Levo-Thyroxine (Synthetic)

Description

Levo-Thyroxine (Synthetic) is primarily used to treat Hypothyroidism, a condition where the thyroid gland (a butterfly-shaped organ located in the base of the neck) does not produce sufficient quantities of the required hormones. Levo-Thyroxine (Synthetic) is also used to treat certain other disorders associated with the thyroid gland. It replaces a hormone normally produced by the thyroid gland to regulate the body's energy and metabolism. Levo-Thyroxine (Synthetic) will be prescribed by your doctor after determining your thyroid hormone levels. Levo-Thyroxine (Synthetic) may cause side effects such as excessive sweating, increased hunger, tremors or shaking of hands and legs, heat intolerance, nausea, and vomiting, diarrhoea, weight loss, restlessness, irregular heartbeat, etc. Consult your doctor if the side effects persist for a long time. Levo-Thyroxine (Synthetic) should be taken in the morning on an empty stomach, at least 30-60 minutes before breakfast. Take this medication at the same time every day for better results and to decrease the likelihood of a missed dose. Levo-Thyroxine (Synthetic) should be avoided if you are allergic to it or have heart conditions or hyperthyroidism (a condition where the thyroid gland secretes excess quantities of thyroid hormones), thyrotoxicosis (a condition where extremely high levels of thyroid hormones secreted by the thyroid gland show effects on the tissue level) or adrenal insufficiency (a condition where the adrenal glands which are present above the kidney, cannot secrete sufficient quantities of steroidal hormones). Levo-Thyroxine (Synthetic) use may cause weight loss, but it should not be prescribed or taken to treat obesity. Inform your doctor if you have diabetes, as Levo-Thyroxine (Synthetic) may cause altered blood sugar levels. Levo-Thyroxine (Synthetic) is safe for children and can be used during pregnancy and while breastfeeding. Consult your doctor if you are pregnant, trying to get pregnant, or are breastfeeding before using this medicine.

Side effects

Major & minor side effects for Levo-Thyroxine (Synthetic)

  • Shaking and trembling of arms and feet
  • Headache
  • Nausea and Vomiting
  • Diarrhoea
  • Abdominal cramps
  • Nervousness and irritability
  • Sleeplessnes
  • Excessive sweating
  • Fever
  • Changes in menstrual cycle
  • Temporary hair loss
  • Chest pain and discomfort
  • Rapid or irregular heartbeat
  • Thyrotoxic crisis
  • Weight loss
  • Increased appetite
  • Heat intolerance

Uses of Levo-Thyroxine (Synthetic)

What is it prescribed for?

  • Hypothyroidism
  • Thyroid cancer
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Concerns

Commonly asked questions

  • Onset of action
    The time taken by Levo-Thyroxine (Synthetic) to show its effect is one to two hours after intake.
  • Duration of effect
    The duration for which Levo-Thyroxine (Synthetic) remains effective in your body is subject to vary based on the thyroid hormone levels.
  • Safe with alcohol?
    Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.
  • Is it habit forming?
    No habit-forming tendencies were reported for Levo-Thyroxine (Synthetic).
  • Usage in pregnancy?
    Levo-Thyroxine (Synthetic) is safe for use during pregnancy. Consult your doctor before taking this medicine.
  • Usage while breast-feeding?
    Levo-Thyroxine (Synthetic) is safe for use while breastfeeding. Consult your doctor before taking this medicine.

Allergy

Levo-Thyroxine (Synthetic) is not recommended for use if you are allergic to it. Inform your doctor if there is any swelling or itching on any part of your body.

Thyrotoxicosis

Thyrotoxicosis is a condition where you have extremely high thyroid hormone concentrations in your body due to excessive hormone production from the thyroid gland. Levo-Thyroxine (Synthetic) is not recommended for use if you have thyrotoxicosis as it may cause undesirable effects.

Adrenal insufficiency

Levo-Thyroxine (Synthetic) is not recommended for use in people with an untreated Adrenal insufficiency. It is a condition where the adrenal glands (small, triangular-shaped glands located on top of both kidneys) do not produce a sufficient quantity of steroidal hormones. If you have adrenal insufficiency, the use of Levo-Thyroxine (Synthetic) may make your condition worse.

Acute myocardial infarction

Levo-Thyroxine (Synthetic) is not recommended for use if you have recently experienced a heart attack (decreased blood flow to the heart).
Warnings for special population

Pregnancy

Levo-Thyroxine (Synthetic) is safe for use during pregnancy. Consult your doctor before taking this medicine.

Breast-feeding

Levo-Thyroxine (Synthetic) is safe for use while breastfeeding. Consult your doctor before taking this medicine.
General warnings

Other medicines

Inform your doctor about all the medicines you are using, including dietary supplements and herbal preparations before starting treatment with Levo-Thyroxine (Synthetic) since the likelihood of interactions is significantly high.

Other diseases

Inform your doctor about the medical conditions you may have or had before starting treatment with Levo-Thyroxine (Synthetic). Your doctor may make appropriate adjustments in the dose and the duration of treatment based on your clinical condition.

Thyroid nodules

Levo-Thyroxine (Synthetic) should be used with extreme caution if you have thyroid nodules, as it may lead to thyrotoxicosis (action of excess thyroid hormone in the body leading to adverse effects). Its use is contraindicated if the serum TSH level is already suppressed.

