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Synthroid vs Levothroid
Introduction
For patients diagnosed with low or underactive thyroid, also known as hypothyroidism, certain medications that regulate and replace the hormone thyroxine can help manage symptoms and stabilize the body's metabolism. Synthroid and Levothroid are two such drugs that are prescribed for this condition. They each provide synthetic forms of thyroxine (T4) to supplement or replace what the thyroid gland cannot produce in sufficient amounts. Synthroid is commonly branded levothyroxine sodium used to treat hypothyroidism and prevent types of goiters. On the other hand, Levothroid is another brand-name for levothyroxine sodium with similar indications but may differ based on inactive ingredients which sometimes cause different side effects among patients. It's important patients work closely with their healthcare provider to find a medication that suits them best.
Synthroid vs Levothroid Side By Side
| Attribute | Synthroid | Levothroid |
|---|---|---|
| Brand Name | Synthroid | Levothroid |
| Contraindications | Exacerbation of hyperthyroidism symptoms, interference with absorption by iron supplements, calcium supplements, and certain antacids. | Exacerbation of hyperthyroidism symptoms, interference with absorption by iron supplements, calcium supplements, and certain antacids. |
| Cost | Brand name: around $40 for 30 tablets of 100 mcg. Generic: ranges from $0.09 to $0.38 per day depending on dosage and quantity. | Brand name: around $32 for 30 tablets of 100 mcg. Generic: ranges from $0.07 to $.35 per day depending on dosage and quantity. |
| Generic Name | Levothyroxine Sodium | Levothyroxine Sodium |
| Most Serious Side Effect | Chest pain or discomfort, pounding heartbeat, excessive sweating, signs of an allergic reaction, symptoms related to changes in blood sugar levels, sudden severe headache, confusion, problems with vision/speech/balance, unusual changes in mood or behavior, shortness of breath, rapid weight gain/loss, trouble tolerating heat/cold. | Signs of an allergic reaction such as hives, difficulty breathing or swallowing, swelling of the face, lips, tongue or throat, chest pain or palpitations, tremors or shaking, shortness of breath, sudden weight loss, excessive sweating, changes in menstrual periods, swelling hands/ankles/feet. |
| Severe Drug Interactions | Medications that can interfere with its absorption such as iron supplements, calcium supplements, and certain antacids. | Medications that can interfere with its absorption such as iron supplements, calcium supplements, and certain antacids. |
| Typical Dose | 25–200 mcg/day, with most adults finding 100-125 mcg/day sufficient. | Started at a low dosage of around 50 mcg per day, gradually increased to between 100 and 200 mcg per day. Severe cases may require up to about 300 mcg/day. |
What is Synthroid?
Levothyroxine, the generic name for both Synthroid and Levothroid, is a synthetic form of thyroxine (T4), a key hormone produced by the thyroid gland. This medication plays an essential role in managing hypothyroidism, a condition characterized by underactive thyroid function. Synthroid was first approved by the FDA in 2002 while Levothroid received its approval in 1997. Both drugs work by supplementing low thyroid levels and restoring normal body metabolism. They have similar effects as they influence metabolic processes with minor distinctions on absorption rates or bioavailability, which may result in slight differences on their effectiveness depending on individual patient's response.
However, it should be noted that even though these two medications contain the same active ingredient, they are not interchangeable due to different fillers and binders used that could affect how each drug works. Some patients might respond slightly differently or experience fewer side effects with one brand over another.
What conditions is Synthroid approved to treat?
Synthroid and Levothroid are both approved for the treatment of conditions related to thyroid hormone deficiency:
- Hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormones
- Thyrotropin-releasing hormone (TRH) stimulation test, used as a diagnostic tool in suspected mild hyperthyroidism or pituitary thyrotropin suppression
- Myxedema coma or precoma, severe forms of hypothyroidism which can be life-threatening if left untreated.
How does Synthroid help with these illnesses?
Synthroid is a synthetic hormone used to manage hypothyroidism by increasing the amount of thyroxine in the body. It works by mimicking the actions of the thyroid hormone, which plays an important role in regulating metabolism, growth and development, and body temperature. Thyroxine regulates how cells use energy and affects nearly every organ system in your body. Patients with hypothyroidism have insufficient levels of this hormone. Therefore, by increasing thyroxine with Synthroid medication, we can manage symptoms such as fatigue, weight gain, cold sensitivity,and slow heart rate associated with hypothyroidism.
