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Generic name: dextrothyroxine (dex troe thye ROCK sin)
Brand name: Choloxin
Drug class: Miscellaneous antihyperlipidemic agents

What is dextrothyroxine?

Dextrothyroxine is used to lower high cholesterol (a type of fat) levels in the blood.

Dextrothyroxine may also be used for purposes other than those listed in this medication guide.

What is the most important information I should know about dextrothyroxine?

Follow any diet or exercise plan outlined by your doctor. Diet and exercise are very important factors in controlling cholesterol.

Call your doctor immediately if you experience chest pain, shortness of breath, an irregular heartbeat, sweating, headache, or a skin rash. These could be early signs of serious side effects.

Who should not take dextrothyroxine?

Do not take dextrothyroxine if you

  • have had a heart attack,

  • have heart disease,

  • have angina,

  • have irregular heartbeats,

  • have rheumatic heart disease,

  • have congestive heart failure,

  • have high blood pressure,

  • have a history of iodism (iodine poisoning),

  • have liver disease, or

  • have kidney disease.

Dextrothyroxine can have serious effects on the heart, and it should not be taken if you have any of the conditions listed above.

Dextrothyroxine is in the FDA pregnancy category B. This means that it is unlikely to harm an unborn baby. Do not take dextrothyroxine without first talking to your doctor if you are pregnant.

It is not known whether dextrothyroxine passes into breast milk. Do not take this medication without first talking to your doctor if you are breast-feeding a baby.

How should I take dextrothyroxine?

Take dextrothyroxine exactly as directed by your doctor. If you do not understand these instructions, ask your pharmacist, nurse, or doctor to explain them to you.

Take each dose with a full glass of water.

Store dextrothyroxine at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take only your next regularly scheduled dose. Do not take a double dose of this medication.

What happens if I overdose?

Seek emergency medical attention or call a poison control center near you.

Symptoms of a dextrothyroxine overdose are unknown.

What should I avoid while taking dextrothyroxine?

Follow any diet or exercise plans outlined by your doctor. Diet and exercise are very important factors in controlling cholesterol.

Dextrothyroxine side effects

If you experience any of the following serious side effects, stop taking dextrothyroxine and seek emergency medical attention:

  • an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

  • chest pain or an irregular heartbeat;

  • sweating;

  • diarrhea;

  • headache; or

  • skin rash.

Other, less serious side effects may be more likely to occur. Continue to take dextrothyroxine and talk to your doctor if you experience

  • insomnia, nervousness or tremor;

  • ringing in your ears; or

  • nausea, vomiting, decreased appetite, or weight loss.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

What other drugs will affect dextrothyroxine?

Dextrothyroxine may increase the effects of the following drugs, which could lead to dangerous side effects:

  • anticoagulants (blood thinners) such as warfarin (Coumadin), which could lead to bleeding (a dose reduction may be necessary);

  • tricyclic antidepressants (TCAs) such as amitriptyline (Elavil), doxepin (Sinequan), and nortriptyline (Pamelor), which could lead to nervousness, a fast heart rate and other side effects;

  • other commonly used TCAs, including amoxapine (Asendin), clomipramine (Anafranil), desipramine (Norpramin), imipramine (Tofranil), protriptyline (Vivactil), and trimipramine (Surmontil); and

  • thyroid replacement hormones (dextrothyroxine is a form of thyroid hormone and may affect thyroid hormone therapy).

Dextrothyroxine may decrease the activity of the following drugs:

  • antidiabetic agents such as insulin, glyburide (Micronase, Diabeta, Glynase), glipizide (Glucotrol), tolbutamide (Orinase), and tolazamide (Tolinase), which could lead to high blood sugar levels;

  • digoxin (Lanoxin, Lanoxicaps) (used to treat heart conditions);

  • beta-blockers (used to treat high blood pressure) such as acebutolol (Sectral), propranolol (Inderal) and metoprolol (Lopressor), which could lead to high blood pressure; and

  • other commonly used beta-blockers, including betaxolol (Kerlone), carteolol (Cartrol), carvedilol (Coreg), labetalol (Normodyne, Trandate), nadolol (Corgard), pindolol (Visken), and timolol (Blocadren).

The cholesterol-lowering effects of dextrothyroxine may be reduced by cholestyramine (Questran), which is another cholesterol-lowering drug. These drugs should not be taken at the same time.

Drugs other than those listed here may also interact with dextrothyroxine. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.

Further information

  • Your pharmacist has more information about dextrothyroxine written for health professionals that you may read.

What does my medication look like?

Dextrothyroxine is available with a prescription under the brand name Choloxin. Other brand or generic formulations may also be available. Ask your pharmacist any questions you have about this medication, especially if it is new to you.

  • Choloxin 2 mg--round, yellow, scored tablets

  • Choloxin 4 mg--round, white, scored tablets

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.