Be Wary of Drug Combinations
Foods and supplements aren't the only substances that can impact the way your thyroid hormone replacement works. Certain drugs can impact the effectiveness of your thyroid treatment, too. At the same time, thyroid hormone can have an effect on how these drugs work. That's why it's critical that you tell your doctor all the medications you are taking before he puts you on a thyroid drug.
Here is a partial list of the kinds of drugs that can affect your thyroid medication:
Cholesterol-lowering Medications: Drugs that reduce cholesterol levels, such as Colestid and Questran, bind thyroid hormones and make them less effective.
Diabetes Drugs: Diabetics who rely on insulin or sulfonylureas may notice that these treatments are more or less effective when they start taking thyroid medications.
Antidepressants: When taken with thyroid hormone replacement, the therapeutic and toxic effects of tricyclic antidepressants may be increased. If taken with a selective serotonin reuptake inhibitor (SSRI) such as Prozac or Zoloft, your thyroid medication may become more or less effective.
Anticoagulants: Medications such as warfarin (Coumadin) that are used to prevent blood clotting — known as blood thinners — can sometimes become more potent in the presence of thyroid medications.
Estrogen: Contraceptives and hormone replacement therapy that contain estrogen may decrease the amount of thyroid hormone in your body and require you to take a higher dose.
Anticonvulsants: Taking thyroid hormone replacement with drugs used to treat convulsions, such as Dilantin, can speed up the metabolism of the thyroid medication.
Gastrointestinal Medications: Antacids that contain aluminum or magnesium, sucralfate (Carafate), and simethicone (GasX) can all affect the way your body absorbs thyroid hormone replacement.
Beta-blockers: People who have high blood pressure, heart failure, or previous heart attacks may take drugs called beta-blockers. The potency of certain beta-blockers such as metoprolol(Lopressor) or propranolol (Inderal) may be reduced when you start taking a thyroid drug.
Other drugs that warrant mention include aspirin, steroids, amphetamines, theophylline (for asthma), and medications used to reduce appetite or lose weight. The effectiveness of all these medications may be affected when you start taking thyroid hormone replacement.
Obviously, the list of drugs that interact with thyroid medications is a lengthy one. Again, that's why it's critical that you tell your doctor about
Life changes and disruptions in your habits and routines can also affect how well your thyroid medication works, even after you've figured out your dosage and been on it for a while. Bouts of stress, starting a high-fiber diet, or going on birth control pills, for instance, can all increase your need for more thyroid medication.
If you notice that your medication no longer seems to be working and your symptoms of hypothyroidism have returned, talk to your doctor. By doing some detective work, she may be able to pinpoint the reasons why your medication has become less effective. She'll also be able to adjust your dose to a level that does work.
If you'd like a listing of drugs that can affect your thyroid medication, check on the Internet for the individual medications. Many, such as Synthroid (