Synthroid (Levothyroxine)

IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

Synthroid Online



COMMON BRAND NAME(S): Levothroid, Levoxyl, Synthroid, Unithroid

WARNING: This medication is not intended for use as a weight loss aid. Regular doses will not contribute to weight loss, and excessive doses can lead to severe, potentially life-threatening side effects, particularly when combined with diet pills.

USES: Levothyroxine is employed in the treatment of hypothyroidism, a condition where the thyroid is underactive. It either substitutes or supplements the thyroid hormone that is usually generated by the thyroid gland. A deficiency in thyroid hormone can occur naturally, or it can be caused by damage to the thyroid gland due to radiation or medications, or surgical removal of the gland. Adequate levels of thyroid hormone are crucial for sustaining normal cognitive and physical functions. In the case of children, sufficient thyroid hormone is vital for their normal mental and physical growth.

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.

HOW TO USE: Take this medication orally, as directed by your healthcare provider, typically once a day on an empty stomach, 30 minutes to 1 hour prior to breakfast. Unless otherwise instructed by your doctor, drink a full glass of water when taking this medication.

If you're consuming the capsule version of this medication, swallow it intact. Do not split, crush, or chew it. Those unable to swallow the capsule (like infants or young children) should use the tablet form.

For infants or children unable to swallow tablets whole, crush the tablet and blend it in 1 to 2 teaspoons (5 to 10 milliliters) of water. Then, using a spoon or dropper, administer it immediately. Do not prepare a batch in advance or mix the tablet with soy-based infant formula. For additional information, consult your pharmacist.

The dosage depends on factors such as your age, weight, health status, laboratory test outcomes, and response to therapy.

To gain maximum benefit from this medication, use it consistently. A helpful tip is to take it at the same time daily.

Never discontinue this medication without first discussing it with your doctor. Thyroid replacement therapy is typically lifelong.

There are various brands of levothyroxine in the market. Do not switch brands without first consulting your doctor or pharmacist.

Certain drugs (including cholestyramine, colestipol, colesevelam, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium carbonate, orlistat) can reduce your body's absorption of thyroid hormone. If you're taking any of these drugs, take them at least 4 hours apart from this medication.

Signs of low thyroid hormone levels encompass fatigue, muscle pain, constipation, dry skin, weight gain, slow heartbeat, or cold sensitivity. If your condition does not improve or if it deteriorates after several weeks of using this medication, inform your doctor.

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 immediately 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.

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.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

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.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

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.

DRUG INTERACTIONS: See also How to Use Section.

The effects of certain drugs may be altered if you concurrently consume other medications or herbal products. This could elevate your chances of experiencing serious side effects or may cause your medications to not work as expected. These drug interactions are a possibility, but don't necessarily happen. By adjusting the way you use your medications in collaboration with your doctor or pharmacist can frequently prevent or manage interactions.

To ensure your doctor and pharmacist provide optimal care, make sure you inform them about all products you use (including prescription and nonprescription drugs, and herbal products) prior to initiating treatment with this product. While on this product, do not start, stop, or adjust the dosage of any other medications without your doctor's consent.

Products that may interact with this drug include: anticoagulants such as warfarin, digoxin, diabetes medications like insulin, sulfonylureas including glipizide, products containing estrogen (including birth control pills), and theophylline.

This document does not list all possible drug interactions. Keep a record of all the products you use and share it with your doctor and pharmacist to reduce your risk of serious medication issues.

OVERDOSE: If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: fast/pounding/irregular heartbeat, loss of consciousness, confusion, seizures.

NOTES: Do not share this medication with others.

Laboratory and/or medical tests (such as thyroid function tests) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

MISSED DOSE: In case you forget a dose, administer it as soon as you recall. However, if it's nearly time for your subsequent dose, bypass the forgotten dose and continue with your regular dosage regimen. Unless instructed by your doctor, do not take an extra dose to make up for the missed one. If you overlook 2 or more consecutive doses, contact your doctor. You should discuss with your doctor beforehand about the procedure for handling missed doses and abide by their particular instructions.

STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Information last revised June 2010 Copyright(c) 2010 First DataBank, Inc.