Levothyroxine, Oral

What are other names for this medicine?

Type of medicine: thyroid hormone

Generic and brand names: levothyroxine, oral; Levo-T; Levothroid; Levoxyl; Novothyrox; Synthroid; Unithroid

What is this medicine used for?

This medicine is taken by mouth to treat hypothyroidism (when your body does not produce enough thyroid hormone). It may also be used to treat goiter and thyroid cancer.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have:

• an allergy to any medicine
• adrenal or pituitary gland problems
• diabetes
• heart disease or a heart attack
• high blood pressure
• osteoporosis
• problems with blood clotting
• trouble swallowing

Females of childbearing age: Tell your healthcare provider if you are pregnant, plan to become pregnant, or are breast-feeding. Do not breast-feed while taking this medicine without your healthcare provider's approval.

How do I take it?

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as directed by your healthcare provider. Do not take more or less of it or take it longer than prescribed. Do not stop taking this medicine without your healthcare provider's approval.

It is best to take this medicine on an empty stomach, 30 minutes before you eat or 2 hours after you eat. Do not take antacids, iron, or calcium supplements within 4 hours of taking this medicine.

Take this medicine with a full glass of water.

What if I miss a dose?

Do not miss a dose. If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: chest pain, pounding heartbeat, shortness of breath, tremors, leg cramps, confusion, vomiting, diarrhea, seizures.

What should I watch out for?

You will need to have blood tests regularly to see how this medicine affects you. Keep all appointments for these tests.

This medicine should not be used for weight loss. Life-threatening effects could occur.

Do not change brands of this medicine without talking to your healthcare provider or pharmacist. Other brands may affect you differently.

This medicine may cause chest pain when you exercise. Contact your healthcare provider right away if you have chest pain.

If you need emergency care, surgery, or dental work, tell the healthcare provider or dentist you are taking this medicine.

Diabetics: This medicine may affect your blood sugar level and change the amount of insulin or other diabetes medicines you may need. Talk to your healthcare provider about this.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat).

Serious (report these to your healthcare provider right away): Chest pain, trouble breathing, rash, fast or irregular heartbeat.

Other: Diarrhea, weight gain or loss, change in appetite, headache, irritability, heavy sweating, change in menstrual periods, leg cramps, nervousness, trouble sleeping, tremors, vomiting, fever.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• amiodarone (Cordarone)
• antacids or vitamins that contain aluminum, calcium, magnesium, or iron (Take them at least 4 hours before or after you take this medicine.)
• antibiotics such as rifabutin (Mycobutin) and rifampin (Rifadin, Rimactane)
• antihistamines (for example, hay fever products), decongestants such as pseudoephedrine (Sudafed), and diet medicines
• antiseizure medicines such as carbamazepine (Tegretol), phenobarbital, primidone (Mysoline), and phenytoin (Dilantin)
• birth control pills and hormones such as estradiol (Estrace, Estratab), conjugated estrogens (Premarin), norethindrone (Aygestin, Micronor), norgestrel (Ovrette), megestrol (Megace), and medroxyprogesterone (Provera, Curretab, Cycrin)
• medicine that reduces the chance of blood clots forming such as warfarin (Coumadin)
• cholestyramine (Questran) and colestipol (Colestid) (take them 4 to 5 hours apart from this medicine)
• corticosteroids such as cortisone (Cortone), betamethasone (Celestone), dexamethasone, fludrocortisone (Florinef), hydrocortisone (Cortef, Hydrocortone, A-HydroCort), methylprednisolone (Medrol), prednisone (Meticorten), prednisolone (Delta-Cortef), and triamcinolone (Aristocort, Kenacort)
• diabetes medicines such as insulin, glyburide (DiaBeta, Micronase), glipizide (Glucotrol), repaglinide (Prandin), metformin (Glucophage), rosiglitazone (Avandia), pioglitazone (Actos), and tolbutamide (Tol-tab)
• digoxin (Lanoxin)
• epinephrine (Adrenalin)
• herbal remedies such as guarana and ma huang (ephedra)
• iodine (including radiographic contrast media used in CT scans)
• lithium (Lithobid)
• orlistat (Xenical)
• selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft)
• sucralfate (Carafate)
• sulfa medicines such as sulfamethoxazole (Bactrim, Septra) and sulfisoxazole (Gantrisin)
• tamoxifen (Nolvadex)
• theophylline
• tricyclic antidepressants such as amitriptyline, nortriptyline (Aventyl, Pamelor), imipramine (Tofranil), and doxepin (Sinequan)

Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.