Side Effects of Levthyroxine

Levothyroxine is a synthetic version of the naturally occurring hormone thyroxine, which is produced by the thyroid gland. Available as a generic drug and under name brands like Synthroid and Levoxyl, levothyroxine is primarily prescribed to treat underactive thyroid gland (hypothyroidism). Many side effects are possible.

Function

• Levothyroxine replaces deficient levels of thyroxine, a hormone essential for regulating brain function, metabolism and body temperature.

Prevention/Solution

• Levothyroxine side effects usually result from dosages that are too high, causing effects similar to those of an overactive thyroid gland (hyperthyroidism). Having a health care practitioner adjust the dose should solve most problems.

Side Effects

• Many side effects are caused by an unnecessarily high dosage. These include anxiety, diarrhea, fever, headache, increased appetite, insomnia, nausea, feeling hot and flushing or sweating, tremors and weakness.

More Serious Side Effects

• More serious side effects may include seizures, high blood pressure, heart palpitations and heart attack.

Drug Interactions

• Levothyroxine can cause changes in blood sugar levels, so diabetics may need to adjust dosage of insulin or other medication. Levothyroxine also interacts with anticoagulants, beta blockers, birth-control pills and some cholesterol-lowering drugs.