Synthroid is used for treating low thyroid hormone levels and certain types of goiters. It is also used with surgery and other medicines for managing certain types of thyroid cancer. Synthroid is a thyroid hormone. It works by replacing thyroid hormone when your body does not make enough on its own.
Use Synthroid as directed by your doctor.
- Take Synthroid by mouth on an empty stomach at least one-half to one hour before breakfast.
- Do not take an antacid or a product that has iron or calcium in it within 4 hours of taking Synthroid.
- If the patient is a child or if you cannot swallow the tablet whole, you may crush the correct dose of the medicine. Add the crushed medicine to 1 to 2 teaspoons (5 to 10 mL) of water. Mix well. Use a spoon or dropper to give the medicine as soon as possible. Do not store the mixture for later use. Do not mix crushed tablets in soybean infant formula. Ask your pharmacist if you have any questions.
- Synthroid works best if it is taken at the same time each day.
- Continue to take Synthroid even if you feel well. Do not miss any dose.
- It may take several weeks before you notice an improvement in your symptoms. Do not stop or change your dose of Synthroid without first checking with your doctor.
- If you miss a dose of Synthroid, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use Synthroid.
Store Synthroid between 68 and 77 degrees F (20 and 25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Protect from heat, light, and moisture. Do not store in the bathroom. Keep Synthroid out of the reach of children and away from pets.
Active Ingredient: Levothyroxine sodium.
Do NOT use Synthroid if:
- you are allergic to any ingredient in Synthroid
- you have untreated adrenal gland problems or high thyroid hormone levels
- you have had a recent heart attack.
Contact your doctor or health care provider right away if any of these apply to you.
Some medical conditions may interact with Synthroid. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have trouble swallowing, heart or blood vessel problems (eg, coronary artery disease), high blood pressure, blood clotting or bleeding problems, pernicious anemia, diabetes, bone problems (eg, osteoporosis), fertility problems, pituitary problems, adrenal gland problems, or other thyroid problems
- if you have problems absorbing nutrition from your stomach or intestines into your body
- if you had a recent surgery or have an upcoming surgery.
Some medicines may interact with Synthroid. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Many prescription and nonprescription medicines (eg, used for infections, inflammation, aches and pains, nasal congestion, asthma, high blood pressure, irregular heartbeat or other heart problems, blood thinning, mental or mood problems, depression, diabetes, other thyroid problems, high cholesterol, hepatitis, weight loss, heartburn, birth control, hormone replacement therapy, growth hormone deficiency, cancer, seizures), and multivitamin products may interact with Synthroid, increasing the risk of side effects or decreasing effectiveness.
This may not be a complete list of all interactions that may occur. Ask your health care provider if Synthroid may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
Important safety information:
- It is important to take Synthroid exactly as prescribed. Do not take more than the prescribed dose without checking with your doctor.
- Tell your doctor or dentist that you take Synthroid before you receive any medical or dental care, emergency care, or surgery.
- Diabetes patients - Synthroid may affect your blood sugar. Check blood sugar levels closely. Ask your doctor before you change the dose of your diabetes medicine.
- Foods that contain soybean flour (including infant formula), cottonseed meal, walnuts, or dietary fiber may decrease the absorption of Synthroid. Tell your doctor if your diet includes any of these foods. Your doctor may need to change your dose of Synthroid.
- Mild hair loss may rarely occur during the first few months of treatment with Synthroid. This is usually temporary. Contact your doctor if hair loss is severe or persistent.
- Lab tests, including thyroid hormone level and growth checks, may be performed while you use Synthroid. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
- Use Synthroid with caution in the elderly; they may be more sensitive to its effects, especially heart problems.
- Children and teenagers may need regular growth checks while they take Synthroid.
- Pregnancy and breast-feeding: If you become pregnant, contact your doctor. Your doctor may need to change your dose of Synthroid. Synthroid is found in breast milk. If you are or will be breast-feeding while you use Synthroid, check with your doctor. Discuss any possible risks to your baby.
All medicines may cause side effects, but many people have no, or minor, side effects.
No common side effects have been reported with the use of Synthroid.
Seek medical attention right away if any of these severe side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; flushing; tightness in the chest; swelling of the mouth, face, lips, or tongue; unusual hoarseness); changes in appetite; changes in menstrual periods; chest pain; diarrhea; excessive sweating; fast or irregular heartbeat; fever; heat intolerance; joint pain; leg cramps; mental or mood changes (eg, anxiety, irritability, nervousness); muscle weakness; seizures; severe or persistent headache or fatigue; shortness of breath; stomach cramps; tremors; trouble sleeping; unusual weight gain or weight loss; vomiting; wheezing.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.