Common uses

Levothyroxine is used to treat an underactive thyroid (hypothyroidism). It replaces the hormone that is normally produced by the thyroid gland. Low thyroid levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. It is important to have adequate levels of thyroid hormone in your bloodstream to maintain normal mental and physical activity. In children, adequate levels of thyroid hormone are important for normal mental and physical growth and development.
This medication is used to treat other types of thyroid disorders as well (e.g., certain types of goiters, thyroid nodules, thyroiditis, thyroid cancer).

Before using

Before taking levothyroxine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: overactive thyroid conditions (e.g., thyrotoxicosis), a heart attack (acute myocardial infarction), adrenal gland problems (e.g., uncorrected adrenal insufficiency).
Do not use thyroid drugs for weight control.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (e.g., hypertension, congestive heart failure, arrhythmias, coronary artery disease), diabetes, male or female infertility problems (unless caused by underactive thyroid disease), bone loss disease (e.g., osteoporosis), other hormone disorders (e.g., hypothalamic/pituitary hormone deficiencies, autoimmune polyglandular syndrome), certain thyroid problems (e.g., nontoxic diffuse goiter, nodular thyroid disease), blood clotting disorders.
Notify your doctor or dentist that you are taking this medication prior to any surgery.
Caution is advised when using this drug in children because overuse may reduce the child's future adult height. Consult your doctor for details.
Caution is advised when using this drug in the elderly because they may be more sensitive to the effects of the drug.
Current information shows that this drug may be used during pregnancy. Tell your doctor if you are pregnant because your dose will have to be adjusted.
Small amounts of this drug pass into breast milk. Consult your doctor before breast-feeding.

Directions

Follow the directions for taking this medicine provided by your doctor. Take this medicine on an empty stomach at least 1/2 to 1 hour before breakfast unless otherwise directed by your doctor. TAKE THIS MEDICINE WITH A FULL GLASS OF WATER to reduce the risk of choking, gagging, or trouble swallowing when taking this medicine. FOR CHILDREN WHO CANNOT SWALLOW WHOLE TABLETS, crush the tablet and mix in 1 or 2 teaspoons (5 or 10 ml) of water, and give using a spoon or dropper as soon as possible after preparation. Do not store the mixture for later use. Do not mix crushed tablets in soybean infant formula. Consult your pharmacist for more information. Some medicines such as aluminum, calcium, or magnesium-containing antacids; simethicone; calcium supplements; iron; cholestyramine; colestipol; sucralfate; or sodium polystyrene sulfonate may decrease the absorption of this medicine into your bloodstream. Take this medicine at least 4 hours apart from these medicines. STORE THIS MEDICINE at room temperature in a tightly-closed container, away from heat, moisture, and light. Take this medicine regularly to receive the most benefit from it. Taking this medicine at the same time each day will help you to remember. CONTINUE TO TAKE THIS MEDICINE even if you feel well. Do not miss any doses. IF YOU MISS A DOSE OF THIS MEDICINE, take the missed dose if you remember the same day. Skip the missed dose if you do not remember until the next day and go back to your regular dosing schedule. DO NOT take 2 doses at once.

Cautions

This medication should not be used either alone or in combination with diet pills to treat obesity or for weight loss because serious, even life-threatening, effects could occur. Large doses of this medication, especially with diet pills, may cause symptoms of toxicity.

Possible side effects

A SIDE EFFECT that may occur while taking this medicine is, in rare instances, some hair loss within the first few months of starting this medicine. This effect is usually temporary as your body adjusts to this medicine. If this effect persists or worsens, notify your doctor as soon as possible. CHECK WITH YOUR DOCTOR AS SOON AS POSSIBLE if you experience headache, nervousness, vomiting, diarrhea, irritability, trouble sleeping, changes in menstrual periods, leg cramps, trembling, excessive sweating, fever, sensitivity to heat, or unexplained changes in weight or appetite. CONTACT YOUR DOCTOR IMMEDIATELY if you experience chest pain, rapid or irregular heartbeat, or seizures. An allergic reaction to this medicine is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include rash, itching, swelling, dizziness, or trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.

If you take too much

If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include extreme nervousness, confusion, excessive sweating, irregular heartbeat, chest pain, and seizures.

Additional information

It is recommended that levothyroxine be taken half an hour to an hour before meals to maximize its absorption. It is also recommended that the patient take the tablet with one glass of water to ease swallowing as well as to help the tablet dissolve for absorption.

Drug interactions

The following drugs may cause medical problems if you use them with Levoxyl: lithium, amiodarone, or antidepressants. Tell your doctor if you have recently received radiation therapy with iodine (such as I-131).
There are many other drugs not listed that can affect Levoxyl. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.
Certain medicines can be continued, but they may make Levoxyl less effective if taken at the same time. If you use any of the following drugs, use them at least 4 hours before or 4 hours after you take Levoxyl:
• calcium carbonate (Caltrate, Citracal, Oystercal, and others);
• ferrous sulfate iron supplement;
• sucralfate (Carafate);
• sodium polystyrene sulfonate (Kayexalate, Kionex, and others);
• antacids that contain aluminum (Amphojel, Gaviscon, Maalox, Mylanta, Riopan, Rulox, Tums, and others); and
• cholesterol-lowering drugs cholestyramine (Questran) and colestipol (Colestid).