The following drugs may cause medical problems if you use them with levothyroxine:
lithium, amiodarone, or antidepressants. Tell your doctor if you have recently received radiation
therapy with iodine (such as I-131).
This list is not complete and there are many other drugs that can interact
with levothyroxine. Tell your doctor about all the prescription and over-the-counter
medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by
other doctors. Do not start using a new medication without telling your doctor.
Certain medicines can be continued, but they may make levothyroxine less effective if
taken at the same time. If you use any of the following drugs, use them at least 4 hours before or
4 hours after you take levothyroxine:
calcium carbonate (Caltrate, Citracal, Oystercal, and others);
ferrous sulfate iron supplement;
sucralfate (Carafate);
sodium polystyrene sulfonate (Kayexalate, Kionex, and
others);
antacids that contain aluminum (Amphojel, Gaviscon,
Maalox, Mylanta, Riopan, Rulox, Tums, and others); and
cholesterol-lowering drugs cholestyramine (Questran) and
colestipol (Colestid).
Stop using levothyroxine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face,
lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
headache;
sleep problems (insomnia);
nervous or irritable feeling;
fever, hot flashes, sweating;
changes in your menstrual periods;
appetite changes, weight changes;
Less serious side effects may include mild hair loss.
This is not a complete list of side effects and others may occur. Tell your doctor about any
unusual or bothersome side effect.
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