Please see Full Prescribing Info & BOXED WARNING
IMPORTANT SAFETY INFORMATION AND USE
IMPORTANT SAFETY INFORMATION
- Thyroid hormones, including SYNTHROID, should not
be used either alone or in combination with other drugs
for the treatment of obesity or weight loss. In patients
with normal thyroid levels, doses of SYNTHROID used
daily for hormone replacement are not helpful for weight
loss. Larger doses may result in serious or even life-
threatening events, especially when used in combination
with certain other drugs used to reduce appetite. - Do not use SYNTHROID if you have uncorrected adrenal
problems. - Use SYNTHROID only as ordered by your doctor. Taking
too much or too little SYNTHROID may lead to negative
effects on growth and development, heart function, bone
health, reproductive function, mental health, digestive
function, and changes in blood sugar and cholesterol
metabolism in adult or pediatric patients. - Taking too much levothyroxine may affect your heart,
especially if you are elderly or have heart disease. Tell your
doctor immediately if you have any signs of increased
heart rate, chest pain, or an irregular heartbeat. - Tell your doctor about any other medical conditions
you may have, especially heart disease, diabetes, blood
clotting problems, and adrenal or pituitary gland problems.
The dose of other drugs you may be taking to control
these conditions may have to be changed while you are
taking SYNTHROID. If you have diabetes, check your blood
sugar levels and/or the glucose in your urine, as ordered by
your doctor, and immediately tell your doctor if there are
any changes. If you are taking blood thinners, your blood
clotting status should be checked often. - Taking too much levothyroxine has been associated with
increased bone loss, especially in women after menopause. - Tell your doctor if you are pregnant or breastfeeding or are
thinking of becoming pregnant while taking SYNTHROID.
Your dose of SYNTHROID may need to be increased
during your pregnancy. - Tell your doctor if you start experiencing any of the
following symptoms: rapid or abnormal heartbeat,
chest pain, difficulty catching your breath, leg cramps,
headache, nervousness, irritability, sleeplessness, shaking,
change in appetite, weight gain or loss, vomiting, diarrhea,
increased sweating, difficulty tolerating heat, fever,
changes in menstrual periods, swollen red bumps on the
skin (hives) or skin rash, or any other unusual medical
event. - Partial hair loss may occur during the first few months you
are taking SYNTHROID. - Tell your doctor if you are taking any other drugs, including
prescription and over-the-counter products. - Products such as iron and calcium supplements
and antacids can lower your body’s ability to absorb
levothyroxine, so SYNTHROID should be taken 4 hours
before or after taking these products. - Tell your doctor or dentist that you are taking SYNTHROID
before any surgery. - Use SYNTHROID only as ordered by your doctor. Take
SYNTHROID as a single dose, preferably on an empty
stomach, one-half to one hour before breakfast. - Once your doctor has found your specific SYNTHROID
dose, it is important to have periodic lab tests and clinical
evaluations to assess your treatment response. - Foods like soybean flour, cottonseed meal, walnuts,
and dietary fiber may cause your body to absorb less
SYNTHROID from the gastrointestinal tract. Grapefruit
juice may cause your body to absorb less levothyroxine
and may reduce its effect. Let your doctor know if you eat
these foods, as your dose of SYNTHROID may need to be
adjusted. - It may take several weeks before you notice an
improvement in your symptoms.
This is the most important safety information you should
know about SYNTHROID. For more information, talk with
your doctor.
USE
SYNTHROID® (levothyroxine sodium) tablets, for oral use
is a prescription, man-made thyroid hormone that is used
to treat a condition called hypothyroidism in adults and
children, including infants. It is meant to replace a hormone
that is usually made by your thyroid gland. Generally, thyroid
replacement treatment is to be taken for life. SYNTHROID
should not be used to treat noncancerous growths or
enlargement of the thyroid in patients with normal iodine
levels, or in cases of temporary hypothyroidism caused by
inflammation of the thyroid gland (thyroiditis).
You are encouraged to report negative side effects
of prescription drugs to the FDA. Visit www.fda.gov/
medwatch or call 1-800-FDA-1088.
If you are having difficulty paying for your medicine,
AbbVie may be able to help. Visit AbbVie.com/
PatientAccessSupport to learn more.
Please see the full Prescribing Information, including
BOXED WARNING, or visit
https://www.rxabbvie.com/pdf/synthroid.pdf.
© 2026 AbbVie. All rights reserved. Synthroid® and its
design are registered trademarks of AbbVie Inc.
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