What is Levoxyl (levothyroxine)?

Levoxyl is a prescription medication that contains the active ingredient levothyroxine sodium. It is primarily used to replace or supplement the thyroid hormone in individuals with an underactive thyroid (hypothyroidism). Levoxyl belongs to a class of drugs called thyroid hormones, and it works by providing the body with synthetic thyroxine (T4), which is the hormone normally produced by the thyroid gland. By restoring adequate thyroid hormone levels, Levoxyl helps regulate various body functions and metabolism. It is available in tablet form and is typically taken once daily, preferably on an empty stomach. Regular monitoring of thyroid hormone levels is important during treatment with Levoxyl to ensure proper dosage adjustments. Common side effects may include headache, fatigue, and changes in appetite. It is important to follow the prescribed dosage and consult a healthcare professional for any concerns or potential drug interactions.

Levoxyl (Levothyroxine)

Prescription Required.

Product of Canada.

Shipped from Canada.

Prescription Required.Product of Canada.Shipped from Canada.

What is Levoxyl (Levothyroxine)?

Levoxyl (levothyroxine) is a medication that can replace or provide additional thyroid hormone to patients that have an underactive thyroid or other such conditions that may impact the thyroid hormone levels within the body. It may also be used in the treatment of certain other thyroid-related conditions, such as thyroid cancer or infertility that is directly associated with low levels of thyroid hormone.

How is Levoxyl Used?

Levoxyl is an oral medication that should be taken daily in the morning. It should be consumed on an empty stomach, no food should be eaten for at least thirty minutes after the medication has been swallowed, and the tablet should be taken with water. Those who use any additional medications that may impact the absorption should be sure to take these medications with a time period of at least four hours before or after taking their Levoxyl to avoid impairing the absorption and efficacy of the medication.

Medications or supplements containing iron (ferrous sulfate) or calcium carbonate, which may affect the absorption of Levoxyl, may be taken four hours before or after the patient consumes their daily dose of Levoxyl. However, patients that use ion exchange resins or bile acid sequestrants should only take these medicines at least four hours after taking Levoxyl.

In the case of younger patients, such as infants and children that may be unable to swallow Levoxyl tablets whole, these tablets may be crushed and mixed with a few teaspoons or milliliters of water to form a suspension that may be more easily consumed by those in this age group. When administered as a suspension, this suspension should be consumed as soon as possible and should not be stored for later use. Parents and caregivers should be aware that soybean infant formula may decrease the absorption of Levoxyl and should not be used in the administration of this medication. Those whose children consume soybean infant formula regularly should consult with their child’s pediatrician regarding the most effective manner of administering in these circumstances.


Levoxyl tablets should be stored at room temperature, ranging between 68°F (20°C) and 77°F (25°C). This medication may be allowed to temporarily be exposed to temperatures as low as 59°F (15°C) or as high as 86°F (30°C). It should be kept away from moisture and light as well.

Keep this medication out of the reach of children at all times.

Levoxyl should not be disposed of in the sink, in the household trash, or by flushing the tablets down the toilet. Patients that no longer need their remaining Levoxyl tablets should consult with their local waste disposal company or pharmacy for further information regarding how to safely dispose of unused tablets.


Levoxyl is prescribed for the treatment of the following conditions:

  • Hypothyroidism (congenital or acquired)
    • Primary (thyroidal)
    • Secondary (pituitary)
    • Tertiary (hypothalamic)
  • Pituitary thyrotropin suppression (TSH suppression)

Levoxyl should not be used to treat patients that are recovering from experiencing subacute thyroiditis or those who may be iodine-sufficient with nontoxic diffuse goiter or with benign thyroid nodules.

How Does Levoxyl Work?

Levoxyl serves as a synthetic replacement for the body’s thyroid hormone if a patient’s thyroid gland is unable to produce the correct levels of this hormone itself. This allows a patient to avoid the symptoms of hypothyroidism and be able to regulate their energy levels. It also allows individuals to properly proceed with any growth still required in younger patients.


Levoxyl is available in tablet form, and it comes in the following 11 strengths:

  • 25 mcg
  • 50 mcg
  • 75 mcg
  • 88 mcg
  • 100 mcg
  • 112 mcg
  • 125 mcg
  • 137 mcg
  • 150 mcg
  • 175 mcg
  • 200 mcg

The dosage required for treatment will vary based on a number of different factors, such as the patient’s cardiovascular status, weight, age, any current medications they may be taking, and any preexisting or comorbid health conditions. The extent to which their levels of thyroid hormone have dropped will also impact the potential dosage a patient may need to receive.

