Synthroid
Generic Name: Levothyroxine
What is Synthroid?
Synthroid is a synthetic hormone prescribed when the thyroid gland is unable to make enough hormone. It is also used to treat or prevent the following: goiter (an enlarged thyroid gland); certain thyroid cancers; or thyroid hormone deficiency due to surgery, radiation, or certain drugs.What is the most important information I should know about Synthroid?
Although Synthroid may speed up your metabolism, it is not effective as a weight-loss drug and should not be used for this purpose. Too much Synthroid may cause severe--and possibly life-threatening--side effects, especially if you are also taking appetite suppressants.Call your doctor immediately if you experience any of the following side effects: rapid or irregular heartbeats, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleeplessness, tremors, change in appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, heat intolerance, fever, changes in menstrual periods, hives, or skin rash.
If you are taking Synthroid to make up for a lack of natural hormone, it is important to take it regularly at the same time every day. You will probably need to take it for the rest of your life.
Long-term Synthroid use has led to weaker bones, especially in postmenopausal women.
If you have heart disease, your doctor may need to start you on a lower dose to see how you respond to the medication.
Tell your doctor or dentist you are taking Synthroid before having any surgery.
Who should not take Synthroid?
Do not take Synthroid if you are sensitive to thyroid hormone; if your thyroid gland is overactive; if you have had a recent heart attack; or if your adrenal glands are not making enough hormone. If you are sensitive to dyes, you can take the Synthroid 50-microgram tablet, which is made without color additives.What should I tell my doctor before I take the first dose of Synthroid?
Tell your doctor about all prescription, over-the-counter, and herbal medications you are taking before beginning treatment with Synthroid. Also, talk to your doctor about your complete medical history, especially if you have a history of blood clots, anemia, angina (chest pain), diabetes, heart disease, high blood pressure, blood clotting disorders, problems with your pituitary or adrenal glands, seizures, or if you are pregnant, plan to become pregnant, or are breastfeeding.What is the usual dosage?
The information below is based on the dosage guidelines your doctor uses. Depending on your condition and medical history, your doctor may prescribe a different regimen. Do not change the dosage or stop taking your medication without your doctor's approval.Adults and Children: Your doctor will adjust the dose based on the condition being treated and your age and weight.
How should I take Synthroid?
Take Synthroid as a single dose, preferably on an empty stomach, 30 minutes to 1 hour before breakfast. The drug is absorbed better on an empty stomach.Certain foods and supplements can decrease the absorption of Synthroid. Do not take Synthroid within 4 hours of the following: walnuts, dietary fiber, antacids, and iron or calcium supplements.
Synthroid tablets may swell quickly, resulting in choking or gagging. Be sure to take the pills with an entire glass of water to avoid this problem.
If an infant or child cannot swallow whole tablets, you can crush the tablet and mix it into 1-2 teaspoonfuls of water. Have the child drink the mixture immediately; do NOT store it for later use. Soybean infant formula can decrease the absorption of Synthroid and should not be used for administering the crushed tablets.
What should I avoid while taking Synthroid?
Do not stop taking Synthroid or change the way you take it without your doctor's approval. Do not stop taking Synthroid even if you feel fine. Stopping the medicine could lead to other health problems, such as heart disease, problems during pregnancy, and infertility.What are possible food and drug interactions associated with Synthroid?
If Synthroid is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Synthroid with the following: amiodarone, androgens (male hormones), antacids and antigas medications, antidepressants such as imipramine and sertraline, blood pressure drugs, blood-thinners such as heparin and warfarin, cancer drugs (such as 5-fluorouracil, 6-mercaptopurine, mitotane, and tamoxifen), chloral hydrate, cholesterol-lowering drugs, diabetes drugs such as glyburide and insulin, digoxin, estrogen products and oral contraceptives, furosemide, growth hormones, hormone inhibitors such as aminoglutethimide and methimazole, interferon, interleukin, iodide/iodine, kayexalate, ketamine, lithium, methadone and heroin, metoclopramide, NSAIDs such as ibuprofen and naproxen, Parkinson's drugs such as levodopa/carbidopa, propylthiouracil, seizure medications (such as carbamazepine, phenobarbital, and phenytoin), steroids such as dexamethasone and hydrocortisone, stimulants such as epinephrine, sucralfate, tranquilizers, tuberculosis drugs, and theophylline.What are the possible side effects of Synthroid?
Side effects cannot be anticipated. If any develop or change in intensity, tell your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking this drug.Side effects may include: allergic reactions such as rash or hives, changes in appetite, initial and usually temporary hair loss, fatigue, headache, heat intolerance, diarrhea, vomiting, menstrual irregularities
Can I receive Synthroid if I am pregnant or breastfeeding?
If you need to take Synthroid because of a thyroid hormone deficiency, you can continue to take Synthroid during pregnancy, but your doctor will test you regularly and may change your dosage. Small amounts of thyroid hormone are excreted in breast milk; talk with your doctor if you plan on breastfeeding.What should I do if I miss a dose of Synthroid?
Take it as soon as you remember that day. If you do not remember until the next day, or if you miss more than one dose, call your doctor for advice.How should I store Synthroid?
Store at room temperature, away from light and moisture.
I'm Kristen Dore, PharmD. Welcome to PDR Health!
