Levothyroxine (Synthroid)
Levothyroxine is a medicine used to treat people with hypothyroidism.
Hypothyroidism means a person’s thyroid gland doesn’t make enough thyroid hormone. People with this condition may no longer have a functioning thyroid, or hypothyroidism can be caused by a variety of other reasons that affect thyroid hormone production.
Levothyroxine is also used to prevent or treat a goiter (an enlarged thyroid gland) or with other therapies to treat thyroid cancer.
This drug is a hormone, which works by replacing thyroid hormone that your body normally produces.
The U.S. Food and Drug Administration (FDA) initially approved this medicine in 1969. It’s marketed under various brands.
uses
What isLevothyroxine (Synthroid)used for?
- Hypothyroidism
- Myxedema Coma
- TSH Suppression
warnings
What is the most important information I should know aboutLevothyroxine (Synthroid)?
Levothyroxine should not be used to treat obesity or weight problems.Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants.
Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However,you may not be able to take this medicine if you have certain medical conditions.Tell your doctor if you have:
- an untreated or uncontrolled adrenal gland disorder;
- a thyroid disorder called thyrotoxicosis; or
- symptoms of a heart attack (chest pain or heavy feeling, pain spreading to the jaw or shoulder, nausea, sweating, general ill feeling).
Tell your doctor if you have ever had:
- a thyroid nodule;
- 心脏病,一个提单ood clot, or a blood-clotting disorder;
- diabetes (insulin or oral diabetes medication doses may need to be changed when you start taking levothyroxine);
- kidney disease;
- anemia (lack of red blood cells);
- osteoporosis, or low bone mineral density;
- problems with your pituitary gland; or
- any food or drug allergies.
Tell your doctor if you have recently received radiation therapy with iodine (such as I-131).
If you become pregnant while taking levothyroxine, do not stop taking the medicine without your doctor's advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby.Your dose needs may be different during pregnancy.
Tell your doctor if you are breastfeeding.Your dose needs may be different while you are nursing.
Do not give this medicine to a child without medical advice.Tirosintis not approved for use by anyone younger than 6 years old.
User Reviews & Rating
Overall rating forLevothyroxine (Synthroid)
Side Effects
What are the side effects ofLevothyroxine (Synthroid)?
Get emergency medical help if you havesigns of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
马上打电话给你的医生如果你有:
- fast or irregular heartbeats;
- chest pain, pain spreading to your jaw or shoulder;
- shortness of breath;
- fever, hot flashes, sweating;
- tremors, or if you feel unusually cold;
- weakness, tiredness, sleep problems (insomnia);
- memory problems, feeling depressed or irritable;
- headache, leg cramps, muscle aches;
- feeling nervous or irritable;
- dryness of your skin or hair, hair loss;
- irregular menstrual periods; or
- vomiting, diarrhea, appetite changes, weight changes.
Certain side effects may be more likely in older adults.
Common side effects may include:
- chest pain, irregular heartbeats;
- shortness of breath;
- headache, leg cramps, muscle pain or weakness;
- tremors, feeling nervous or irritable, trouble sleeping;
- increased appetite;
- feeling hot;
- weight loss;
- changes in your menstrual periods;
- diarrhea; or
- skin rash, partial hair loss.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Pregnancy & Breastfeeding
Can I takeLevothyroxine (Synthroid)if I’m pregnant or breastfeeding?
If you become pregnant while taking levothyroxine, do not stop taking the medicine without your doctor's advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby.Your dose needs may be different during pregnancy.
Tell your doctor if you are breastfeeding.Your dose needs may be different while you are nursing.
Interactions
What drugs and food should I avoid while takingLevothyroxine (Synthroid)?
Avoid the following food products, which can make your body absorb less levothyroxine:grapefruit juice, infant soy formula, soybean flour, cotton seed meal, walnuts, and high-fiber foods.
Dosage Guidelines & Tips
How to takeLevothyroxine (Synthroid)?
UseLevothyroxine (Synthroid)exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.
Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.
Levothyroxineoralis taken by mouth. Levothyroxineinjectionis given as an infusion into a vein. Levothyroxine is usually given by injection only if you are unable to take the medicine by mouth.
Levothyroxineoralworks best if you take it on an empty stomach, 30 to 60 minutes before breakfast. Follow your doctor's dosing instructions and try to take the medicine at the same time each day.
Swallow thetabletorcapsulewhole, with a full glass (8 ounces) of water. The levothyroxine tablet may dissolve very quickly and could swell in your throat.
Measureliquid medicinecarefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).
左旋甲状腺素剂量是根据重量的孩子们n. Your child's dose needs may change if the child gains or loses weight.
It may take several weeks before your body starts to respond to levothyroxine.Keep using this medicine even if you feel well.You may need to use levothyroxine for the rest of your life.
You may need frequent medical tests.Tell any doctor, dentist, or surgeon who treats you that you are using levothyroxine.
Store at room temperature away from moisture and heat.
Do not share this medicine with another person, even if they have the same symptoms you have.
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose.Do nottake two doses at one time.
Overdose Signs
What happens if I overdose onLevothyroxine (Synthroid)?
Overdose symptoms may include headache, leg cramps, tremors, feeling nervous or irritable, chest pain, shortness of breath, and fast or pounding heartbeats.
What to Expect
Levothyroxine starts working right away, but it may take several weeks before you notice that your symptoms improve.
Usually, treatment with levothyroxine is lifelong. If you stop taking it, your symptoms will return.Additional Dosage Information
Your dosage will depend on your age, your medical condition, and other factors.
Your physician may need to adjust your dosage if you’re pregnant or if you have heart problems. They may also need to periodically change your dose on the basis of your blood tests.
Most of the time, side effects occur because you’re taking a larger dose than you need. If you experience side effects, your doctor can lower your dose.
Secondary Uses
Levothyroxine is sometimes used as an “off-label” treatment for subclinical hypothyroidism — a mild, but very common, form of hypothyroidism.
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