Brand name: Levothyroxine
- Levothroid
Pronounced: SIN-throid
Generic name: Levothyroxine
Other brand names: Levothroid, Levoxyl, Unithroid
Why is Levothyroxine prescribed?
Levothyroxine, a synthetic thyroid hormone may be given in any of the
following cases:
* If your own thyroid gland is not making enough hormone
* If you have an enlarged thyroid (a goiter) or are at risk for developing
a goiter
* If you have certain cancers of the thyroid
* If your thyroid production is low due to surgery, radiation, certain drugs,
or disease of the pituitary gland or hypothalamus in the brain
Most important fact about Levothyroxine
If you are taking Levothyroxine to make up for a lack of natural hormone,
it is important to take it regularly at the same time every day. You
will probably need to take it for the rest of your life.
How should you take Levothyroxine?
Take Levothyroxine as a single dose, preferably on an empty stomach, one-half
to one hour before breakfast. The drug is absorbed better on an empty
stomach.
If an infant or child cannot swallow whole tablets, you may crush
a Levothyroxine tablet and mix it into 1 or 2 teaspoonfuls of water.
While taking Levothyroxine, your doctor will perform periodic blood tests
to determine whether you are getting the right amount.
--If you miss a dose...
Take it as soon as you remember. If it is almost time for your next
dose, skip the one you missed and go back to your regular schedule.
Never take 2 doses at the same time. If you miss 2 or more doses in
a row, consult your doctor.
--Storage instructions...
Keep Levothyroxine in a tightly closed container. Store it at room temperature,
away from light and moisture.
Levothyroxine side effects
Side effects from Levothyroxine, other than overdose symptoms, are rare.
People who are treated with Levothyroxine may initially lose some hair,
but this effect is usually temporary. You may have an allergic reaction
such as a rash or hives. Children may have an increase in pressure
within the skull. Excessive dosage or a too rapid increase in dosage
may lead to overstimulation of the thyroid gland. Notify your doctor
immediately if you develop any if the following symptoms.
* Symptoms of overstimulation:
Abdominal cramps, anxiety, changes in appetite, change in menstrual periods,
chest pain, diarrhea, emotional instability, fatigue, fever, flushing, hair
loss, headache, heart attack or failure, heat intolerance, hyperactivity,
increased heart rate, irregular heartbeat, irritability, muscle weakness,
nausea, nervousness, palpitations, shortness of breath, sleeplessness, sweating,
tremors, vomiting, weight loss
Why should Levothyroxine not be prescribed?
You should not be treated with Levothyroxine if you are hypersensitive
to thyroid hormone; your thyroid gland is making too much thyroid hormone;
you have had a recent heart attack; or your adrenal glands are not
making enough corticosteroid hormone. If you are sensitive to dyes,
you can take the Levothyroxine 50-microgram tablet, which is made without
color additives.
Although Levothyroxine will speed up your metabolism, it is not effective
as a weight-loss drug and should not be used as such. An overdose may
cause life-threatening side effects, especially if you take Levothyroxine
with an appetite-suppressant medication.
Special warnings about Levothyroxine
Levothyroxine has profound effects on the body. Make sure your doctor
is aware of all your medical problems, especially heart disease, clotting
disorders, diabetes, and disorders of the adrenal or pituitary glands.
The doctor will also need to know about any allergies you may have
to food or medicine, and will ask for the names of any medications
you take, whether prescription or over-the-counter.
You should receive low doses of Levothyroxine, under very close supervision,
if you are an older person, or if you suffer from high blood pressure,
angina (chest pain caused by a heart condition), or other types of
heart disease. If you develop chest pain or additional circulatory
problems, your dosage may have to be reduced.
If you have diabetes, or if your body makes insufficient adrenal corticosteroid
hormone, Levothyroxine will tend to make your symptoms worse. If you take
medication for any of these disorders, the dosage will probably have
to be adjusted once you begin taking Levothyroxine. If diabetes is the
problem, you should immediately report to your doctor any change in
your glucose readings.
Postmenopausal women on long-term Levothyroxine therapy may suffer a loss
of bone density, increasing the danger of osteoporosis (brittle bones).
To minimize the loss, the doctor will prescribe the lowest dosage needed
to control symptoms of thyroid deficiency.
Levothyroxine may cause seizures at the beginning of treatment, although
this is rare. You may also notice some hair loss at first, but this
is temporary.
It may take a few weeks for Levothyroxine to begin working, and you may
not see any change in your symptoms until then.
Tell your doctor or dentist you are taking Levothyroxine before you have
surgery of any kind.
Tell your doctor if you become pregnant while you are taking Levothyroxine.
Your dose may need to be increased.
Do not switch to another brand of levothyroxine without consulting
your doctor.
Excessive doses of Levothyroxine in infants may cause the top of the skull
to close too early. In children, overtreatment can stunt growth.
Possible food and drug interactions when taking Levothyroxine
Levothyroxine can interact with a wide variety of medications. It's advisable
to check with your doctor before taking any other drug, but you should
be especially wary of the following:
Amiodarone (Cordarone)
Androgens (male hormones)
Antacids and anti-gas medications
Antidepressants such as Elavil, Ludiomil, and Zoloft
Blood pressure drugs such as beta blockers, nitroprusside, and thiazide
diuretics
Blood-thinning drugs such as Coumadin and heparin
Chloral hydrate (a sedative)
Diabetes drugs such as insulin and Micronase
Digitalis-type drugs such as Lanoxin
Estrogen products and oral contraceptives
Furosemide (Lasix)
Growth hormones
Hormone inhibitors such as Cytadren and Tapazole
Iodide
Iron supplements
Kayexalate
Ketamine (Ketalar)
Lithium (Eskalith, Lithobid)
Methadone and heroin
Metoclopramide (Reglan)
Nonsteroidal anti-inflammatory drugs such as phenylbutazone and aspirin
Parkinson's drugs such as Sinemet
Propylthiouracil (a thyroid inhibitor)
Seizure medications such as Dilantin, Tegretol, and phenobarbital
Steroids such as dexamethasone and hydrocortisone
Stimulants such as epinephrine (EpiPen)
Sucralfate (Carafate)
The cancer drugs 5-fluorouracil, 6-mercaptopurine, mitotane, and tamoxifen
The cholesterol-lowering drugs Colestid, Mevacor, and Questran
The immune-system drugs interferon and interleukin
The tranquilizers Trilafon and Valium
The tuberculosis drugs aminosalicylate, rifampin, and ethionamide
Theophylline (Theo-Dur)
A high-fiber diet, soy-containing supplements, and walnuts can also
interfere with Levothyroxine effects.
Special information if you are pregnant or breastfeeding
If you need to take Levothyroxine because of a thyroid hormone deficiency,
you can continue to take Levothyroxine during pregnancy. In fact, your
doctor will test you regularly and may increase your dose. Once your
baby is born, you may breastfeed while continuing to take carefully
regulated doses of Levothyroxine.
Recommended dosage for Levothyroxine
Your doctor will tailor the dosage to meet your individual requirements,
taking into consideration the status of your thyroid gland and other
medical conditions you may have. Older adults often require somewhat
smaller doses. To make sure the dosage is right for you, the doctor
will monitor your thyroid hormone level with periodic blood tests.
Overdosage
An overdose of Levothyroxine can produce the same symptoms of overstimulation
listed under "Levothyroxine side effects" Confusion and disorientation
are also possible, and there have been reports of stroke, shock, coma,
and death. If you suspect a massive overdose, seek emergency medical
attention immediately.
