Synthroid Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing

Uses

Levothyroxine is used to treat an underactive thyroid (hypothyroidism). It replaces or provides more thyroid hormone, which is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. Having enough thyroid hormone is important for maintaining normal mental and physical activity. In children, having enough thyroid hormone is important for normal mental and physical development.This medication is also used to treat other types of thyroid disorders (such as thyroid cancer).This medication should not be used to treat infertility unless it is caused by low thyroid hormone levels.

How to use Synthroid

Read the Patient Information Leaflet if available from your pharmacist before you start taking levothyroxine and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually once daily on an empty stomach, 30 minutes to 1 hour before breakfast. Take this medication with a full glass of water unless your doctor directs you otherwise.

If you are taking the capsule form of this medication, swallow it whole. Do not split, crush, or chew. People who cannot swallow the capsule whole (such as infants or small children) should use the tablet form of the medication.

For infants or children who cannot swallow whole tablets, crush the tablet and mix in 1 to 2 teaspoons (5 to 10 milliliters) of water, and give using a spoon or dropper right away. Do not prepare a supply in advance or mix the tablet in soy infant formula. Consult your pharmacist for more information.

The dosage is based on your age, weight, medical condition, lab test results, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day.

Do not stop taking this medication without first consulting with your doctor. Thyroid replacement treatment is usually taken for life.

There are different brands of levothyroxine available. Do not change brands without first consulting your doctor or pharmacist.

Certain medications (such as cholestyramine, colestipol, colesevelam, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium supplements, orlistat, sucroferric oxyhydroxide, lanthanum, sevelamer, among others) can decrease the amount of thyroid hormone that is absorbed by your body. If you are taking any of these drugs, separate them from this medication by at least 4 hours.

Symptoms of low thyroid hormone levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold. Tell your doctor if your condition gets worse or lasts after several weeks of taking this medication.

Graves' Disease

Side Effects

Warnings

This medication should not be used for weight loss. Normal doses of this medication will not work for weight loss, and large doses of this medication may cause serious, possibly fatal side effects, especially when taken with diet pills.

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.

If you have diabetes, this drug may affect your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms such as increased thirst/urination, shakiness, unusual sweating, dizziness, or hunger. Your doctor may need to adjust your diabetes medication, exercise program, or diet.

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.

This drug may be used during pregnancy. Tell your doctor if you are pregnant because your doctor may need to change your dose.

Levothyroxine passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.

Interactions

Overdose

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: fast/pounding/irregular heartbeat, loss of consciousness, confusion, seizures.

Notes

Do not share this medication with others.

Lab and/or medical tests (such as thyroid function) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up unless your doctor tells you to do so. Call your doctor if you miss 2 or more doses in a row. Ask your doctor ahead of time what to do about a missed dose and follow your doctor's specific directions.

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.