As patients will require regular testing to determine the effectiveness of treatment when using Levoxyl, changes in dosage may also be made depending on the results of these tests.


Patients that have received and ingested too much Levoxyl will exhibit symptoms of hyperthyroidism, and these symptoms may not become evident until multiple days after the initial overdose. Some of the common side effects of overdosing on Levoxyl include disorientation, confusion, and shock. Significant events such as coma, cerebral embolism, and even death have also been reported in overdoses.

If you or someone else taking Levoxyl have overdosed on this medication or suspect an overdose has occurred, please seek medical assistance. Levoxyl may be discontinued or decreased in dosage size temporarily to try to manage the symptoms of an overdose, but individuals who have ingested too much of this medication should seek the advice of their prescribing physician or contact their local Poison Control Center for assistance.

Side Effects

Levoxyl is associated with a variety of potential side effects, with some being more common and tolerable and others being a cause for concern. Please consult with your prescribing physician if you have any problematic or persistent side effects or have any questions about side effects you may be experiencing while using this medication.

The most common side effects of taking Levoxyl include:

  • diarrhea
  • difficulty sleeping
  • feeling anxious
  • headache
  • leg cramps
  • muscle weakness
  • partial hair loss
  • rash on the skin

Some additional side effects may occur and should be discussed with your doctor as soon as possible if they remain persistent or increase in severity while taking Levoxyl. Some of the following side effects require immediate medical attention:

  • appetite changes
  • changes in menstruation
  • chest pain
  • depression
  • diarrhea
  • dry hair or skin
  • fatigue
  • fever
  • hair loss
  • headaches
  • hot flashes
  • insomnia
  • irregular heartbeat
  • irritability
  • leg cramps
  • memory issues
  • muscle aches
  • nervousness
  • rapid heart rate
  • shortness of breath
  • sweating
  • tremors
  • unusual feelings of coldness
  • vomiting
  • weakness
  • weight changes

Warnings & Precautions

Levoxyl is a medication with a very narrow therapeutic index. Patients using this medication for treatment require regular monitoring to ensure that the prescribed dosage of Levoxyl is appropriate for managing their hypothyroidism without resulting in overtreatment or undertreatment of the condition. Both of these scenarios may result in serious adverse health events that can impact a patient’s gastrointestinal function, cognitive function, reproductive function, bone metabolism, emotional state, lipid metabolism, glucose metabolism, and overall development and growth.

Bone Density

In post-menopausal patients, Levoxyl comes with an increased risk of bone resorption as well as a decrease in a patient’s bone mineral density. Individuals in this demographic are often recommended to use the lowest possible doses of Levoxyl for treatment to manage their hypothyroidism while avoiding the risk of negative impacts on their bone mineral density.

Cardiovascular Disease

Patients with preexisting cardiovascular disease, as well as those who are elderly, are at risk of experiencing increased cardiac wall thickness, cardiac contractility, and heart rate. These factors increasing may result in patients experiencing arrhythmias or angina. This typically occurs when overtreatment with Levoxyl has occurred, and patients meeting the criteria for increased cardiovascular risks should be sure to discuss all preexisting cardiovascular conditions with their physician before beginning treatment with Levoxyl.


Patients with diabetes mellitus may experience increased difficulty in managing their glucose levels when using Levoxyl for treatment. This may result in diabetic patients requiring adjustments to their usual insulin requirements and increased self-monitoring to regulate their condition. Any changes in the dosage of their Levoxyl may impact their diabetes management, and these individuals will need to remain aware of these risks when beginning treatment, ending treatment, or adjusting the dosage of Levoxyl during treatment.

Pediatric Age Group

Although Levoxyl may be used in infants and children requiring this medication to manage their hypothyroidism, they will need to be closely monitored throughout treatment to avoid overtreatment as well as undertreatment. Improper thyroid hormone levels in children and infants can result in arrhythmias, aspiration, cardiac overload, craniosynostosis, impaired growth, impaired concentration, and reduced size as an adult. Impaired brain maturation, premature epiphyseal closure, and negative impacts on a child’s intellectual development are also risks of improperly balanced TSH levels.

