Levoxyl (Levothyroxine)

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.

Storage

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.

Uses

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.

Dosage

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.

Overdose

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.

Diabetes

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.