for Synthroid to reach its full effect and for you to experience symptom relief. Be patient and continue taking the medication as prescribed.


The following are general dosage guidelines for Synthroid:

  1. Starting dosage: The typical starting dosage for adults with hypothyroidism is 25-50 micrograms (mcg) once daily. For elderly patients or those with underlying heart conditions, the starting dosage may be lower, usually around 12.5-25 mcg once daily.
  2. Maintenance dosage: The maintenance dosage for most adults usually ranges from 75-125 mcg once daily. However, this can vary depending on your specific needs and response to the medication.
  3. Pediatric dosage: Children with hypothyroidism may require different dosages based on their age and weight. The initial dosage is generally lower, and adjustments are made based on regular monitoring and growth development.
  4. Pregnancy dosage: Pregnant women with hypothyroidism may need an increased dosage of Synthroid to support both their own thyroid function and the developing fetus.

Side effects

Synthroid may cause side effects, although not everyone experiences them. Common side effects can include:

  1. Headache: Some individuals may experience headaches as a side effect of Synthroid.
  2. Nervousness or irritability: Medicine can sometimes lead to increased nervousness or irritability.
  3. Tremors: In some cases, individuals may experience slight trembling or tremors.
  4. Palpitations or increased heart rate: Levothyroxine may cause an increase in heart rate or palpitations, especially if the dosage is too high.
  5. Changes in appetite: Synthroid can affect appetite, causing either an increase or decrease in appetite.
  6. Sleep disturbances: Some individuals may experience difficulties sleeping or changes in sleep patterns.
  7. Sweating: Excessive sweating or increased perspiration can be a side effect of Synthroid.
  8. Flushing or heat intolerance: Drug can sometimes cause a sensation of warmth or increased sensitivity to heat.
  9. Hair loss: In rare cases, Synthroid may lead to temporary hair loss, especially during the first few months of treatment.
  10. Menstrual irregularities: Some women may experience changes in their menstrual cycle while taking Synthroid.

It is important to note that these side effects are not exhaustive, and some individuals may experience other side effects.

Additionally, allergic reactions to Synthroid are rare but can occur. Seek immediate medical attention if you experience signs of an allergic reaction, such as difficulty breathing, hives, or swelling of the face, lips, tongue, or throat.


To properly store Synthroid, follow these guidelines:

  1. Store at room temperature: Keep Synthroid at a temperature between 68°F (20°C) and 77°F (25°C). Avoid exposing it to extreme heat or cold.
  2. Protect from moisture: Keep the medication in its original container with the cap tightly closed. Protect it from moisture, including humidity and damp environments.
  3. Keep away from light: Store medicine away from direct sunlight and sources of intense light. Store it in a dark place, such as a closed cabinet or drawer.
  4. Avoid storing in the bathroom: Do not store tablets in the bathroom, as the humidity and temperature fluctuations can affect its stability.
  5. Keep out of reach of children and pets: Store Synthroid in a secure location out of the reach of children and pets to prevent accidental ingestion.
  6. Do not use expired medication: Check the expiration date on the medication label and discard any expired Levothyroxine. Expired medication may not be effective and should not be used.
  7. Properly dispose of unused medication: If you have any unused or expired Synthroid, follow the appropriate guidelines for medication disposal in your area. Do not dispose of it in the regular trash or flush it down the toilet unless instructed to do so.


An overdose of Levothyroxine can have serious consequences and should be treated as a medical emergency. If you suspect an overdose or have taken more Synthroid than prescribed, take the following steps:

  1. Seek immediate medical assistance: Call your local emergency services or go to the nearest emergency room right away. It is important to receive prompt medical attention for an overdose.
  2. Provide information: When you seek medical help, provide the information about the overdose, including the amount of Synthroid taken and the time of ingestion.

Missed Doses

If you miss a dose of Synthroid, take the following steps:

  1. Take it as soon as you remember: If you remember the missed dose within a few hours of the scheduled time, take the missed dose as soon as possible. If it is close to the time for your next dose, skip the missed dose and resume your regular dosing schedule.
  2. Do not double the dose: Do not take a double dose to make up for the missed one. Taking more than the prescribed amount can increase the risk of side effects and may not be beneficial.
  3. Follow your regular schedule: Continue taking Synthroid according to your regular dosing schedule. It is important to maintain a consistent routine to keep your thyroid hormone levels stable.

Remember, consistency in taking Synthroid is crucial for its effectiveness in managing hypothyroidism. Missing a single dose is generally not a cause for concern, but if you frequently miss doses, it can affect your thyroid hormone levels and may require adjustment of your medication.

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