Levothyroxine Sodium

💊 What is Levothyroxine Sodium used for?

• •Hypothyroidism (an underactive thyroid), as replacement therapy in adults and children, including newborns, whether caused by the thyroid, the pituitary gland, or the hypothalamus
• •Pituitary TSH suppression, as an add-on to surgery and radioiodine therapy for certain thyroid cancers (thyrotropin-dependent well-differentiated thyroid cancer)

How it works

The label says the levothyroxine in this tablet is meant to replace a hormone that the thyroid gland normally produces. The label also notes that it may take several weeks before symptoms improve, and that peak effect may not be reached for 4 to 6 weeks.

How it is usually taken

• •The label says it is taken once a day, preferably on an empty stomach, one-half to one hour before breakfast, with a full glass of water.
• •The label says to take it as a single dose to avoid choking or gagging.
• •The label says to take it at least 4 hours apart from certain drugs and supplements that can reduce how well it is absorbed.
• •The label says that for children who cannot swallow whole tablets, the tablet can be crushed and mixed into a small amount of water and given right away. Ask your pharmacist or prescriber before doing this.

Comes as

• •Tablets in 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, and 300 mcg strengths
• •Each strength is a different color, and all tablets are scored with a break line so they can be split

⚠️ Levothyroxine Sodium side effects

🛑 Who should not take Levothyroxine Sodium, and who should be careful

The label says not to take it if

• 🚨You have uncorrected adrenal insufficiency. The label lists this as a contraindication.
• 🚨The label says this medicine should not be used for obesity or weight loss.
• 🚨The label says oral thyroid hormone products are not recommended to treat myxedema coma (a life-threatening emergency), and that intravenous products are used instead.

Tell your doctor before taking it if

• •Tell your doctor if you have heart disease, a history of angina or irregular heart rhythm, since the label says the dose may need to be started lower in older adults and people with heart disease.
• •Tell your doctor if you have diabetes. The label says this medicine may change blood sugar control and blood sugar should be watched closely.
• •Tell your doctor if you have a clotting disorder or take anticoagulants, since the label says clotting status should be checked often in people on anticoagulants.
• •Tell your doctor about adrenal or pituitary gland problems, because other medicines may need adjusting.
• •Tell your doctor if you are pregnant, breastfeeding, or thinking of becoming pregnant.
• •Tell your doctor or dentist that you take this medicine before any surgery.
• •The label says to stop biotin and any biotin-containing supplements at least 2 days before thyroid blood tests.

🔀 Levothyroxine Sodium with other medicines, food and alcohol

The label says to discuss these with your doctor or pharmacist

• •Iron, calcium supplements, antacids, phosphate binders (such as calcium carbonate, sevelamer, or lanthanum), bile acid sequestrants (such as colesevelam or cholestyramine), and sucralfate can reduce absorption. The label says to take this medicine at least 4 hours apart from these.
• •Proton pump inhibitors may reduce absorption, according to the label.
• •Orlistat may affect thyroid function, and the label says monitoring is needed.
• •Estrogen-containing oral contraceptives, oral estrogens, and tamoxifen can change thyroid hormone binding in the blood, according to the label.
• •Androgens, anabolic steroids, and glucocorticoids can also change thyroid hormone levels in the blood, according to the label.
• •Sympathomimetic amines (such as some appetite suppressants) can cause serious toxicity at higher thyroid hormone doses, according to the boxed warning.
• •Anticoagulants: the label says clotting status should be checked frequently.
• •Diabetes medicines and insulin may need adjusting, since this medicine can change blood sugar control.
• •Tell your prescriber or pharmacist about all prescription and over-the-counter medicines and supplements you take.

Alcohol and food

The label says this medicine is best taken on an empty stomach, one-half to one hour before breakfast. The label says the dose may need review if it is regularly taken within one hour of certain foods that affect absorption. The label gives soybean-based infant formula as an example of food that decreases absorption. The label does not discuss alcohol.

🤰 Levothyroxine Sodium in pregnancy and breastfeeding

Pregnancy

The label says pregnant women treated with oral levothyroxine to maintain normal thyroid function have not shown increased rates of major birth defects, miscarriage, or other adverse outcomes in clinical experience. The label says untreated hypothyroidism in pregnancy carries risks to the mother and baby. TSH levels may rise during pregnancy, so TSH should be monitored and the dose adjusted. The label says this medicine should not be stopped during pregnancy. Tell your prescriber right away if you are pregnant or planning to become pregnant.

Breastfeeding

The label says levothyroxine is present in human milk. No adverse effects on breastfed infants have been reported. The label says the benefits of breastfeeding should be weighed along with the mother's need for levothyroxine. Talk with your prescriber about breastfeeding.

🗓️ Storage, missed doses and taking too much

Storage

The label does not say.

If a dose is missed

The label does not say.

If too much is taken

The label says the signs of overdose are the same as those of too much thyroid hormone (hyperthyroidism). Confusion and disorientation may also occur. Serious outcomes, including seizures, shock, coma, and death, have been reported. Symptoms may not appear until several days after taking the medicine. If you think someone has taken too much, contact the National Poison Control Center at 1-800-222-1222 or www.poison.org, or get emergency medical help right away.

🗒️ Questions to ask about Levothyroxine Sodium

• How long will it take before I notice that my symptoms are getting better?
• What is the best time of day for me to take this tablet, and how far apart should I take it from my iron, calcium, or antacids?
• Do any of my other medicines or supplements interact with levothyroxine?
• How often will I need thyroid blood tests, and do I need to stop biotin before them?
• What should I do if I am pregnant, planning a pregnancy, or breastfeeding?
• Could this medicine affect my blood sugar, heart rhythm, or bones over time?
• What should I do if I miss a dose?

❓ Levothyroxine Sodium: frequently asked questions