Levothyroxine-oral

See also Precautions section.

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.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

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

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).

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.