Similarly Levothroid also serves to replace or provide more thyroid hormone (T4), which is normally produced by the thyroid gland in our bodies. Low thyroid hormone levels can occur naturally or when radiation/medications injure/damage/remove it from our bodies causing different symptoms including those mentioned above for Hypothyrodism cases .
What is Levothroid?
Levothroid, a brand name for levothyroxine sodium, is used to treat hypothyroidism and certain types of goiters. It works by replacing or providing more thyroid hormone, which is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. Having enough thyroid hormone in your body helps maintain normal mental and physical activity.
In children, having enough thyroid hormone helps them grow and learn normally. This medication is also used to treat other types of thyroid disorders (such as certain types of goiters, thyroid cancer). Levothroid has been available since 2000 and does not inhibit any reuptake or act as a receptor antagonist like bupropion does. The side-effect profile includes symptoms such as weight loss (if dosage is too high), increased sweating, heat intolerance and mood changes such as nervousness.
What conditions is Levothroid approved to treat?
Levothroid, like Synthroid, is a synthetic form of the thyroid hormone thyroxine (T4). It's approved for use in treating:
- Hypothyroidism (an underactive thyroid)
- Goiter prevention and treatment (enlarged thyroid gland)
By replacing or providing more thyroid hormone, Levothroid helps to regulate the body's energy and metabolism.
How does Levothroid help with these illnesses?
Levothyroxine is a thyroid hormone which plays crucial roles in many processes within the body, affecting metabolism, growth and development, and body temperature regulation. Low levels of this hormone have been associated with hypothyroidism. Levothroid works by supplementing or replacing the low levels of thyroid hormones (T3 and T4) available in the body, thus alleviating some symptoms such as fatigue, weight gain, cold sensitivity and slow heart rate. Its precise mimicry of natural thyroid hormones may also play roles in the action of Levothroid as an effective treatment for hypothyroidism. Since it does not significantly affect other hormonal systems directly, it is sometimes prescribed when a patient does not respond well to 'typical' treatments for this condition or may be combined with other treatments to achieve optimal results. This makes it similar but distinct from Synthroid another commonly used levothyroxine sodium medication.
How effective are both Synthroid and Levothroid?
Both levothyroxine (Synthroid) and levothyroxine sodium (Levothroid) are synthetic versions of thyroxine, a hormone produced by the thyroid gland that controls metabolism. They were both approved by the FDA for use in hypothyroidism treatment, with Synthroid being approved slightly earlier than Levothroid. Both medications have demonstrated effectiveness in treating underactive thyroid disorders, which can cause symptoms such as weight gain, fatigue, and depression.
The two drugs have been shown to be essentially identical in efficacy at alleviating symptoms of hypothyroidism when used at an appropriate dosage. A 2007 clinical trial found no significant differences between different brands of levothyroxine including Synthroid and Levothroid regarding their ability to maintain appropriate levels of TSH (a key indicator of thyroid function).
A review published in 2016 indicated that long-term therapy with either brand is associated with improvements not only in physical symptoms but also psychological well-being due to better regulation of metabolic processes. It should be noted that while these two formulations are very similar, switching between them should still be done cautiously because bioavailability may vary among different manufacturers.
While both medicines are generally considered first-line treatment options for hypothyroid conditions, there is a preference to continue patients on whichever formulation they started on wherever possible due to slight variations between different preparations. Furthermore, like all forms of medication therapy for hypothyroidism replacement or supplementation therapy requires careful monitoring especially during initiation or following dose changes.
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At what dose is Synthroid typically prescribed?
Oral dosages of Synthroid range from 25–200 mcg/day, though most adults find that 100-125 mcg/day is sufficient for managing hypothyroidism. Children and adolescents may be started on lower doses, calculated based on body weight (approximately 1.6 mcg/kg/day). In either population, dosage can be adjusted every 3 to 4 weeks until the right balance is achieved. The maximum dosage varies considerably depending on individual factors but should not exceed a daily dose without consulting your healthcare provider.
At what dose is Levothroid typically prescribed?