Children born with congenital hypothyroidism will typically be required to remain on thyroid hormone replacement therapy for life.

Pregnancy and Breastfeeding

As hypothyroidism has been shown to have more risks for a pregnant patient and the individual’s unborn child, Levoxyl is often approved for use in this demographic. This medication has not been associated with any undesirable effects when used by pregnant individuals, and it has not been tied to any increases in the risks of miscarriages or birth defects. Due to the fluctuation of TSH levels in a patient throughout the duration of a pregnancy, pregnant individuals will need to be closely monitored and have their Levoxyl dosage adjusted accordingly to properly manage their hypothyroidism.

Levoxyl has been shown to pass through breast milk for those using the medication who desire to breastfeed. However, there is not a sufficient amount of information to determine the level of risk to the breastfed infant that is receiving the patient’s milk. Managing breastfeeding individuals’ hypothyroidism with Levoxyl appears to normalize the production of breast milk in these patients, but those desiring to continue using Levoxyl for treatment while actively breastfeeding should discuss any potential risks with their physician as well as their child’s pediatrician.

Additional Medical Conditions

If you have any of the following medical conditions, exercise caution when taking Levoxyl and discuss your medical history with your doctor before beginning this medication:

  • adrenal gland conditions
  • anemia (low red blood cell count)
  • clotting disorders
  • diabetes
  • drug allergies
  • food allergies
  • heart disease
  • osteoporosis
  • pituitary gland conditions
  • pregnant or planning to become pregnant
  • recent radiation therapy involving iodine (e.g., I-131)

Drug Interactions

Speak to your doctor about any medications or herbal supplements you are currently taking before beginning treatment with Levoxyl. Discuss any concerns you may have with your doctor or a trusted pharmacist.

The following medications, drugs, and supplements are known to interact with Levoxyl and may decrease the efficacy of a patient’s treatment with this medication or result in other adverse side effects:

  • 5-Fluorouracil
  • Aluminum hydroxides
  • Amiodarone
  • Anabolic steroids
  • Androgens
  • Antacids
  • Antidepressants
  • Asparaginase
  • Beta-adrenergic antagonists
  • Bile acid sequestrants
  • Calcium carbonate
  • Carbamazepine
  • Cholestyramine
  • Clofibrate
  • Colestipol
  • Colesevelam
  • Dexamethasone
  • Digitalis Glycosides
  • Estrogens
  • Fenamates
  • Ferrous sulfate (iron)
  • Furosemide
  • Glucocorticoids
  • Heparin
  • Heroin
  • Hydantoins
  • Insulins
  • Ion exchange resins
  • Kayexalate
  • Ketamine
  • Magnesium hydroxides
  • Methadone
  • Mitotane
  • NSAIDs (non-steroidal anti-inflammatory drugs)
  • Oral contraceptives
  • Orlistat
  • Phenobarbital
  • Proton pump inhibitors
  • Propranolol
  • Rifampin
  • Salicylates
  • Sevelamer
  • Simethicone
  • Slow-release nicotinic acid
  • Sucralfate
  • Sympathomimetics
  • Tamoxifen
  • Tyrosine-kinase inhibitors

Foods and Beverages That Impact Levoxyl Treatment

The following foods and beverages are known to interact with Levoxyl and negatively impact absorption and treatment with the medication:

  • Cotton seed meal
  • Dietary fiber
  • Grapefruit juice
  • Soybean flour
  • Walnuts

Alternative Medications

For patients who are unable to take Levoxyl or experiencing significant adverse side effects, alternative medications may be used to treat some of the associated conditions for which this medication is commonly prescribed:

  • Armour Thyroid (desiccated thyroid)
  • Cytomel (liothyronine)
  • Euthyrox (levothyroxine)
  • Synthroid (levothyroxine)
  • Thyrolar (liotrix)
  • Tirosint (levothyroxine)
  • Unithroid (levothyroxine)

In some cases, treatment with selenium, vitamin B12, and vitamin D may alleviate the symptoms of low thyroid hormone levels and promote good thyroid health in those with less severe conditions.

Frequently Asked Questions

The active ingredient present in Levoxyl is levothyroxine sodium. The following inactive ingredients are also present in this medication: coloring additives, sodium bicarbonate, calcium sulfate dihydrate, magnesium stearate, croscarmellose sodium, and microcrystalline cellulose.