Use in postmenopausal women

Levo-Thyroxine (Synthetic) is not recommended for use in postmenopausal women with osteoporosis (a condition that causes brittle and weak bones), heart problems, or any other systemic illness. Long-term use of this medicine may cause a decrease in bone mineral density, which may increase the risk of fractures.

Treatment of obesity

Levo-Thyroxine (Synthetic) should not be used for the treatment of obesity, especially if there are normal thyroid hormone levels.

Treatment of infertility

Levo-Thyroxine (Synthetic) should not be used for the treatment of male/female infertility unless associated with low thyroid hormone levels.

Dose adjustments

Appropriate dose adjustments will be made based on your clinical condition, use of other medicines, food habits, and other parameters. Under-dosing or overdosing may lead to severe side effects.

Use in elderly

Levo-Thyroxine (Synthetic) should be used with caution in the elderly since the risk of side effects are significantly high.

Missed Dose

Avoid missing a scheduled dose of Levo-Thyroxine (Synthetic). If you miss a dose, take it as soon as you remember. However, if it is almost time for the next scheduled dose, skip the missed dose. Do not double your dose to make up for the missed one.

Overdose

Contact your doctor immediately if you suspect an overdose with Levo-Thyroxine (Synthetic). Symptoms may include a headache, shaking and trembling of hands and feet, nervousness, irritability, chest pain, shortness of breath, fast and pounding heartbeats, etc.
All drugs interact differently for person to person. You should check all the possible interactions with your doctor before starting any medicine.
Interaction with Alcohol

Description

Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.

Instructions

Interaction with alcohol is unknown. It is advisable to consult your doctor before consumption.
Interaction with Medicine

Carbamazepine

Phenytoin

Warfarin

Ethinyl Estradiol

Rifampicin

Epinephrine

Phenobarbital

Ketamine

Testosterone

Amphetamine

Antacids containing calcium/magnesium/aluminum

Insulin and other antidiabetic medicines

Disease interactions

Cardiovascular disease

Levo-Thyroxine (Synthetic) should be used with caution if you have any heart or vascular (related to blood vessels) conditions. Your doctor will start the treatment at the lowest possible dose with frequent monitoring of your heart function. Your doctor may make the necessary dose adjustments if the symptoms of your heart condition worsen.

Diabetes

Levo-Thyroxine (Synthetic) should be used with caution if you have diabetes (increased blood sugar level) as there is a risk of your condition worsening. Your doctor will make the necessary dose adjustments to Levo-Thyroxine (Synthetic) and/or any antidiabetic medications you may be taking. Your doctor may also prescribe regular monitoring of your blood sugar levels during the treatment period.
Food interactions
Food items rich in calcium and iron may reduce the absorption and therapeutic effects of Levo-Thyroxine (Synthetic). There should be a minimum time gap of four hours between the consumption of these food items and Levo-Thyroxine (Synthetic).
Avoid consuming grapefruit juice, infant soy formula, soybean flour, cottonseed meal, walnuts, and high-fibre foods while undergoing treatment with Levo-Thyroxine (Synthetic). These foods affect the absorption of Levo-Thyroxine (Synthetic), thus decreasing its therapeutic effects.
Medicines or food supplements containing multivitamins with minerals may reduce the effects of Levo-Thyroxine (Synthetic) if taken together. There should be a minimum time gap of four hours between the consumption of multivitamins with minerals and Levo-Thyroxine (Synthetic). Inform your doctor of all your current medicines including herbal products before starting treatment with this medicine.
Lab interactions
Information not available.
Take Levo-Thyroxine (Synthetic) exactly as prescribed by your doctor. Take it on an empty stomach, at least 30-60 minutes before breakfast. Do not take Levo-Thyroxine (Synthetic) in larger or smaller quantities than prescribed. Do not take any other medications like antacids, calcium or iron supplements, and multivitamins, at least up to four hours of taking Levo-Thyroxine (Synthetic) as they may affect the absorption. Your doctor may recommend regular tests to monitor your hormone levels. Inform your doctor if you notice a significant change in your body weight. The dose may be adjusted accordingly.
Miscelleneous

To be taken on an empty stomach

To be taken in morning

Does not cause sleepiness

How it works
Levo-Thyroxine (Synthetic) works by replenishing and replacing the hormones produced by the thyroid gland.
Legal Status

Approved

Approved

Approved

Approved

Classification

Category

Thyroid drugs

Schedule

Schedule H

Levothyroxine sodium [Internet]. Pubchem.ncbi.nlm.nih.gov. 2017 [cited 3 August 2017]. Available from:

https://pubchem.ncbi.nlm.nih.gov/compound/23666112#section=Top

Drugs, H., 2021. Levothyroxine: MedlinePlus Drug Information. [online] Medlineplus.gov. Available at: < [Accessed 5 December 2021].

https://medlineplus.gov/druginfo/meds/a682461.html>

Accessdata.fda.gov. 2017. LEVO-T® (levothyroxine sodium) tablets, for oral use. [online] Available at: < [Accessed 26 November 2021].

https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021342s023lbl.pdf>

Pernia, S. and DeMaagd, G., 2016. The New Pregnancy and Lactation Labeling Rule. [online] PubMed Central (PMC). Available at: < [Accessed 26 November 2021].

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5083079/>

Ncbi.nlm.nih.gov. 2021. Drugs and Lactation Database (LactMed)- Levothyroxine. [online] Available at: < [Accessed 26 November 2021].

https://www.ncbi.nlm.nih.gov/books/NBK501003/>

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Information on this page was last updated on 3 Jan 2022

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