Uses
Levothyroxine is
used to treat an underactive thyroid (hypothyroidism). It replaces or
provides 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 is important for maintaining normal
mental and physical activity. In children, having enough thyroid hormone
is important for normal mental and physical development.
This medication is
also used to treat other types of thyroid disorders (such as certain
types of goiters, thyroid cancer).
This
medication should not be used to treat infertility unless it is
caused by low thyroid hormone levels.
Side Effects
Hair
loss may occur during the first few months of treatment. This effect is
usually temporary as your body adjusts to this medication. If this effect
persists or worsens, tell your doctor or pharmacist promptly.
Remember
that your doctor has prescribed this medication because he or she has judged
that the benefit to you is greater than the risk of side effects. Many people
using this medication do not have serious side effects.
Tell
your doctor right away if any of these unlikely but serious effects of
high thyroid hormone levels occur: increased sweating,
sensitivity to heat, mental/mood changes (such as nervousness, mood swings),
tiredness, diarrhea, shaking (tremor), headache, shortness of breath,
bone pain, easily broken bones.
Get
medical help right away if any of these rare but serious effects of high
thyroid hormone levels occur: chest pain, fast/pounding/irregular
heartbeat, swelling hands/ankles/feet, seizures.
A
very serious allergic reaction to this drug is rare. However, get
medical help right away if you notice any symptoms of a serious allergic
reaction, including: rash, itching/swelling (especially of the face/tongue/throat),
severe dizziness, trouble breathing.
This
is not a complete list of possible side effects. If you notice other effects not
listed above, contact your doctor or pharmacist.
Precautions
Before
taking levothyroxine, tell your doctor or pharmacist if you are
allergic to it; or if you have any other allergies. This product may
contain inactive ingredients, which can cause allergic reactions or other
problems. Talk to your pharmacist for more details.
Before
using this medication, tell your doctor or pharmacist your medical
history, especially of: increased thyroid hormones (thyrotoxicosis),
decreased adrenal gland function, heart disease (such as coronary
artery disease, irregular heartbeat), high blood pressure, diabetes.
If
you have diabetes, this drug may affect your blood sugar. Check
your blood sugar regularly as directed and share the results with your
doctor. Tell your doctor right away if you have symptoms such as increased
thirst/urination, shakiness, unusual sweating, dizziness, or hunger.
Your doctor may need to adjust your diabetes medication, exercise program,
or diet.
Before
having surgery, tell your doctor or dentist about all the products
you use (including prescription drugs, nonprescription drugs, and herbal
products).
Children
may be more sensitive to certain side effects of this drug, especially headache, vision changes,
and hip/leg pain. High thyroid hormone levels may lead to decreased
bone development/growth and reduced full adult height. Keep all lab/medical
appointments so the doctor can monitor treatment.
Older
adults may be more sensitive to the side effects of this drug, especially
fast/pounding/irregular heartbeat.
Current
information shows that this drug may be used during pregnancy. Tell your
doctor if you are pregnant because your dose may need to be adjusted.
Levothyroxine
passes into breast milk but is unlikely to harm a nursing infant.
Consult your doctor before breast-feeding.