What is levothyroxine?

Levothyroxine is used in adults and children to treat hypothyroidism (underactive thyroid – a condition where the thyroid gland does not produce enough thyroid hormone).

Levothyroxine is also used in adults along with surgery and radioactive iodine therapy to treat a certain type of thyroid cancer.

Levothyroxine injection is used in adults to treat myxedema coma.

Levothyroxine belongs to a class of medications called hormones. It works by replacing thyroid hormone that is normally produced by the body.

Without thyroid hormone, your body cannot function properly, which may result in poor growth, slow speech, lack of energy, excessive tiredness, constipation, weight gain, hair loss, dry, thick skin, increased sensitivity to cold, joint and muscle pain, heavy or irregular menstrual periods, and depression. When taken correctly, levothyroxine reverses these symptoms.

Levothyroxine side effects

Get emergency medical help if you have signs of an allergic reaction to levothyroxine: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Levothyroxine may cause serious side effects. Call your doctor at once if you have:

• sudden pain or trouble moving your hip, wrist, or back;
• fast or irregular heartbeats;
• chest pain, pain spreading to your jaw or shoulder;
• wheezing;
• fever, swollen glands, itching, joint pain, or not feeling well;
• nausea, vomiting, or diarrhea; or
• high blood sugar – increased thirst, increased urination, dry mouth, fruity breath odor.

Common levothyroxine side effects may include:

• fever, hot flashes, increased sweating;
• tiredness;
• skin rash, hair loss;
• chest pain, fast or irregular heartbeats, shortness of breath;
• headache, leg cramps, muscle pain or weakness;
• tremors, feeling nervous or irritable, sleep problems (insomnia);
• increased or change in appetite;
• weight loss or weight gain;
• changes in your menstrual periods; or
• vomiting, diarrhea.

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 .

Warnings

You may not be able to use levothyroxine if you have certain medical conditions. Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder or any heart problems such as a recent heart attack.

Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of this medicine, especially if you are taking any other weight-loss medications or appetite suppressants.

Taking more than your recommended dose will not make this medicine more effective, and may cause serious side effects.

Before taking this medicine

You should not use levothyroxine if you are allergic to glycerin or edetate disodium, or if you have an untreated or uncontrolled adrenal gland disorder.

To make sure this medicine is safe for you, tell your doctor if you have ever had:

• a thyroid nodule;
• thyroiditis (inflammation of thyroid gland);
• heart problems such as a heart attack, stroke;
• a blood clot or a blood clotting disorder;
• diabetes (your diabetes medicine may need to be adjusted);
• anemia (low red blood cells);
• weak bones (osteoporosis), or low bone mineral density;
• problems with your pituitary or adrenal gland;
• an allergy to any food or drugs;
• recently received radiation therapy with iodine (such as I-131); or
• kidney disease.

Tell your doctor if you are pregnant or plan to become pregnant. Having hypothyroidism during pregnancy may increase the risk of premature birth or other complications. The benefit of treating hypothyroidism may outweigh any risks to the 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.

You may be more likely to have a broken bone while using levothyroxine. Talk with your doctor about ways to keep your bones healthy.

How should I use levothyroxine?

Take levothyroxine exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Some brands of levothyroxine have different dosage instructions and/or recommendations of how soon you need to take them before eating food. Always check the instructions on the label.

Oral levothyroxine

Oral levothyroxine is taken by mouth and is available as tablets, capsules, and an oral solution.

• Keep using this medicine even if you feel well. You may not fully benefit from this medicine for several weeks.
• You will need frequent medical tests, and your next dose may be delayed based on the results.
• This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using this medicine.
• Tell your doctor if you have a planned surgery or dental procedure.
• Taking more than your recommended dose will not make this medicine more effective, and may cause serious side effects.

Tablets and capsules

Take levothyroxine tablets and capsules on an empty stomach, at least 30 to 60 minutes before breakfast with a full glass of water. Take the medicine at the same time each day.

• Swallow the capsule whole and do not crush, chew, break, or open it. Tell your doctor if your child cannot swallow a capsule whole.
• If you cannot swallow a tablet whole, crush the tablet, and mix it with 1 or 2 teaspoons of water; give the mixture right away. Do not save it for later use.
• Keep each tablet or capsule in the blister pack until you are ready to take one.
• Store at room temperature away from moisture, heat, and light.

Oral solution (liquid medicine)

Measure liquid medicine with the supplied measuring device (not a kitchen spoon).