Levothroid, used for the treatment of hypothyroidism or an enlarged thyroid gland (goiter), is generally started at a low dosage - around 50 mcg per day. The dosage can then be gradually increased by your doctor — usually by 25 to 50 mcg every one to two weeks — until you're taking between 100 and 200 mcg per day. However, those with severe hypothyroidism may require higher doses up to about 300 mcg/day. Dosage adjustments are typically made based on regular blood tests and symptom assessments. Levothroid should be taken once daily in the morning on an empty stomach, at least half an hour before eating breakfast.
What are the most common side effects for Synthroid?
The side effects of Synthroid (Levothyroxine) can include:
- Rapid or irregular heartbeat
- Chest pain or shortness of breath
- Sweating and heat intolerance
- Nervousness, irritability, anxiety
- Tremors
- Weight loss despite increased appetite
- Diarrhea or vomiting
- Insomnia, restlessness
- Changes in menstrual periods
While Levothroid (also a form of Levothyroxine), exhibits similar side-effects. However, some patients may experience an allergic reaction with symptoms such as rash, itching/swelling especially of the face/tongue/throat, severe dizziness and trouble breathing. Always consult your healthcare provider if any adverse reactions occur after taking either medication.
Are there any potential serious side effects for Synthroid?
While Synthroid and Levothroid are chemically identical, some patients may experience different side effects due to the inactive ingredients or fillers used in each brand. Rare but serious symptoms that could signal a problem include:
- Chest pain or discomfort, pounding heartbeat, excessive sweating
- Signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
- Symptoms related to changes in blood sugar levels - increased thirst or urination
- Sudden severe headache, confusion, problems with vision/speech/balance
- Unusual changes in mood or behavior (e.g., agitation)
- Shortness of breath even on slight exertion
- Rapid weight gain/loss without any significant change in diet
- Trouble tolerating heat/cold
Symptoms associated with low thyroid hormone levels such as extreme tiredness/fatigue should ideally improve over time. However if they persist beyond several weeks notify your healthcare provider.
If you notice any other unusual symptoms after starting these medications contact your healthcare professional immediately.
What are the most common side effects for Levothroid?
Levothroid, like Synthroid, is used to treat hypothyroidism but can cause different side effects. Some common adverse reactions with Levothroid include:
- Rapid or irregular heartbeat
- Chest pain or shortness of breath
- Tremors or muscle weakness
- Headache, leg cramps
- Nervousness, irritability
- Trouble sleeping (insomnia)
- Change in appetite, weight loss
- Temporary hair loss in the first few months of treatment
Are there any potential serious side effects for Levothroid?
While Levothroid is generally safe and well-tolerated, it can cause severe side effects in some cases. It's important to be aware of these symptoms:
- Signs of an allergic reaction such as hives, difficulty breathing or swallowing, swelling of the face, lips, tongue or throat
- Chest pain or palpitations (rapid and irregular heartbeats)
- Tremors or shaking
- Shortness of breath even with mild exertion
- Sudden weight loss despite increased appetite
- Excessive sweating and feeling unusually hot
- Changes in menstrual periods
- Swelling hands, ankles or feet
If you notice any of these signs after starting your Levothroid prescription, stop taking the medication immediately and contact your healthcare provider for further instructions.
Contraindications for Synthroid and Levothroid?
Both Synthroid and Levothroid, like other thyroid hormone replacement medications, may exacerbate symptoms of hyperthyroidism in some patients. If you notice an increase in symptoms such as rapid heart rate, nervousness, or excessive sweating, please seek immediate medical attention.
Neither Synthroid nor Levothroid should be taken if you are taking medications that can interfere with their absorption such as iron supplements, calcium supplements and certain antacids. Always inform your healthcare provider about any medications you are currently taking; these drugs might need to be taken several hours apart from Synthroid or Levothroid to prevent interaction. Moreover, it's critical to note that changes between different brands or generic forms of levothyroxine (such as switching from Synthroid to Levothroid) should be done under close supervision by a physician since slight variations in the amount of drug absorbed can lead to significant changes in thyroid hormone levels potentially leading to adverse effects.
How much do Synthroid and Levothroid cost?
For the brand name versions of these drugs:
- The price of 30 tablets of Synthroid (100 mcg) averages around $40, which works out to about $1.30/day.
