Synthroid's Effect on Eyes

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Synthroid's Effect on Eyes

Question:

Does Synthroid affect the eyes?

Answer:

Synthroid is the brand name for levothyroxine. Of the thyroid replacement medications on the market today, levothyroxine is the one prescribed most commonly. Other brand names are Levoxyl, Levothroid and Unithroid.

The drug itself should not affect the eyes. However, if a person was not taking enough or taking too much, there could be some eye symptoms such as blurry vision.

Doctors routinely order a blood test called thyroid stimulating hormone to determine if the levothyroxine dose is correct. Assuming that the dose of levothyroxine is keeping the hormone in the normal range, then another cause for eye problems should be considered.

However, some thyroid conditions are associated with eye problems. For example, in people with the overactive thyroid condition called Graves' disease, the eye muscles can swell, causing bulging eyes that don't move normally. Some people with an underactive thyroid will have dry eyes, even if the levothyroxine dose corrects the thyroid stimulating hormone level appropriately.

Howard LeWine, M.D., is chief editor of Internet Publishing at Harvard Health Publications. He is recognized as an outstanding clinician and teacher and is a recipient of the Internal Medicine Teacher of the Year award at Brigham and Women's Hospital. Dr. LeWine continues to practice Internal Medicine; most recently he became a hospitalist after practicing primary care for over 20 years.

Last updated:	July 20, 2009