Patients that regularly consume the following foods and drinks should consult with their prescribing physician, as these foods and drinks are known to impact the absorption of Levoxyl: dietary fiber, grapefruit juice, walnuts, cotton seed meal, and soybean flour.

Patients using Levoxyl may not notice an improvement in their condition for several weeks as the medication gradually increases their thyroid hormone levels to a suitable range. The symptoms associated with low levels of thyroid hormone will be alleviated as these levels increase and become more stable.

If a patient’s thyroid gland is unable to produce the appropriate amount of thyroid hormone required for normal functioning, a patient will typically need to remain on a replacement therapy medication for the duration of their life. In this case, someone using Levoxyl would need to take the medication indefinitely to manage their symptoms.

Many patients have reported temporary hair loss during their first few months of treatment with Levoxyl. However, this hair loss tends to only be short-term and eventually resolves.

Individuals who are not producing enough thyroid hormone only for a short period of time or who have recently experienced thyroiditis (swelling and inflammation of the thyroid gland) should not use it for treatment. Additionally, those who have difficulties associated with the function of their adrenal glands should also not use Levoxyl.

Levoxyl should be taken exactly as prescribed by a patient’s physician. This is most commonly a daily dose of Levoxyl taken on an empty stomach first thing in the morning and at least 30 to 60 minutes before consuming anything for breakfast.

Levoxyl may cause some patients to experience serious side effects, such as brittle or weakened bones, difficulty with managing diabetes mellitus, or heart-related issues (e.g., arrhythmias, rapid heartbeat, chest pain). However, the side effects most commonly experienced include the following: appetite changes, muscle weakness, leg cramps, diarrhea, chest pain, menstrual changes, tremors, headaches, fever, insomnia, shortness of breath, irritability or anxiety, weight loss, hair loss, and more.

Levoxyl should be stored away from light, moisture, and heat and kept in a temperature range of 68°F (20°C) to 77°F (25°C).

Patients using Levoxyl should avoid consuming any of the following foods or beverages when using this medication as these foods and drinks may impair the absorption and negatively impact the patient’s treatment plan: dietary fiber, cotton seed meal, soybean flour, grapefruit juice, and walnuts.

Levoxyl is prescribed for the treatment of low levels of thyroid hormone in patients and may also be used as a part of the treatment plan for individuals with thyroid cancer.

Levoxyl, as well as any other thyroid hormone medications, should not be used for the purposes of weight loss. These medications are not only ineffective at assisting patients in losing weight but also come with significant health risks associated with higher dosages of these hormones being ingested by individuals who do not require such treatment. Improper use of Levoxyl may even become life-threatening in some cases.

Levoxyl does not directly treat infertility in male or female patients. However, if a patient is struggling with infertility due to hypothyroidism, treatment with Levoxyl will assist in resolving this condition and improving fertility in the affected patient.

Levoxyl use in pediatric patients comes with a number of serious risks. These include slipped capital femoral epiphysis, pseudotumor cerebri, craniosynostosis, impaired growth that may result in reduced adult height, and heart-related conditions. Infants and children using Levoxyl will need to be closely monitored to ensure they are receiving the appropriate dosage of the medication to effectively treat their hypothyroidism without causing serious adverse effects.

Not only does water not impair the absorption of Levoxyl like some other beverages, but the tablets have been reported to cause choking and gagging due to the tablets rapidly dissolving. This medication should be taken with a full glass of water so that its easier to swallow and so that it’s properly absorbed to reduce the likelihood of choking or otherwise experiencing difficulties with ingestion.

Patients that are pregnant or planning to become pregnant should discuss the use of Levoxyl with their physician. In general, the symptoms of hypothyroidism pose more risks to a pregnant patient and their unborn child than the use during pregnancy. However, the patient’s dosage may need to be adjusted throughout pregnancy to ensure proper treatment and safe use of the medication.

Levothyroxine is the primary ingredient and generic form of this type of thyroid hormone replacement medication. Levoxyl is simply one of the name-brand options of levothyroxine available.

If overtreatment or undertreatment occur in patients using Levoxyl, the associated symptoms of these imbalances of the patient’s thyroid hormone levels may lead to changes in weight, such as weight gain or weight loss. However, with proper treatment and the correct dosage, there should not be significant adverse changes in an individual’s weight.