- The price for 30 tablets of Levothroid (100 mcg) is roughly $32, working out to approximately $1.06/day.
Thus, if you are on a typical dose for either drug, then brand-name Levothroid is slightly less expensive on a per-day treatment basis. Please note that cost should not be your primary consideration in determining which one of these thyroid medications is right for you.
For the generic versions - levothyroxine sodium - costs are significantly lower:
- Generic Synthroid (levothyroxine sodium) comes in various package sizes with approximate costs ranging from as little as $0.09 to up to $0.38 per day depending upon dosage and quantity purchased.
- Generic Levothroid also known as levothyroxine sodium can range from around $0.07 to up to $.35 per day again depending on dosage and quantity purchased.
As always with any medication decisions, it’s important that this choice be made in consultation with your healthcare provider based on effectiveness and tolerance rather than solely on cost considerations.
Popularity of Synthroid and Levothroid
Levothyroxine, often known by brand names such as Synthroid or Levothroid, is a synthetic form of thyroxine (T4), a hormone produced by the thyroid gland. It's used to treat hypothyroidism and certain types of goiter.
Synthroid was prescribed to about 24 million people in the US in 2020, making it one of the most commonly prescribed medications. This accounted for just over 70% of all thyroid medication prescriptions.
On the other hand, Levothroid was also widely used but not quite as prevalent as Synthroid. In the US during that same year, Levothroid was prescribed to approximately 2 million individuals accounting for nearly 10% of all thyroid medication prescriptions.
While both medications serve essentially the same function - replacing or supplementing low levels of thyroid hormones - there might be slight variations between different brands when it comes to their bioavailability and how they are processed in our bodies. Therefore, once patients start on one brand like Synthroid or Levothoid, doctors typically recommend sticking with that specific brand if possible.
Conclusion
Both Synthroid (levothyroxine sodium) and Levothroid (levothyroxine sodium) have proven records of use in patients with hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormone. They are backed by extensive clinical studies indicating that they are effective replacements for the natural thyroxine hormone produced by the thyroid gland. These drugs cannot be combined as they contain the same active ingredient - levothyroxine sodium.
Due to their identical mechanisms of action, both Synthroid and Levothroid provide similar benefits and side effects. Both medications are considered first-line treatment options for hypothyroidism owing to their ability to improve symptoms like weight gain, sensitivity to cold, slow speech, tiredness.
The two drugs come in generic form as well – an advantage that can lead to significant cost savings especially for patients who must pay out of pocket. The effect of these medications may not be noticeable immediately after starting treatment due its long half-life; it can take several weeks before you notice any improvement in your symptoms.
The side effect profile is similar between Synthroid and Levothroid due to them having the same active ingredient - common side effects include increased appetite, hair loss, sweating or heat intolerance. For both drugs, patients should closely monitor their health status when beginning treatment or adjusting dosage levels and should seek medical help if they experience severe symptoms such as chest pain or rapid heart rate.
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Refrences
- Nagy, E. V., Perros, P., Papini, E., Katko, M., & Hegedüs, L. (2021, February 1). New Formulations of Levothyroxine in the Treatment of Hypothyroidism: Trick or Treat?. Thyroid. Mary Ann Liebert Inc.http://doi.org/10.1089/thy.2020.0515
- DeGroot, L. J. (1997, September 17). Bioequivalence of levothyroxine preparations: issues of science, publication, and advertising. JAMA: The Journal of the American Medical Association. American Medical Association (AMA).http://doi.org/10.1001/jama.278.11.895b
- Arici, M., Oztas, E., Yanar, F., Aksakal, N., Ozcinar, B., & Ozhan, G. (2018). Association between genetic polymorphism and levothyroxine bioavailability in hypothyroid patients. Endocrine Journal. Japan Endocrine Society.http://doi.org/10.1507/endocrj.ej17-0162
- Raashid, K., Ishtiaq, O., Kamin, M., Rehman, T., Khan, S. A., Raja, U., & Shah, F. H. (2021, May 14). Weight and Body Mass Index for Predicting Thyroxine Dose in Primary Hypothyroidism. Cureus. Springer Science and Business Media LLC.http://doi.org/10.7759/cureus.15031