• Dosages are based on weight in children and teenagers. Your child’s dose may change if the child gains or loses weight.
• Your dose needs may change if you switch to a different brand, strength, or form of levothyroxine. Avoid medication errors by using only the medicine your doctor prescribes.
• Tirosint-Sol oral solution can be administered 15 minutes before eating breakfast. Use it within 3 months after opening the pouch.
• Ermeza and Thyquidity liquids should be taken on an empty stomach, at least 30 to 60 minutes before breakfast. Store them in their original bottle. Use Ermeza within 90 days and Thyquidity within 8 weeks of opening the bottle.
• Store at room temperature away from moisture, heat, and light.

Intravenous levothyroxine

This is given as an injection into a vein by a healthcare provider and should only be used to treat myxedema coma.

What happens if I miss a dose?

In a medical setting, you are not likely to miss a dose of levothyroxine injection.

Take the missed oral levothyroxine dose as soon as you remember, and then go back to your regular schedule. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line . An overdose can be fatal.

Overdose symptoms may include headache, leg cramps, tremors, feeling nervous or irritable, chest pain, shortness of breath, fast or pounding heartbeats, stroke, and coma.

What should I avoid while using levothyroxine?

Avoid the following food products within 1 hour of taking oral levothyroxine or the medication will not be as effective: grapefruit juice, infant soy formula, soybean flour, cotton seed meal, walnuts, and high-fiber foods.

What is desiccated thyroid?

Desiccated (dried) thyroid is a combination of hormones that are normally produced by your thyroid gland to regulate the body’s energy and metabolism. Desiccated thyroid is given when the thyroid does not produce enough of this hormone on its own.

Desiccated thyroid treats hypothyroidism (low thyroid hormone). Desiccated thyroid is also used to treat or prevent goiter (enlarged thyroid gland), and is also given as part of a medical tests for thyroid disorders.

Desiccated thyroid should not be used to treat obesity or weight problems.

Desiccated thyroid may also be used for purposes not listed in this medication guide.

Desiccated thyroid side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Common side effects may include temporary hair loss (especially in children).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

Warnings

You may not be able to use NP Thyroid if you have a thyroid disorder called thyrotoxicosis, or an adrenal gland problem that is not controlled by treatment.

Call your doctor if you have signs of thyroid toxicity, such as chest pain, fast or pounding heartbeats, feeling hot or nervous, or sweating more than usual.

Before taking this medicine

Since thyroid hormone occurs naturally in the body, almost anyone can take desiccated thyroid. However, you may not be able to use this medication if you have a thyroid disorder called thyrotoxicosis, or an adrenal gland problem that is not controlled by treatment.

To make sure desiccated thyroid is safe for you, tell your doctor if you have:

• heart disease, angina (chest pain);
• coronary artery disease;
• congestive heart failure;
• any type of diabetes; or
• problems with your adrenal gland.

Desiccated thyroid is not expected to be harmful to an unborn baby, but your dose needs may be different during pregnancy. Tell your doctor if you become pregnant while taking this medicine.

Small amounts of desiccated thyroid can pass into breast milk, but this is not expected to harm a nursing baby. However, do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take desiccated thyroid?

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use NP Thyroid in larger or smaller amounts or for longer than recommended.

While using desiccated thyroid, you may need frequent blood tests.

Keep using this medicine as directed, even if you feel well. You may need to take thyroid medication for the rest of your life.

Call your doctor if you notice any signs of thyroid toxicity, such as chest pain, fast or pounding heartbeats, feeling hot or nervous, or sweating more than usual.

If you need surgery, tell the surgeon ahead of time that you are using desiccated thyroid. You may need to stop using the medicine for a short time.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line .

What should I avoid while taking desiccated thyroid?

If you also take cholestyramine (Prevalite, Questran) or colestipol (Colestid), avoid taking these medications within 4 hours before or after you take desiccated thyroid.

Avoid taking an antacid within 4 hours before or after you take desiccated thyroid. Some antacids can make it harder for your body to absorb desiccated thyroid.

What other drugs will affect desiccated thyroid?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with desiccated thyroid, especially:

• birth control pills or hormone replacement therapy;
• a blood thinner such as warfarin, Coumadin, Jantoven;
• insulin or diabetes medication you take by mouth;
• medications that contain iodine (such as I-131);
• salicylates such as aspirin, Nuprin Backache Caplet, Kaopectate, KneeRelief, Pamprin Cramp Formula, Pepto-Bismol, Tricosal, Trilisate; or
• steroids such as prednisone and others.