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Synthroid

Generic name: Levothyroxine (pronounced [LEE-voe-thye ROX-een])

Drug class: thyroid drugs

What is Synthroid?

Synthroid, a thyroid medication, replaces the hormone that is normally produced by the thyroid gland in order to regulate your body's metabolism and energy. Synthroid, a prescription medication, is prescribed to treat hypothyroidism. When your thyroid cannot produce enough levothyroxine, it is prescribed.

Synthroid can also be used by patients who require surgery and radioiodine treatment to treat a well-differentiated type of thyroid carcinoma.

Warnings

If you suffer from certain medical conditions, you may not be allowed to take Synthroid. You should tell your doctor if any of the following conditions exist: an untreated or poorly controlled adrenal gland disorder; a thyroid condition called thyrotoxicosis; or recent or current symptoms that may indicate a heart attack.

Before you take this drug

Levothyroxine can cause dangerous side effects and even death if it is misused, especially when combined with other appetite suppressants for weight loss medications.

Levothyroxine is available to almost everyone, as thyroid hormone is produced naturally by the body. You may not be allowed to take the medicine if certain medical conditions exist.

Tell your doctor about any of the following to ensure that Synthroid will be safe for you:

  • Uncontrolled or untreated adrenal gland disease;
  • A thyroid disorder known as thyrotoxicosis
  • Heart attack symptoms (chest pain, heavy feeling or pain that spreads to the shoulder or jaw, nausea, or general feeling of unwellness).
  • A thyroid nodule
  • Heart problems, such as heart attacks, strokes, blood clots, or disorders of blood clotting;
  • Diabetes: you may need to adjust your diabetes medication;
  • Anemia (low blood red cells)
  • Weak bones (osteoporosis), or low bone mineral density;
  • You may have problems with your pituitary.
  • Allergies to food or drugs
  • Plan to have surgery
  • Recently received radiation treatment with iodine, such as I-131; or
  • Kidney disease is a serious condition.

Do not stop taking Synthroid without consulting your doctor if you become pregnant. Low thyroid hormone levels could be harmful to both mother and child. Your dose requirements during gestation may differ. Inform your doctor that you are breastfeeding. You may need a different dose while nursing. Do not administer this medicine to an infant without consulting a doctor.

How to take Synthroid?

Follow the instructions on your prescription label and read all medication guides or instruction sheets. Carefully follow all instructions and directions included with your prescription. Sometimes your doctor will change the dose. Take Synthroid 30–60 minutes before your breakfast on an empty stomach. Take your medicine according to the instructions of your doctor and at the same time every day.

The Synthroid tablet can be administered to children and infants who are unable to swallow the whole tablet by crushing it and mixing it with a small amount of water (5–10 ml, or 1–2 teaspoonfuls), and then giving the mixture immediately by spoon or dropper. The crushed tablet/water mix should not be stored, and it shouldn't be given with foods that decrease levothyroxine absorption, like soybean-based infant food.

The dose of levothyroxine is based on the weight of the child. If your child loses or gains weight, the dose needed may change. Synthroid may take several weeks to start working. Continue to use this medication, even if it makes you feel better. Synthroid may be needed for the rest of your life.

You may require frequent medical tests. Inform any doctor, surgeon, or dentist who treats you about your use of Synthroid. Store away from heat and moisture at room temperature. This medicine should never be shared with another individual, even if their symptoms are similar.

What happens if I miss the dose?

If you are almost due for your next dose, skip the missed one. Never take two doses of the same medicine at once.

What happens if I overdose?

Call 1-800-222-1222 for poison help or seek immediate medical attention.

Overdose symptoms include headaches, tremors, or leg cramps. They may also be accompanied by feelings of nervousness or irritation, chest pains, shortness of breath, pounding pulses, and a feeling of nervousness or irritability.

What should be avoided?

Avoid these foods that can cause your body to absorb less levothyroxine.

Side effects of Synthroid

If you experience any of the following symptoms of an allergic reaction: hives, difficulty breathing, swelling of your lips, face, tongue, or throat, please seek emergency medical attention.

If you experience:

  • Fast or irregular heartbeats
  • Chest pain is pain that spreads to your jaw, shoulder, or neck.
  • Shortness of breath
  • Heat flashes;
  • If you experience unusually cold temperatures or tremors,
  • Weakness, tiredness, and sleep problems (insomnia);
  • Memory problems; feeling depressed, irritable, or angry
  • Headaches, cramps in the legs, and muscle aches are all symptoms of a headache.
  • Feeling nervous or irritable
  • Hair loss is dryness of the skin or hair.
  • Irregular menstrual periods;
  • Vomiting, diarrhea, appetite changes, and weight changes.

Some side effects are more common in older adults.

Synthroid side effects include:

  • Chest pain and irregular heartbeats
  • Shortness of breath
  • Headache, cramps in the legs, or muscle pain and weakness
  • Tremors, feeling nervous, irritable, or trouble sleeping
  • Increased appetite
  • Feeling hot
  • Weight loss;
  • Changes in your menstrual cycle;
  • Diarrhea;
  • Skin rash, and partial hair loss.

There may be other side effects. For medical advice on side effects, call your doctor. The FDA can be contacted at 1-800-FDA-1088 to report side effects.

Interaction with other drug

Your thyroid hormone level can affect many other medications. Synthroid can also be affected by other medications.

Levothyroxine can be less effective when taken with certain medicines. Avoid taking any of these drugs within 4 hours prior to or after Synthroid.

  • Calcium Carbonate
  • Cholestyramine, colesevelam, and colestipol;
  • Ferrous sulfate iron supplement;
  • Sucralfate;
  • Sodium polystyrene sulfonate (Kalexate, Kayexalate, Kionex);
  • Stomach acid reducers: Esomeprazole (lansoprazole), omeprazole (rabeprazole), Nexium, Prilosec (prevacid), Protonix (Zegerid), and others can help lower stomach acid.
  • Antacids that Contain Aluminum or Magnesium: Gaviscon, Maalox Milk of Magnesia, Mintox Mylanta Complete Pepcid, and other brands

Levothyroxine can interact with many drugs. These include prescription and over-the-counter medicines, vitamins, and herbal products. This list does not include all possible interactions. Inform your doctor of all medications you are currently taking and those that you will stop or start using.