People's Pharmacy

Synthroid

Generic Name:levothyroxine

Revised:4/1/2000

Table of Contents

Side Effects and Interactions

Side effects of thyroid replacement therapy are rare if the dose is appropriate.

Specialists recommend beginning treatment with a low dose and gradually increasing it until symptoms of underactive thyroid disappear and the TSH blood test is normal. This may initially require blood tests every four to six weeks and good communication with the doctor.

Signs of overdose include insomnia, heart palpitations, jitteriness, rapid heart beat, increased sweating, higher blood pressure, changes in appetite, and reduced menstrual flow.

Other adverse reactions of excessive thyroid levels include tremor, headache, heart disease, diarrhea, and weight loss.

Report any such symptoms to your physician promptly.

A number of medications may interact with Synthroid or alter the tests that detect thyroid problems.

People taking estrogen, asthma medicines, decongestants (including those found in over-the-counter cold or flu remedies), antidepressants, certain cholesterol lowering drugs, blood thinners such as Coumadin or heart medicine like digoxin should check with a physician or pharmacist.

In theory, the herb guggul might counteract thyroid-suppressing drugs or increase the effect of thyroid hormones. Monitoring thyroid function is prudent.

Licorice may alter the required dose of levothyroxine because of its impact on the thyroid gland.

Never stop taking Synthroid without first checking with your health care provider.