Levothyroxine 0.013mg (13mcg) Caps

Levothyroxine (T4) is a synthetic form of the natural thyroid hormone, thyroxine. It is converted to its active metabolite, liothyronine (T3), in peripheral tissues. T3 then enters the cell nucleus and binds to thyroid hormone receptors, which in turn bind to specific DNA sequences (thyroid hormone response elements) to regulate gene expression. This process controls metabolism, growth, and development.

Serious Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high blood pressure, including:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Chest pain or pressure
Fast or abnormal heartbeat
Shortness of breath
Sudden weight gain or swelling in the arms or legs
Headache
Feeling tired or weak
Changes in appetite
Unintentional weight changes
Diarrhea, stomach cramps, or vomiting
Mood changes, such as feeling irritable, nervous, excitable, anxious, or restless
Shakiness
Trouble sleeping
Sensitivity to heat
Excessive sweating
Fever
Muscle cramps
Muscle weakness
Flushing
Bone pain
Changes in menstrual periods

Additional Side Effects in Children:

Hip or knee pain
Limping

Additional Side Effects in Infants:

Changes in the shape of the head and face

Other Possible Side Effects

Like all medications, this drug can cause side effects. Many people may not experience any side effects or may only have mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor:

Hair loss (usually temporary and resolves on its own within the first few months of treatment)

Reporting Side Effects

This is not a complete list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
Certain health conditions, including:
+ An overactive thyroid gland
+ A weak adrenal gland
+ Difficulty swallowing
This list is not exhaustive, and it is crucial to discuss all your health problems with your doctor.

Additionally, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
Your health problems, as this information is necessary to ensure safe use of this medication.

Remember, do not start, stop, or change the dose of any medication without first consulting your doctor to confirm it is safe to do so in conjunction with this medication.

Important Information for All Patients Taking This Medication

It is crucial that you inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. To ensure uninterrupted treatment, do not allow your supply of this medication to run out. Please note that it may take several weeks to experience the full effects of this drug.

Special Considerations

If you have diabetes (high blood sugar), consult with your doctor, as this medication may affect your blood sugar control. Your doctor may need to adjust your diabetes medications. Be sure to monitor your blood sugar levels as directed by your doctor and undergo regular blood tests as advised.

If you are taking biotin or a product containing biotin, stop taking it at least 2 days before having your thyroid levels checked to ensure accurate test results.

Potential Risks and Side Effects

High doses of this medication may increase the risk of developing weak bones (osteoporosis), particularly after menopause. Discuss your risk factors with your doctor, who can help determine if you are at higher risk or answer any questions you may have.

This medication may also affect fertility, potentially leading to difficulties in getting pregnant or fathering a child. If you plan to conceive, consult with your doctor before starting this medication.

Age-Related Considerations

If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.

Pregnancy and Breastfeeding

If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor, who will discuss the benefits and risks of this medication to you and your baby.

Pediatric Patients

If you are giving this medication to a child and their weight changes, consult with your doctor, as the dosage may need to be adjusted. Never give your child more of this medication than prescribed, as this may increase the risk of severe side effects.

In some cases, this medication may affect growth in children and teenagers. Regular growth checks may be necessary, so be sure to discuss this with your doctor.

• Amiodarone (can cause hypo- or hyperthyroidism, alters T4/T3 conversion)
• Oral anticoagulants (e.g., Warfarin - increased anticoagulant effect)
• Sympathomimetics (e.g., Epinephrine, Norepinephrine - increased risk of cardiac events)
• Tyrosine kinase inhibitors (e.g., Sunitinib, Imatinib - can alter thyroid function)
• Ion exchange resins (e.g., Cholestyramine, Colestipol, Sevelamer - decreased levothyroxine absorption)
• Sucralfate (decreased levothyroxine absorption)
• Proton pump inhibitors (e.g., Omeprazole - decreased levothyroxine absorption)
• H2 blockers (e.g., Ranitidine - decreased levothyroxine absorption)
• Calcium carbonate/supplements (decreased levothyroxine absorption)
• Iron supplements (decreased levothyroxine absorption)
• Soy products (decreased levothyroxine absorption)
• Orlistat (decreased levothyroxine absorption)
• Rifampin (increased levothyroxine metabolism)
• Phenytoin (increased levothyroxine metabolism, decreased protein binding)
• Carbamazepine (increased levothyroxine metabolism, decreased protein binding)
• Sertraline (may increase levothyroxine requirements)
• Estrogens (increased TBG, may increase levothyroxine requirements)
• Androgens (decreased TBG, may decrease levothyroxine requirements)

• Antacids (aluminum, magnesium hydroxide - decreased levothyroxine absorption)
• Dietary fiber (decreased levothyroxine absorption)
• Grapefruit juice (potential for decreased absorption, though clinical significance debated)
• Beta-blockers (may decrease peripheral conversion of T4 to T3)
• Corticosteroids (may decrease peripheral conversion of T4 to T3)
• Insulin/Oral hypoglycemics (levothyroxine may increase blood glucose, requiring dose adjustment of antidiabetics)
• Digoxin (levothyroxine may decrease digoxin levels)

• Not available

• Fatigue
• Weight changes (gain or loss)
• Cold intolerance
• Constipation
• Dry skin
• Hair loss
• Bradycardia (slow heart rate)
• Depression
• Memory impairment
• Muscle aches
• Nervousness
• Palpitations
• Tremor
• Heat intolerance
• Diarrhea
• Insomnia
• Weight loss (unexplained)

Levothyroxine is essential for normal fetal development and should be continued throughout pregnancy. Thyroid hormone requirements often increase during pregnancy (by 25-50% or more), requiring dose adjustments based on TSH monitoring.

Levothyroxine is compatible with breastfeeding. Only small amounts are excreted into breast milk, and it is not expected to cause adverse effects in breastfed infants. Maternal thyroid hormone requirements typically return to pre-pregnancy levels postpartum.

Dosing is weight-based and higher per kg in younger children due to higher metabolic rates. Regular monitoring of TSH and Free T4 is crucial to ensure proper growth and neurocognitive development. Capsules may be opened and contents mixed with a small amount of water or breast milk for administration to infants/young children.

Lower initial doses (e.g., 12.5-25 mcg/day) are recommended, especially in patients with underlying cardiovascular disease, due to increased sensitivity to thyroid hormones and potential for cardiac adverse effects. Dose adjustments should be made in smaller increments and less frequently. TSH monitoring remains key.

• Levothyroxine is a narrow therapeutic index drug; small changes in dose can have significant clinical effects.
• Consistency is key: advise patients to take it at the same time each day, preferably in the morning on an empty stomach, 30-60 minutes before food or other medications.
• Many drugs and foods interfere with levothyroxine absorption; counsel patients on separation times.
• Do not use for weight loss; it is ineffective and potentially dangerous.
• TSH is the primary lab test for monitoring, but Free T4 may be useful in specific situations (e.g., central hypothyroidism, TSH-secreting pituitary adenoma, or when TSH is unreliable).
• Patients may require higher doses during pregnancy, with certain medications (e.g., estrogen, sertraline), or with malabsorption syndromes.
• Patients may require lower doses with aging, after delivery, or with certain medications (e.g., androgens, amiodarone).

• Liothyronine (T3, Cytomel) - used in specific cases, often for short-term TSH suppression or in combination with levothyroxine.

If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it is a good idea to check with your pharmacist for more information. If you have any questions or concerns about this medication, consult with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.